Idle adjustment question

[abracadabra]

Folks-

My van is idling a touch low, its usually 600-650 when warm. Its been like this for a long long time but I'm now getting around to looking at the specs, and see that for my '87 LE with Auto it should be 750.

I've got the FSM and it tells me all the stuff to do, its very straightforward. But I have one question: it says to remove the "ISC VSV" connector. Why do you need to do this? Why can't you just adjust the screw with a warm engine in neutral to 750?

Its just that I like to know the "why" sometimes, I have no problem disconnecting the connector if need be, not like its hard to do.

thanks!

Mark

[timsrv]

The ISC VSV influences the idle speed at times. They just tell you to disconnect to be sure it won't mess with your adjustment. Don't mess with the throttle body stop screw. As I'm sure you know, there's a little rubber flap on the front side of the throttle body with the idle adjustment screw under it. Adjust idle speed there using a flat tip screw-driver. Tim

[abracadabra]

Thanks, that totally makes sense.

Its funny, I saw the rubber cap where the adjustment screw is, so easy to find and access, and I thought "finally, something on this van that is easy to get to"!!!!
I'm thinking of the air filter (and so many other things) where on any other vehicle it would be so straightforward....but not on these rigs!

Anyway we took a great trip today outside the city and I had the screwdriver up front, figured I'd set the idle while the van was good and warmed up after an hour on the road.

I went by the FSM, they say to set idle in Neutral......the funny thing is, my idle in Neutral (and Park) is right at 750-800 (should be 750). It doesn't say anything about setting the idle in Drive.

I put the van in Drive, it idles at 600-650. I'm giving estimates on the RPM because I didn't hook up my meter, I'm going by the dashboard, its hard to be super precise there.

Its done this forever, its not an issue but I'm confused a little: should the idle be 750 in neutral AND Drive? Or is my idle in Drive not a problem?

thanks!

Mark

[timsrv]

It's completely normal for RPMs to drop to about 600 or so while in gear (automatics).

[filterway]

I have the same kind of question. I changed 2 weeks ago the TPS on my van. Now my idle speed at "D" position (waiting at a taffic light for exemaple) is 650, but in neutral position it's 1200.

My question is: how to adjust the idle speed? The manual show special tool to do it. Is it simply turn the idle screw under the rubber cap on the throttle body?

my second question is: if i adjust idle speed at neutral position, does it will affect idle speed at "D" position? )

Jerome

[timsrv]

You set it with the engine in park or neutral & AC off. Whatever RPM you see when in gear is not a big concern (unless it's stumbling or stalling). If it does that, then there's something else going on.........but no sense crossing that bridge until you come to it. Set the idle and see what happens. Tim

[Wrench]

You set it with the engine in park or neutral & AC off. Whatever RPM you see when in gear is not a big concern (unless it's stumbling or stalling). If it does that, then there's something else going on.........but no sense crossing that bridge until you come to it. Set the idle and see what happens. Tim
I'm a little confused tim, awhile ago I adjusted the idle per my service manual and I swear I read 1250 for park and 750 for drive???? Am i way too high? Was thinking it'd be nice to have it lower to avoid lurchy shifts.

[Wrench]

I'm a little confused tim, awhile ago I adjusted the idle per my service manual and I swear I read 1250 for park and 750 for drive???? Am i way too high? Was thinking it'd be nice to have it lower to avoid lurchy shifts.
Is this poster wrong? I think I might have seen this and been misinformed
9190

[timsrv]

I can't read that (too small). Idle speed is set in neutral or park. The service manual calls out 700 rpm for manual transmission and 750 for automatic. It's not a super critical thing to have it right on. I would not want "hot" idle speed to be more than 900 rpm's on an automatic as this builds heat in your transmission when sitting for long periods at a light (foot on the brake while in gear). It also puts unnecessary forces on the drive train when putting it into gear from park or neutral. Tim

[Wrench]

I can't read that (too small). Idle speed is set in neutral or park. The service manual calls out 700 rpm for manual transmission and 750 for automatic. It's not a super critical thing to have it right on. I would not want "hot" idle speed to be more than 900 rpm's on an automatic as this builds heat in your transmission when sitting for long periods at a light (foot on the brake while in gear). It also puts unnecessary forces on the drive train when putting it into gear from park or neutral. Tim
Yeah rough shifts are exactly what I'm trying to avoid so I lowered it and it has indeed helped! Thanks for the clarification.

[originalkwyjibo]

Is this poster wrong? I think I might have seen this and been misinformed
9190

I just posted a reply to that thread to correct the misinformation.

[timsrv]

Thanks Original. As old as it was I was previously unaware of that post. I just searched and found that thread too. To avoid future confusion I put your edit right in that post so readers won't miss it. Since that made your post redundant I deleted it.

[MyToy]

Been working this idle issue for some time now. The main problem is that it changes when driving.
I can set my idle for 800 RPM in park after she is up to temp, say about 15 minutes. Then I drive her for 20 to 30 minutes and when I put her in Park the idle goes up to 1300. If I shut her off and put her back on she stays at 1300. If I shut her off for 15 minutes she starts but shakes, missing at times (Heat Soak Issue). Run till past the heat soak problem and she is back at 1300. So I brought the idle down to 900 only now for the first 15 minutes of run when she is cold she idle so low she stalls.I have to feather the accelerator to keep her going. The Cold start air bypass works and raises the RPM but only for about 30 seconds and then slowing comes down to what should be idle. But she stalls since I turned the idle down when hot at 1300.

Engine runs great, with great gas milage, better than 23mpg.

What would cause the idle to increase so much over time? She is running very cool and is very well regulated by watching the temp gauge.
I thought I would go get some freeze spay and shoot it at some components after she goes high on the idle just to see if I can at least localize it.

Any thoughts?

[timsrv]

Unfortunately (or perhaps fortunately for me) I haven't experienced that problem, so I don't have any gut feelings. When I run into problems that stump me I resort to swapping parts to see what happens. I know you've already changed a bunch of stuff. If there are other things you have still not swapped, I would suggest doing so. Sorry, but without hands-on, that's the best advice I can give. Tim

[Ace MM]

Why do you need to do this? Why
Its just that I like to know the "why" sometimes, I have no problem disconnecting the connector if need be, not like its hard to do.
Vacuum sucks, that's why.
Check those hoses for cracks. Makes you crazy looking for the one:wall: but so satisfying when a new rubber hose fixes it.

[MyToy]

Again, thanks for the feedback.

All rubber hoses been replaced. I did find a crack in my EGR tube that mounts below on the exhaust manifold and I thought that was it. But I still cannot figure this on out. I do believe it is a vac problem still. Today I am going to pick up some starter fluid (Ether) and shoot those vac junctions. I may find one that is leaking still. There are tons of them, who knows. I will stay away from anything that can ignite this stuff.

If it is a thermal issues it has to be located somewhere on top, like the mixture control assembly or any of the sensors not senders. Anything that has a variable input to the MCU may can also be a culprit. I will also pick up some freeze spay and shoot all the parts after it is up at high idle speed. I know it does not change even if I have the engine cover open for some time. It never goes down until she is really cold like less than 100 deg or so.

If all else fails I will mount on the engine a bunch of temp probs to see if anything in particular looks funny at different operation temps.

Will keep you posted.

MT

[Burntboot]

MT - You can use ether and it works just fine but I find it harder to control as it usually under significant pressure, tends to spray all over.
These days I use a propane torch, easy to control the flow and I find its better for pin-pointing leaks.

I also choose to believe its a little safer, mostly because I can control the amount I use as opposed to a blast here and a blast there.
I once had an exhaust leak ignite ether, it was quite the experience and why I now use propane - YMMV

BB

[timsrv]

Many things will work. I've even used carb cleaner and WD-40 (although I don't recommend WD-40 due to the residue mess). I've also had ether accidentally ignite and although scary, it was just a flash fire and was gone almost as soon as it started. It did however burn long enough to take some arm hair :yikes:. Tim

[MyToy]

OK, I will watch myself. I have a small portable propane for fixing plumbing stuff. So I can just turn on the gas and point it to the areas I want to test and it will race if it is leaking like the ether?
Cool, I will give it a go.

MT

[MyToy]

A bit of an update on this.
I tried the propane, hey look at me? I am still alive and kicking!

Anyway it did not show anything.
Since it runs so rough under 800 rpm no matter what temp she is resting at I decided to pull the plugs and take a look at the way they are burning.
As you can see by the pic they are all the same and they are seem to be very light tan.
Could this be that they are burning to lean?
Then through in the temp senders job. For sure its resistance reporting to the MCU must control its mixture, low resistance lean and high resistance rich. Just a guess.

So I tried just yanking the temp connector off while it was running, hot at this point, high idle rpm.

Did nothing except forced my check engine light to come on.

Checked the sender and when hot it is at 408 ohms and cold it is 20,0000

So the temp sender is working and not doubt linear also.
So my next question is if the MCU is the problem?
To do this I will pull the MCU and check for continuity to the temp sender and make sure there is no issue there.
If OK, which it most likely will be, I will build an outside potentiometer that can slide between 20K and 200 ohms. In theory I should be able to set that for 20K, start the engine and slide it down to 200 ohms and she should do something, like stall from being too lean. If I get no response at all then the MCU is the problem.

Any comments?

[MyToy]

Correction on my last thread. The high resistance on the Temp sender was 2000 ohms and the low was 408.

Also, when I went to move her out to the drive way my power steering pumps went down making all kinds of rattling noises and got much worse when I turned the wheel.
So now I have to contend with yet a third pump in less than a year.
Anybody know a pump that lasts!!!!:wall:

[timsrv]

Your plugs look good. A light tan is what you want with these fuel injected engines (carbs burn more earthy brown). Personally, since the van is almost 40 years old, I think it's a good idea to have an extra ECU laying around. I think you should have at least one extra of every critical part. They make great troubleshooting tools and you never know when you might have a failure. I got most of my spare parts ~ 15 years ago when you could easily find them for ~$20 on eBay, but things are drying up and becoming more expensive now. This situation will probably continue getting worse, so if you don't already have spares, grab them now.

I had a rough running issue about 7 years ago and it took a while before I got around to swapping ECU's. By golly that was it, and it was my 1st ECU failure ever. I had a hard time wrapping my mind around it so I swapped it back.........and the problem came back. I threw the bad one away because I never wanted to accidentally install it again. These early Toyota ECU's are built tough, but 35+ years of humidity and extreme temps will take their toll on anything. I'm not saying yours is bad, but it's certainly a possibility. Tim

https://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=1986+toyota+van+ecu&_sacat=0

[MyToy]

Wow, and I thought I was an early bird.,
Yeah OK. Thanks for the link. I will see what part number I have and get one.

Thanks for the advice.

Will keep you posted

MT

[MyToy]

I ordered a ECU today. Ebay had several with my identical numbers on the case.
Now I only have to pray it works.
Should have before the weekend.

MT

[timsrv]

We just got a contribution in the form of a PDF file from member "PrecisionDriven" for those who may need help replacing their ECU. Here's a link:

https://www.toyotavantech.com/forum/content.php?257-How-to-replace-your-ECU

[MyToy]

Hey this is great.

Although I have already done this, it is a great reference to have. Great Job Steve!

MT

[MyToy]

A little up date on my engine with the shakes and idle issues.
Replaced the ECU, no change.

Something deeper here. For the idle to increase 800 RPM from just when the cold bypass air valve opens to 15 minutes of run time. My next experiment is to remove the temp senser plug from the senser and build a 20K potentiometer to put in its place. I will manual follow the temp/resistance curve in the SM to see if this can be the issues.

MT

[Burntboot]

MT - seeing as you've now ruled out all the likely suspects I feel the need to grasp at straws. :)

Long shot here but, is there any chance the throttle cables are mal-adjusted (throttle and/or trans kick-down)
I have seen (not on a TV) where an overly tight cable would shorten as it heated up causing a higher idle that drove everyone nuts.
I have also seen an excessively filthy throttle plate cause hot/cold idle issues
I doubt either of these things are your problem, but sometimes it's the most basic things that are so easy to overlook.

I am a little embarrassed at the number of times I have chased a ghost for hours only to find I made a stupid mistake.
Its always the little things, like the bolt you forgot to tighten cause its hidden from view, or the gasket that got folded as you weaselled a part into a tight spot, or the connector not plugged or the hose clamp that's installed on a slight angle so that its tight, but really isn't.

[MyToy]

Burnboot:

Great idea!!!

It is very tight when cold, I made it perfect, which may be changing with heat. I will check that out.

Again, great point!!!

MT

[timsrv]

I am a little embarrassed at the number of times I have chased a ghost for hours only to find I made a stupid mistake.
Its always the little things, like the bolt you forgot to tighten cause its hidden from view, or the gasket that got folded as you weaselled a part into a tight spot, or the connector not plugged or the hose clamp that's installed on a slight angle so that its tight, but really isn't.

Amen to that.......This is something every true mechanic can attest to :yes: :wall:.

[MyToy]

Up date on this idle issue.

Replaced the computer and no change, but at least I have one just in case.
Found the temp sensor to be out of spec according to the temp/resistance curve in SM. So I replaced that. Did another curve on the new one and it was better but not perfect. It did improve idle a bit but not much.
Tried and tested the accelerator cable if maybe it was lighting up with heat, no issue there.

With a bit more studying I discovered that the temp sensor is in series with the dividing network in the Air Flow system. So it does seem that the mixture, or at least the adjustment for this system can be partly done externally by changing the resistance with the Temp sensor. The question is what does the temp sensor really do in our vans? Let's find out.

I removed the sensor connector from the sensor and replaced it with a 2000 ohm potentiometer. I picked this value since the sensor I just got was 1800 ohms at room temp, 75deg and when hot it was down to about 300 ohms.

So I installed it in the system with a stone cold engine. Adjusted it for 1800 ohms and gave it a whirl. Started right up as norm, raced at 1300 rpm during cold start air bypass valve then, like clock work, slowly lowered to about 500 and the shakes. Water temp is still pretty cool, no registration on the temp meter yet, so I decrease the pot to about 1000. No change, 500 ohms, no change, in fact no matter where I set it there was no change, no nothing. You would never know it was even there. However if you increased the resistance above 1800 RPM the check engine light came on. So it is talking to the MCU, that we know. So why is there no other change? No change in idle, shakes, exhaust gas, nothing. This leads me to the air flow controller. It is nothing but a dividing network with one leg that goes to the temp sensor and then to the MCU and another an air temp sensor inside the unit and it has a separate port for the MCU. Today I will attempt to do some DC measurements on this device and see if just maybe a resistor is open or changed in value. What I would like to do is move the flow meter's sail manually and see if has any effect on the shakes.
Then again, after driving for 15 minutes her idle claims to 1000 in drive and 1400 in park. Needless to say she does not shake here.

So the way it stands there are three idle conditions that one has to deal with.
1 30 seconds after the cold start air bypass starts, drops to 500 and shakes
2 Drive for 5 minutes increases to 600 and shakes, van jumps forward with each shake. Not pretty in heavy parking lot with pedestrians.:no:
3 15 min of drive time no shakes, idle in drive 1000RPM and Park 1400rpm.
4 Stop for 10 minutes and no start. 5 to 10 retries to get it up and pumping pedal, must be heat soak here.

Needless to say, when she is idling at 1400 in park it is not a pretty sight putting her in gear. Ouch!!!!

MT

[MyToy]

Update on Flow meter:

I built several different divider designs with little to no effect.:no:

So I pulled up my pants and decide to dissect the flow meter which I did not want to do but......


Well the top came off real easy. Just a screwdriver around the parameter and wedged it up.

So there it was, this mechanism that was a mystery to me. But not any more.

It isn't really as the SM describes it. The resistors are at board level and are part of the traces themselves. Little you can do electrically. So I started her up and watched as it did its thing.

As many of you know this device also turns on the fuel pump. There is a small leaf switch that disconnects the pump from power until there is a tiny bit of suction by way of the air filter at start up. With that the door inside the meter opens and allows the switch to close. So there will always be some kind of delay for start due to this start up sequence.

Waited around for it to start to shake and manual turned the pot which of course is connected to the door. RPM goes up to a point, then falls. So I reduced my idle to compensate for the increased idle speed. Now, without any help from the throttle this baby will never run.

However, once I grabbed hold of the pot and moved it counter clockwise the idle restored to about 900 with no shakes. This is inconclusive due to the multiple issues I have but it was at least a start. I did do all the resistive tests and all were OK. I can only think that the 10% ethanol fuel I am using may be causing this. Not sure. It does seem to be adjustable but only mechanically and from the viewpoint in the van you cannot see it all. Nor would anyone would be able to do this fine detailed work. The unit has to be removed and put on a bench.

So I started looking around to see if I can find one to use as a test sample to open and determine how to correct this mixture internal to the unit.

Looked on Ebay and they are big bucks for something I would probable never use. So big educational curve here.

If anyone has or knows where to get one please chime in . It does not have to work. But this cadaver could be the answer for at least a smoother running engine. The high idle issues I am having I can deal with but getting rid of the shakes would be formost.

I found a gas station way out in the sticks that sells non ethanol fuel. It is for the landscape guys and their lawn mowers and stuff. So I am down to a little less than a quarter of the tank so I am going to drive out there this morning on the way to work and top it off with non ethanol to see if that has any effect on this.

Again, will keep all posted.

MT

[Burntboot]

MT - I hope your change to ethanol solves your issues but I am a little doubtful.

All the cars i have seen that had issues due to ethanol required parts replaced prior to running again, and every single one came in on the hook.
My ancient little outboards hate the stuff as it easts their O-rings and fuel lines and if it sits it around for any amount of time (like during the off season) it turns into a gell and clogs everything. Nasty stuff it is.

All my vehicles seem to run better on real gas but the differences are not "dramatic"

IIRC correctly, a long time ago you had some issues with tank rust and clogged injectors, have you rechecked fuel pressure and watched them while it's acting up?

[MyToy]

Right again! It does not seem the fuel made any difference except for the price, a dollar more than reg.

I have not checked pressure since the top end overhaul. I did in fact install the super filter Tim used and I have been watching that every 500 to 1000 miles. It still catch some rust but I think it stops there. Remember I also installed another new Toyota fuel filter also that is after the super filter. So running two filters.

Checking the pressure isn't so bad but to check the injectors, as you know, is a huge job. Since the plugs burn so good I believe they are OK. Plus it runs fantastic after she is warm and over 900 rpm.

Due to the increase in RPM when I manually opened the flow door adds more variables due to the decreased idle adjustments I had to make. Now that it seems like the fuel is not going to help out, I am back to the flow meter. The SM also talks about a temp sensor in the EGR somewhere but my van does not have that.

After I got the fuel my check engine light came on. Just what I needed. So tonight I will read those codes and see what happened there.

Just too many variables.

But I will tell you one thing Burnboot, this idle problem has been with me some since I got the van before I did the engine over and the second head replacement. I thought I would also run a compression test on the cylinders just to see what that looks like. Unlikely I will see much but at least I can re-establish a base line there.

Timing is a joke due to the shakes. However, I can at least get it smooth with the air flow control and idle adjustment to try the timing light again.

Still a long way to solving this one. I am sure others have the same issue.

Will keep you posted.

We are going to find this one and share with all.

Later
MT

[VanCo]

As you may know the Vane Air Flow Meter (AFM) uses an air temperature sensor and potentiometer controlled by a vane that moves in relation to the engine's air demand.The Electronic Control Unit (ECU) uses this information (and information from the coolant temperature sensor, and when warm the oxygen sensor) to reference the correct air density and injector duty cycle in a table in its archaic software. Some my say, oh don't forget the Throttle Position Sensor TPS, and on most fuel injected engines they would be right to say that it plays a part in fuel delivery;however, the TPS on this system just tells the ECU when the throttle is closed to allow the computer to perform a fuel cut when decelerating, and when to allow timing changes.

To make the engine start and run the ECU has (very little) control over several outputs. Think original Nintendo level of programming. All of the outputs are controlled referencing pre-programmed tables in the original software. There is no "learning" with these computers like newer ones. The ECU controls the injector pulse width (how much fuel is injected per cycle), ignition timing can be changed, the cold start injector, Air Valve (AV), and some Vacuum Switching Valves (VSV).

The AFM is the single most important input to the ECU. You can unplug all the other sensors and the engine will still run, but not if you unplug the AFM. The only way you should adjust the potentiometer, spring settings, or idle adjustment is if you have a gas analyzer, or a wideband O2 sensor installed. The AFM is amazing, I was able to install an aftermarket turbo and 100cc larger (300cc total) injectors on the stock computer all by adjusting the AFM. I did have wideband O2 as well.

By messing with the AFM you can make it run so lean it will barely run (die), burn valves, and meltdown. You can make it so rich you'll foul plugs and gas yourself out. That is why you need to know what the air fuel ratios are when you are adjusting it. If you adjust the idle using the AFM until it the RPMs are correct, you could be leaning out the entire curve. This could very well toast the engine. Even the idle screw on the AFM will change the entire air fuel curve by a couple of points.

This computer also uses open and closed loop fuel control. Open loop the computer uses no feedback from the oxygen sensor to adjust the injector pulse widths. It does this most commonly on start up, until the oxygen sensor is hot, and the engine is at least 125F, or if there is a problem with a sensor. When an engine is in open loop it is designed to provide a richer air fuel as a safety feature.

In closed loop the computer uses the input of the narrow band oxygen sensor to make adjustments to the pulse width. It does this by reporting to the computer the current rich/lean reading. These are narrow band so they do not give a detailed indication as to what the air fuel is. If the computer gets a signal of lean, it dumps more fuel, it then gets rich,and leans a bit. This happens thousands of times and minute, and the average is close to the proper 14.7 stoichiometric ratio for gasoline.

This allows for better MPG and runnability. The closed loop system on this computer has a maximum of 5% adjustment rich, and 5% lean. If fuel pressure is off it can't adjust to compensate, also if you adjust the AFM incorrectly the computer will not be able to compensate to the appropriate air fuel ratio. This can cause engine damage, poor, MPG, and poor runnability.

If it were me, I would get a wideband O2 gauge. Infact, it's the first "upgrade" all of my cars get. You can instantly know, at anytime, if your engine is running as perfect as can be. You would then be able to tell if your AFM is properly adjusted.

As far as a guess to what your problem is. Have you tried disconnecting all your vacuum lines and plugging the ports? You can do it one by one. Just to eliminate a bad VSV or something like that. Some VSVs are normally open, some normally closed, what if the wrong valve is in there? So the computer tries to idle down, but the wrong VSV is hooked up so it idles up? Just a guess.

[timsrv]

Very nice and thorough response VanCo! You are a valuable member/asset here......Thank you!

I would also like to add the air sensing fuel pump switch in the AFM will not close during cranking (not enough air flow). The ignition switch and the "Circuit Opening Relay" bypass this feature when cranking. By the time the ignition switch returns to "Run", the fuel pump switch in the AFM takes over. Tim

[VanCo]

Very nice and thorough response VanCo! You are a valuable member/asset here......Thank you!

I would also like to add the air sensing fuel pump switch in the AFM will not close during cranking (not enough air flow). The ignition switch and the "Circuit Opening Relay" bypass this feature when cranking. By the time the ignition switch returns to "Run", the fuel pump switch in the AFM takes over. Tim

Thanks Tim!

I spent a lot of time reverse engineering this EFI system to make it work with a turbo. Between a rising rate regulator, tweaking the AFM, and a pressure switch that cut the oxygen sensor only in boost to put it in open loop, I got it as perfect as could be. Now I run aftermarket injection where the sky's the limit.

[MyToy]

Thanks VanCo and Tim:

After replacing the ECU I took a peak inside and it looks like this is using some older TTL chip sets so explains for somewhat archaic software for sure.

Well that is the first time I have had any solid feedback on the operation of this ECU. Great job and thanks.

Ironically after I went and top the tank with non ethanol fuel I got more check engine light notifications.
Reading it back was Temp sensor and O2 sensor.
I cannot really say either of these have to do with my issue since it was doing this long before these went bad. I did replace the Temp sensor last week, so I either have a bad one or the connector is bad. I replaced the connect also about a year ago.

The CO2 sensor was replaced about 18 months ago, again it only started showing up on the check engine just recently long after this idle issue.

So the first thing to do is solve these first. I will order in new ones today and will have before weeks end.

So tell me about this wide band O2 gauge. I checked a few out on the web and it looks like they come with their own O2 sender. So is this something that gets permanently installed in the van? Where does the sensor go? Do you have to drill a hole in the exhaust pipe and install this? This is something I would do right away for sure.

As for the VSV and vac hoses. This was an issue when I got the van back from the bozos that did the fuel injection work. After 10 weeks I removed the van from their lot and nursed it all the way home only to find that much of the vac hoses were wrong. I went by the hose schematic that the boys put up on TVT. I could only find 3 types of VSV, one for the AC which is very different than the rest have an extra port on it. It does make a difference if these are reversed. This has also been replaced. The other two look the same, one under the + batt on the driver side frame and one on the passenger side for the idle up (heat Soak) issue. I tried these manually to see if they work and all were OK. And then there is the one in the EGR circuit, again has been replaced. All of these hoses have replaced.

But I will go through it again as well including the hoses. So if I pull them off one at a time I should just cork the ports with my fingers and if it goes back to normal then it is OK?

The last question is how does the AFM get adjusted? When looking at it I did not see any obvious place to do that. No matter, if I put in the wide band O2 I would want to tweak the system to its best operating condition.

Great input VanCo and thank you so much for taking the time to help out.

Looking forward getting this done for sure.

MT

[VanCo]

I would get it up to temperature and wait for it to go in to its high 1300 rpm idle. Once there, use pliers to pinch vacuum lines that would affect the idle (VSV, etc). There is an idle up diaphragm on the back of the plenum with a larger hose attached, pinch that larger hose too. If the idle drops significantly you can inspect that vacuum circuit specifically. If the hoses are fragile you can pull them and plug them instead of pinching.

The wideband uses a 6 wire O2 sensor. To install it you need to drill a hole in the exhaust and weld in a bung. Muffler shops can do this pretty inexpensively. Most kits come with the weldable bung. They also sell plugs so you can remove the O2 sensor if you wanted.

There is a large cog with a wire retainer in the AFM. Spinning that cog in either direction changes the preload on the vane. Making the vane open easier richens the mixture, making it more difficult leans the mixture. The needle for the potentiometer is slightly adjustable. There is also a aluminum capped screw. It makes changes at idle by allowing air to bypass the vane.

When the ECU gets a signal from the AFM that the vane has been at or near wide open for 3 or so seconds the ECU goes into open loop and runs rich. This is to protect the engine from running too lean at high load and burning valves etc. It doesn't take much for these van to need to run at 95% throttle just to stay out of people's way on the freeway. Since the ECU runs rich in these conditions fuel mileage can suffer. You can also use the wideband O2 sensor to make sure you stay under that threshold in closed loop.

[VanCo]

This site has a great write up on the AFM:

https://www.4crawler.com/4x4/CheapTricks/AFM/index.shtml

[MyToy]

Been getting up to speed on all this, fascinating!

Some good YouTube on the AFM subject as well. Thanks for the link

As for the AFM and its adjustment. I noticed the cog gear when I had it open. It looks like there is a spring with two legs spread eagle that spans the cog holding it down. Is there not some locking mechanism that holds the cog in place when adjusted? If so, then I would have to unlock it to move the cog.

Again, it was hard to see from that angle.

I will check the hoses on the way in today after she starts racing.

I know where all the VSV's are:
One for AC
One for EGR (the one that people always break)
One for super high temp to prevent vapor lock
One that I have no clue what it does. It does work but for what reason I have no clue.

All of these are new within the last year with new hoses so it will be easy to do this test.

The only one with big hoses is the cold start bypass air valve that has a long tube and diaphragm and it is mounted under the intake manifold. Again, these all have new hoses so no problem doing the test.

Thanks for more of this great info VanCo.

Will keep it updated.

MT

[VanCo]

Sure thing!

The large hose I was referring to is the one connected to the AC idle up diaphragm. You can actually pinch the line coming from the intake boot that feeds the diaphragm. That way you can eliminate the power steering pressure valve too. Another thing you can do is short the diagnostic connector (used for checking codes) while it's doing the high idle thing. When in diagnostic mode the ECU can only activate one VSV, the one that bumps RPM up by 100 (by the air box). All other VSVs are deactivated. If you go into diagnostic mode and the idle falls you know you have a vacuum routing/switching problem. If you can't get the idle to fall by pinching lines, or going into diagnostic mode, you may have a vacuum leak to atmosphere.

In my opinion (if no leaks to atmosphere and the cold start valve isn't malfunctioning) the AC idle up diaphragm, and power steering pressure switch are the only things that can cause a single internal "leak" large enough to raise the RPM a few hundred revs.

In the AFM the retainer is all that locks it down. To adjust it you pry one side of the retainer out, and with a flat screwdriver pry the gear to spin it. Then push the retainer back down. Some people remove the retainer with the screw, but that has the potential to cause chaos, especially if nothing is marked.

[MyToy]

Very good, I got the plan. I will solve the fast idle first, then hit the AFM.

Great input. Man it is great to know everything you are saying about all the VSV's. I know all of them by heart!:dance2:

Will let you know. I am sure this will do it.

MT

[MyToy]

And the Saga continues:

Made some progress

Replaced temp sender and O2 sensor. Clear ECU and all is well with no check engine any more.

Started the van from cold, raced at 1200 then went a tad higher when the fan clutch engaged and slowly went down to 1100. All OK there.

Now things begin to go south.

Idle drops quickly to 600. then down to 400 shaking badly. Got in, popped it into drive before she dies and drove to work. I get to work and while in drive it is at 1000 and in park it went to 1500 and stayed there.

Pinched all the are hoses as per your input. This made no difference with the RPM at all.

Then I jumped the check engine connector and the RPM's dropped about 100 RPM. Maybe less than that. It was very little, so small it was hard to see on the vans tach.

So I wonder if I am looking at this backwards. Maybe I should have set the idle when it is at its highest point at 20 minutes. Only problem there is the 500 RPM differential. If it drops 500 from there the engine will most likely die. Not sure but I could try that.

This is working it the other way putting most of my efforts getting the idle up rather than trying to take it down. This may be a waste of time, not sure.

So at the end of the day she is still racing.

I am not sure what is left that would cause it to rise to 1500, have a 500 RPM change from drive to park after 20 minutes of drive time.

It only takes 5 minutes or so for it to level off to operating temp on its internal temp gauge.

I am thinking it has to temperature related but not necessary with the water temp but the ambient temp in the engine compartment. I did leave it running with the seat up and open and after about 5 minutes she was down to 1100.

Now matter what way I cut it she still shakes when below 600 or 700 rpm no matter what.

Any other thoughts? What else can raise the idle?

I am still on the non ethanol fuel.

MT

[timsrv]

I feel your pain MT, and you certainly have more patience than I do. As much as I appreciate your desire analyze and find the exact cause, when it comes to my life, I personally simply don't have time or the patience for that approach. When I get to a certain point, I will usually resort the the "part changing mentality". I know it's cheating and not the proper way, but considering all the parts I have available and the time saving aspect it's a "no brainer". I also justify it by telling myself it's an antique vehicle with diminishing availability for parts, so I make sure to always have at least one known good extra part for everything stashed away. If you have room, and can find a parts van, that can make your life much easier.

If I were having your issue, and I'd already exhausted the easy to check/verify issues, I'd start swapping out parts. You've done the Air Valve and the ECU, so that leaves the AFM, igniter, and distributor w/coil. I'm guessing your problem will be remedied in swapping one of those parts, but if it's not, at least you can rule these things out and move your attention to other areas. If/when you have an eventual failure, you'll already have the spare parts and you'll not be forced to search and pay top price due to an emergency "van-down" situation.

Of course I don't know your situation, so my way may not be right for you. If tinkering is something you enjoy and you have an extra vehicle, + the time/patience, then your current approach could be the right way or even the best way for you. You are certainly obtaining a more intricate knowledge of the inner workings of these components, so if education is your goal, then this is also a good way to learn. Tim

[MyToy]

Appreciate your words of wisdom Tim.

My passion in getting it right is brought on by one thing.

Sure, I could go out and buy any vehicle I please. This is not the issue.
It was time to replace my vehicle and as much as I looked around I found nothing that made me happy.
That is when the wife steps in. Finally after checking out all the crap out there, mostly SUV stuff, she finally put her foot down and said what would make you happy.

That was easy, I wanted MyToy back!! I owned 2 of them back in the day and had to let the last one go since it was part of the company I sold.

But they canned the model and that was it.

So I decided to search for one I could bring back and found this in Seattle
Single owner and new his stuff. He took uber care of her and she sat for 25 years.

What many of you may not have what I have and that is AGE!!!

I had 2 new vans in my life and they were the best thing since sliced bread. I know what they are and I know what they can do. I don't expect it to be new again, but I do expect it to be somewhat what I had. Even with all the stuff I have done on her and left to be done, I love driving her. It's great and besides this idle problem there are others primarily due to the idiots I had do the work on her. I basically had too repaired all they screwed up one at a time on my own and this group of people.

Then you have to consider the group i.e. TVT. It is a great bunch of people that own these beauties and they will all at some point in time have the same issues all of us have had.

I think I mentioned that I am also a pilot and own a vintage airplane. Much older than the van, a true classic. We have 230 in the fleet left with over 200 that went down. So all of us are trying to keep the fleet alive, and alive it is. There are no parts except if you can find one in salvage and that is 100 times rarer than our vans.
The beauty about pilots and airplane enthusiast is they all have their talents from machine work to airframe fabrication. So everyone helps each other out and we pretty much have re-created the factory for the aircraft. And flying her is just as great as driving MyToy.

I have a 1974 Porsche 911. Bought it new and today it is still in mint condition and always can be fix.

Here are some pics of these.

My point is I know that MyToy can come back and I aim to get there without spending stupid money. Did it with the plane and did it with the 911.

Show them the way and they will come.

[timsrv]

I thought the Jodel F-11's were all tail draggers. That's a nice set-up! Van and Porsche are beautiful too! Keep at it and you'll get it figured out. I have no doubt :thmbup:. Tim

Oops, I see it's a Rockwell Commander, never mind

[MyToy]

The plane was actually built by Gulf Stream and was called an Aro-Commander. Rockwell designed her and name her an AC-11.
She has been modified a bit with the 3 Bladed Scimitar Prop and an after market turbo. She will cruise at about 160 MPH at 12,000 feet. The world becomes a smaller place when you have a plane.

Last nights ride home from the office the RPM's went to 1800 in park at idle. It has to be something drastic.

Mt

[MyToy]

One more thing, I believe even if I were to bring the high idle down to some reasonable number the idlescrew would bottom out by then. I will check that this morning when I get to the office.

VanCo was right though. The only thing in the system big enough to make that much of an idle change is either the AC or the cold start Air Bypass, but the pinch test proved those are OK.

What I have not considered was the Mass Flow unit. I am wondering if I could manually reduce the idle by manually turning the wiper in there. It clearly is not a fix but it may give me a hint if it were the mass air flow unit. I can pick up a re-manufactured one from Carid. The show they have one but would rather have a better feeling it could be the culprit. May have to buy it and hope.

I can't see the igniter or the distributor being high on the suspect list for this idle issue.
I also thought it could be something on the air mixture control allowing air to be sucked in from atmosphere when it or a portion of it gets warm. That would be easy, I could just freeze the SOB with a couple of freeze spay cans. It would take a lot but maybe worth it.

Will keep you posted.

MT

[VanCo]

The RPM drop going from 1500 RPM to drive will be different than going from 1000 RPM to drive, due to the load on the torque converter, and how engaged it is. It is not a linear relationship. The more RPM the more engaged the torque converter will be once it's loaded by putting it in gear. This means less RPM drop at low RPM, and more RPM drop at high RPM.

Speaking of, how does the transmission shift? How is the fluid? Does the torque converter feel too tight when it's cold and you're driving? Does it ever stall when coming to a stop (like it would if you had a clutch and didn't push it)?

[MyToy]

Hey VanCo:

Transmission has really been fine.It had a leak and was fixed plus the round plastic balls were replaced.

It never stalls so long I have the idle high enough. Again, once she gets down to under say 700 to 900 she shakes real bad. Once over 1K she smooths out. So when I set the idle I generally set it when I see the water temp at 180. Then set it for 800. She shakes a little for sure. In drive she shakes much worse and the van moves with little jumps during between shakes. Then after 20 minutes on the highway I can come off an exit to stop and she is at about 950, put her in park and she climbs to 1600.

I really think the transmission is OK.

I did do a test reducing the idle after she got up high yesterday. This time it was about 1600 rpm. So I stuck my screw drive in the hole and turned it until she came down to 800. The screw bottomed out and it started shaking again. So the shake is there no matter. When hot and in drive with brake on she idles at about 900 with a small shake. So I can drive here all right but man if I shut her off or put in park getting her back in drive is like I launch off the ground like the picture of your van here in your ID.

Suppose to rain like hell tomorrow, so I will plan on some time to see if I can find why it is so high.

Next week I plan on bringing her over to a muffle shop to have the O2 fitting installed also.
By the way I found this 5 wire. Unlikely I would permanently install. Will only use it to get the van fix.

5 wire O2 https://www.amazon.com/Wideband-Oxygen-Sensor-Ratio-1000MM/dp/B01N4KJHZR/ref=asc_df_B01N4KJHZR/?tag=hyprod-20&linkCode=df0&hvadid=331942329025&hvpos=1o5&hvnetw=g&hvrand=4279834742786293962&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9011520&hvtargid=pla-653823620285&psc=1

Just have to find a gauge

MT

[VanCo]

I've only bought the wideband O2s as a kit with everything needed. The components are sold separately though. Just make sure you get the right gauge controller to match that LSU 4.9 sensor.

The air temperature in the AFM will be affected by heat soak in the engine compartment. It'll give a different reading during warmup without driving, and driving for a while (normal due to temp change). If the sensor is bad it could be giving the ECU an erroneous value once warmed up. Just an idea.

[MyToy]

You mean the Temp sensor in the AFM?

I would have thought that since it is in the air flow channel inside the AFM the incoming air would keep it at close to ambient temp. If I am not successful with leak tests and freeze tests I may just order the rebuilt one.

Thanks

MT

[VanCo]

Yes the air temperature sensor in the AFM. For the most part the air temp will be close to ambient, however; that will change the longer you drive and the more the engine compartment, AFM, and airbox become heat soaked.

[MyToy]

Interesting for sure. I did make some progress yesterday. I tried the butane approach sniffing out the leak but I felt I really needed to give it some rocket fuel. So I used starter fluid this time. Being very careful I shot each air hose one at a time. I also shot the entire mixture control units seams and bold, and the entire air connection to the AFM.

I found on the cold air bypass a 400 rpm increase when I shot the hose that goes into the steel tubing that goes up to the intake manifold. I chopped it back, used clamp and that stopped that leak. It did not drop the RPM at all and it still shakes a bit. But there is nothing else to check but for the AFM. If I buy a new one, it may solve this but still may be off the 14.7 ratio I am looking for. No way I would crack that one open and lose any kind of warranty.

So I think over the holiday weekend I will remove the AFM and inspect it through and through. Plus I can see better what I will have to do when I adjust the mixture. That Temp sensor inside I could also test to see how it response with difference heat conditions.

Keep plowing forward

MT

[MyToy]

More updates on this.

I found one time I shut the engine off I heard a small little poof somewhere on the top side of the engine.

Close examination I found one of the rubber washers used for the valve cover acorn nuts had melted and was almost sucked into the valves. This produced an area around the stud that was not sealed. So I replaced with a new rubber washer and the poof went away. Along with that the shakes reduced by better than 50%. I tested the theory by removing the oil cap and the same thing re-occured. This is part of the EGR system and had an effect on the idle.

Now I am down to about 800 RPM with almost no shaking when up to full operation temp.
Although when cold and after the cold start air bypass closes the idle goes down and it begins to shake again, but not as bad as before. Still causes the van to jump intermittently when put in gear. Give it 5 minutes of run time the shaking just about goes away.
I then monitored the voltage drop across the Temp sensor to see if that number was in line with the cold start shake. When cold it is about 2 volts. At full operating temp it drops to about .43 volts DC.

So I thought maybe this was a bit off on timing and voltage so I induced a change with an additional potentiometer so I could manually reduce the voltage on my own.

This proved unsuccessful. It made no difference.

So now I am down to a near stall just after the cold start air bypass turns off.

I am sure I am being super anal on this but I am so close of having it perfect I will continue to seek out more issues.

I will have the O2 sensor installed now just to see how that looks now with it running the best since I rebuilt the engine.

But she is really nice at full temp with an RPM at 600 in drive.

What still puzzles me is the more often then not a hard shift into gear even at 800 RPM idle. This may be still another issue with a transmission issue.

It is real nice to drive at 80+ MPH and come to a stop and she hangs right in there at 600 RPM without the tach jumping from the previous shaking issue.

Will keep the updates coming in as I move forward on the O2

MT

[originalkwyjibo]

Sometimes in our diagnostic quests we overcomplicate things. I am frequently guilty of this myself. You had a vacuum leak. Not where you would expect it but a vacuum leak nonetheless. I had started to suggest this awhile back but never posted it. You had sprayed all your vacuum lines and intake gaskets more than once with no success so I never mentioned it. It sounded too simple but my gut kept telling me vacuum leak. You introduced air behind the throttle plate that the idle circuit in the computer couldn't regulate. The signal from the oxygen sensor indicated a lean condition so the computer added fuel to correct it which increased the idle.

[MyToy]

Yep, sure wish that gut feeling go through, would maybe have saved me some time. VanCo was a big help also providing me all the other alternatives.

More test runs today with consistence results. So it is not changing its operation much at all now except for the idle differential of 300rpms and the shakes when cold start up. Have to feather the gas when stopped during this time period, again only 5 min or so.
In your opinion, is 300 within tolerance for this vehicle or should it be better?

I think if I find this small issue it will correct both the differential 300 rpm and the shaking as well.


This all may come out with the O2 numbers also.

We shall see.

MT

[Burntboot]

MT - did you replace just the one melted grommet/washer?

If one was compromised, there is no reason to suspect the rest are still good
The fact the idle smooths out once fully warmed would make me think there are more (small) leaks that abate once the rubber expands with heat

As far as it clunking into drive, have you checked motor mounts and U-joints (recently)?
Mounts can separate, allowing the engine to flop around some.
With compressed mounts, the engine sits lower in the chassis and can cause clearance issues resulting in vibrations being transmitted into the chassis.

When I replaced mine, it was one of THE most rewarding repairs as it solved several issues, all at once.

[MyToy]

Great Points!!

Both motor mounts and drive shaft have been replaced.

I did check the other 2 rubber seals and they are fine.

I may go back and shoot all of them again to see if I missed one.

Transmission does not clunk when first setting to drive however after I am use the van for a while it will clunk event when at 800RPM.

So another strange issue.

Thanks for the suggestions

MT

[Burntboot]

I know this doesn't help you, but it sure is nice to know that I am not the only one in the world that suffers from odd problems, that aren't easily resolved.

Last straw in the box
- How is the transmission mount (aka rear engine mount?)

[MyToy]

Yeah, same goes for me. I am honored to be part of the club:LOL2:


As for the mount.

It sucks. It is the one weird one that mounts from the top with a single hole for mounting.

I was going to change it but could not find.

It looks like this. It has some cracks and is no doubt original.

[MyToy]

Just wanted to keep all of you updated on my idle issue. The plan was to install a wide band O2 sensor and mixture gauge so I could adjust the mixture correctly . Well to get that done a Bun has to be put into the exhaust pipe. So I went to a shop and they noticed that I had a leak at the junction from the front exhaust pipe to the manifold assembly. Turns out the meat ball that install this warped the flange that mounts the pipe with will cause the donut gaskets to fail in less then a year. So I have to fix that first. Can't find one anywhere. So my intension is to remove it and bring it to a machine shop to have the flange replaced or planed. Once completed the bun will go in an I can make my adjustment.

Just wanted you to know I have not died yet:LOL2:

[MyToy]

VanCo and crew, the verdict is in. Installed the Wide Band sensor as instructed. See photos.

When first started or idling it showed 18 to 19. 19 is the max the WB D2 will go.

Then, once on the road and cruising down the highway it drops to 14.6.

Any thoughts on this? Is the rich 18 to 19 screwing up my idle? If so then if adj correctly I would screw up my cruise, right?

[VanCo]

The higher the number the more lean. For example 18 parts of air to 1 part fuel vs 14.6 air to 1 fuel. More air is leaner. Anything over 16:1 at idle on these engines causes a sporadic lean misfire. 18:1 would cause a pretty bad idle, and it really wouldn't want to run.

Usually with readings like yours you want to look for vacuum leaks first as well as a host of other things. 99% of the time that's the issue, but I know the back story so we can go straight to messing with things the factory says not to touch.

First, when cruising does the wideband bounce extremely quick between 14 and 15, or does it just sit at 14.6? When floored for more than three to five seconds does it go into the 13 range? When cruising and you lift off the gas (deceleration) does the air fuel go into the 19 range? These are important details that help determine if the computer is controlling the fuel in open or closed loop, and if the TPS is working correctly.

The AFM has and idle air fuel adjustment. It's technically the only "serviceable" adjustment on it. This adjustment does slightly affect cruise, but only if a drastic change is made. Also, whatever change is made the ECU should compensate in closed loop.

There is a small round aluminum block off cap on the top of the AFM. Pop that off, I drill a small hole and pry it out. There is a flat head adjustment screw inside. This screw basically allows air to bypass the metering vane. Essentially it's an intentional vacuum leak. Close off the airflow here, more metered air, which means more fuel. Open it up, less metered air, less fuel. I don't remember which way is what. I like to write down how many turns it currently is from fully bottoming out. That way I can return to factory if needed.

The computer controls the injector pulse width within a given (small range) percentage to achieve a stoichiometric air fuel. The base starting point for this is the fuel table (what it directly references for open loop running). If the deviation between fuel table and reported air fuel is too large, the ECU cannot compensate. When setting the idle you need the ECU to supply its programed pulse width, and not be trying to compensate as you adjust.

I would only make the adjustment if you know the computer goes into closed loop when warm (but is not currently in closed loop). Also, you want to adjust it to 14.7 in open loop, fully warm. The best way to ensure the computer is running in open loop on preprogrammed perimeters is to disconnect the oxygen sensor while making the adjustment.

As a best practice document all changes in detail, just in case you need to undue what you did.

In addition, do not freeway cruise or wide open throttle at anything above a steady 15.0. oscillating up to 15 and back down is fine. You just don't want to run it loaded and lean for any amount of time. Doing that can mess up engine internals.

[MyToy]

Thank you for your input VanCo. I don't want to tell you what I went through to get that Bun put into the exhaust pipe.:wall: Wow, the amount of data learned from this exercise is fantastic.

I guess I must have got the number wrong. So now I know, low is rich and high is lean.

I will have to get all those numbers for you today. I will log them down as I use the van.

I will get as much detail as I can.

Thanks !!!!

Mt

[MyToy]

VanCo:

Ok, did another run of tests both to and from work yesterday.

When cruising it is pretty steady at 14.6. Ever so ofter it will pop up to 15 but not as much as it pops down to 14.5.
When floored for 5 seconds eventually will hit 13.
When let go it very quickly goes to 19, then to 18 and back and forth.

Then of course at idle she will stay at 19.

What is your take on that?

MT

[VanCo]

Everything sounds good (except idle), though it's interesting that at cruise the readings don't bounce back and forth more often. This could be due to the placement of the wideband O2 bung, which is fine, just interesting.

There is a way to monitor the reading coming from the factory O2 as well. You can tap into the signal wire going to the ECU and connect it to a narrowband O2 sensor. I had both a wideband and narrowband hooked up when I was tuning my AFM. This told me what small changes the ECU was making to try to achieve the proper air fuel (and that meant it was in closed loop), and the wideband told me what the air fuel actually was. With this information you can lean, and richen until the ECU cannot compensate any longer. This helps determine the limits of the ECU so that you can tune the middle of these limits. I don't think a narrowband is totally necessary, but it is useful and interesting. It's also useful in determining the health of your oxygen sensor.

Here is a video from a few years ago. In it I touch on the wideband and narrowband. Don't pay much attention to the specific readings; this was post severely modifying the AFM and fuel system. It wasn't perfect by any means. https://www.youtube.com/watch?v=pJduqIX3n0Y

At this point you could unplug the factory O2 sensor, warm it up, and drive around to compare readings. With the O2 unplugged it should run more rich at cruise than when the O2 is hooked up. This forces the ECU into open loop, and to use the preprogrammed fuel table only.

You can also pop that idle cap of the AFM and try to get that idle number to 14.7 with the factory O2 unplugged. Just document changes to the screw.

Most wideband O2 controllers have a PC serial connector so that you can log your drives using a laptop. Making that feature work might be helpful too.

[MyToy]

Nice video VanCo!

OK kind of sorta worked. Did what you said and removed the O2 sensor after van was hot, right after highway driving. Removed adjustment cover, just popped that baby off just like you said.

Counted my rotations, 3.5 turns to bottom. Backed it off, ran the van. Let it stabilize a bit and went for the adjustment. It was not super effective but it did reduce the idle mixture to about 15.5 after letting her settle down. Howeve; that is with the adjustment all the way down. Can't go no more.

The idle went up a bit. Reconnected the O2 and it stayed about the same. Took it out on the road and she continued to run very smooth at 14.6 at 80MPH. Stopped to idle and she hung in there about 15.3 to 15.5. A hell of a lot better than before. Need to do a lot more driving to see how it response to the shaking. I am going to reduce the idle down to see if the shaking remains. Will let you know.

MT

[MyToy]

Final on this chapter. The mixture adjustment that VanCo brought to the table has worked remarkably. I was almost ready to throw in the towel and just live with it. But now, after a week of use, it maintains performance at idle and the heat soak issue has reduced by almost 80%.

Job well done. Now it is off to my next improvement and that is the hard ride. I am off to the suspension areas of the forum.

Thanks Again
MT

[timsrv]

:thmbup: :dance2: :dance1: :thmbup:

[VanCo]

Super awesome! I'm glad it helped!

[Toyota2RZ-E]

I had a similar problem turned out to be leaking diaphragm within the aircon idle up vacuum device 88606D located on the throttle body.
Took some time to find.
Suck on the hose connected to the vacuum chamber of the device, there should be a vacuum ie no contentious flow of air.
Regards Mike