Hesitation / Rough idle only when cold

[ratatouille]

Ok. Had code 5-1 and 2-5 for a while w/o van running too bad beside poor gas mileage. Van started running really crappy a few weeks back and so I decided to finally dig into the work. Just removed throttle and replaced bad TPS and also did the o2 sensors, codes cleared, but van still has terrible hesitation and lurches when I try to accelerate and doesn't sustain a good idle, but only when engine is cold now , after sitting all night. Once engine gets warmed up it goes away and runs great the rest of the day. Not getting any codes..just a constant flashing.

Any help is much appreciated. I've looked through several other threads related , but I really have no idea what to start looking at first.

-Rat

[timsrv]

Hi Rat,

These type issues can be hard to diagnose, but if the current problem is different than before you worked on it, then the 1st thing to do is recheck your work. Since the throttle body air tube was disturbed, I'd start out by checking it for cracks. Cracks in the air tube are not always obvious. I would let the van idle, then grab ahold of the air tube a give it a squeeze. If it's cracked, squeezing the tube should open the crack and cause it to stumble or die. I would also check the tee that attaches to the bottom of the air tube. The back of that metal tee attaches to a 3/4" rubber hose/elbow that goes to the air valve. It's really easy to knock that one loose without noticing. It's also common for that hose to become brittle and crack (especially during other work), so check for cracks in it too. Other than that, make sure all the vacuum lines are hooked up and not cracked or otherwise damaged. Since the problem is worse when it's cold, check the connectors for your cold start injector and the cold start injector time switch. If these or any other connectors/sensors are damaged, then replace/repair as required.

If you're overdue on any other maintenance/tune-up issues (spark plugs, distributor cap, rotor, filters, etc), then deal with these things so you can rule them out. If you don't know when they were last replaced, then replace them and at the very least take these possibilities out of the equation. If none of this provides a remedy, then post again and we'll look at some of the other less likely possibilities. Tim

[ratatouille]

Thanks Tim. This is same issue I've been chasing down. I've recently replaced spark plugs, air filter, the intake tube is new and all vacuum lines are fairly new and were inspected when I did the TPS work with throttle body removed. But I'll go back and double check everything is where it should be..

Originally I thought the issue was because I was getting o2 sensor code and TPS code. After that work was done I'm still have same problem. The longer the van sits, the colder it is, and the worse it runs, until it warms up then it runs normal w/o problem. I thought I read somewhere on TVP related to my problem about a cold temp sensor? being bad. But TVP is down again and I can't remember what it had said...

[timsrv]

Typically when the ECU temp sensor goes bad, the van runs like crap all the time. I guess it's possible for it to send bad information that's within normal parameters. In theory, if it were to send info that the van was warm, when in fact it was cold, then I guess that could explain things (kind of a stretch though). When it comes to old vehicles, unless you know when things were last replaced or serviced, my attitude is to just replace anything that I think could be an issue (within reason). That sensor is only like $20 or so and only takes a few minutes to change. If it's original it's already had a long life and it's one less thing you'll need to replace later.

Other things I find extremely useful are spare parts. I have a few parts vans and even then I'll occasionally check eBay for extra stuff like distributors, igniters, ECU units, ETC. When the price is right I'll buy. I like to have 2 of each of these parts. Most of them were purchased for less than $20 each. When I'm having a "hard to diagnose" issue, I will swap these parts one at a time to rule them out. Until about 5 years ago I'd never had a bad ECU, but over the last 5 years I've had 3 fail. I haven't had one yet that prevented the van from running. Just problems like hesitation and rough running. One wouldn't read the signal from the o2 sensor. The result was a constant trouble code, hesitation, poor power and poor economy (I went through (2) o2 sensors before I figured that one out).

A good tech shouldn't need extra parts to help diagnose, but they sure take the guess work out of things. With the availability of cheap used parts, my recommendation would be to find some cheap replacement parts to swap in. You can't always count on used parts to be good, but even if you get a bad used part, the problem should at least change (the possibility of a bad part is why I like having 2 of each part listed above). Tim

[ratatouille]

Tim,
Thanks for input. A new baby at home has put things on hold for a bit. Digging back into the issue now...Sorry for delay. Reading through other threads if i remember correctly, folks with similar symptoms seem to mention before issues arose, they had used a fuel solvent or the like. Speculating at this point, but I did use Seafoam earlier this summer after reading people enjoyed the results. Now I may be having a fuel related issue? I won't know till I start doing more investigating... But wondering if it knocked something loose and fouled the fuel pump or filter or even made it too injectors... Do these components tend to warm up and might operate better after a few minutes under load if they are fouled up?

Either way I'd like to tackle sensors/connectors like Tim mentioned first. Looking through the manual and remembering what others have said through other threads, I had trouble finding some part #'s and what folks recommend for these following components (Sorry, I know it's probably a short search function away but my internet keeps going on and off..ug! ) Any help is much appreciated, here's what I'd like to start to check/replace to troubleshoot my problems :

Cold Start timing switch-
Idle-up temp switch-
BVSV-
Spark plug wires-
Distributor cap & rotor-
Coil-
Fuel filter-
Fuel pump-


(ECU temp sensor, TPS, Oxygen Sensors, air filter, spark plugs, and a few other items recently replaced with-in 3-5,000 miles)


I have a Napa store around the corner from me. I also have good connection through Toyota for pricing on components that are a must for a part , but it's a long lead time for me to get parts sometimes as they come from cross country at times..

[ratatouille]

...my internet is still on and off. Any help with part numbers would be huge to trouble shoot rough running issues... Also this last tank of gas I got about 16 mpg. Really need/want to bring that back up... THX

[timsrv]

There are part numbers posted all over the forum. Are you saying you can't use the search feature? There are also sites like www.ToyotaPartsZone.com and www.1stToyotaParts.com where you can look up your own numbers and even order them at discount prices. When I need part numbers I search this site or one of the others mentioned above.

I know I used to post a lot more frequently and I used to spend a lot more time posting part numbers for people, but this is based on my "time availability". FYI, I am working up to 14 hrs per day and don't currently have much time to post (sorry). This is something you should learn to do. If you don't have internet, then this site (or any other) cannot help you, but I see you are posting . Another option would be to call a Toyota parts dept and have them get you part numbers. These guys are paid to do this, but you will need to invest the time and effort in a call.

Okay, so I've worked a long day and I'm grumpy.........sorry. Since you are a contributing member and you donate to the site (thank you), I will take some time and search for you.

[timsrv]

Okay hear you go. If you want to go to the original threads, click on the little blue arrow in the upper left of each quote. Tim

Cold Start timing switch-

(Cold Start Injector Time Switch) Just unscrew the old and screw-in the new. This goes into your cooling system so you'll want to do a leak check after (with engine hot) to be sure it seals up. Unfortunately this is an expensive switch. Depending on where you purchase, aftermarket and OEM will cost about the same. Toyota part #89462-20020 has the MSRP of ~$190, but some of the internet discount Toyota parts outlets will sell it for ~$140. Beck/Arnley part #1580034 goes for ~$155 on www.rockauto.com. If Toyota still has these I'd recommend ordering from them. It's not likely your local dealer will have this in stock, so you might as well save the $50 and order on-line. For us in the PNW, www.1stToyotaParts.com is probably who I'd recommend. Tim

Idle-up temp switch-

This has been discussed many times. This switch is WORTHLESS. If it's leaking coolant, pull it out and replace it with a plug, then take the wire and connect it to ground. If it's not leaking, leave it there (it's still useful as a plug), but take the wire off it and connect the wire to ground. Doing this will trick your ECU into thinking the van is running hot. It will respond by boosting your fuel pressure for 2 minutes after each start-up. This will help combat "heat soak" problems.

BVSV-

BVSV (Bi-metal Vacuum Switching Valve) Toyota part #90925-05017 otherwise known as the "Oh crap I broke it valve". The plastic nipples on this valve get extremely brittle from the heat of the engine compartment and will break off if you look at them wrong. If you're pulling the head it's almost a given this valve will break. Last time I purchased one was about 2 years ago and at that time they were still available through Toyota. The valve's mission in life is to inhibit EGR operation when the engine is cold. These run about $40. Here is a picture of one.

Spark plug wires-
Distributor cap & rotor-
Coil-
Fuel filter-

9091922357 Genuine Toyota spark plug wire set
1910171010 Genuine Toyota distributor cap
1910273180 Genuine Toyota rotor
2330079055 Genuine Toyota fuel filter

Fuel pump-

Toyota pumps are very expensive (probably well over $400 by now). A possible alternative is aftermarket. I recently tried an aftermarket fuel pump from eBay. Normally I'm pretty strict about keeping my vans Toyota, but this one is a beater & I don't plan on driving it for very long. The pump (US Motor Works #USEP8023) cost $37.98 & had free shipping. It came quickly & included the pick-up filter & the outlet hose. Anyway, I was very impressed with the "perceived" quality & it looked/fit exactly like the original. So far it's been performing flawlessly over the past 6 months/6k miles. It was such an exceptional value I picked up a couple extras for spares. One curious thing I noticed is the application list for this pump is massively huge. It fits around 800 different makes, models & trim levels (including Dodge Sprinters) & is also used with diesel engines. Here's a link to the pump: http://www.ebay.com/itm/US-Motor-Wor...d8c0c1&vxp=mtr. Tim

[ratatouille]

Tim, thanks for your time. Sorry for delayed response. My job takes me away from home for days at a time and at time of post I was trying to use a tablet with difficulty staying connected to the internet as I tried searching around for part #'s, and more so, information on aftermarket options vs. going Toyota. I wanted to try and order a few parts before I came home. At the time I did manage to post to a thread as it was quicker to access than sifting through posts. Either way, I didn't mean to pester you Tim, I guess I just assumed there was big ol' room full of TVT reps in suits and ties smoking cigars, ready to respond at a moments notice. Like a big computer room at NASA monitoring a space shuttle launch. ha.

Annnnyways, I've used the sites you mentioned numerous times now Tim, thx. One question I do have (for anyone out there, not just Tim...) is part number 89462-20020 (cold start timing switch) is coming up on a few different Toyota parts websites as NOT compatible with my 88 4wd le. Is that accurate?..or will this part number be ok? I'm seeing # 89462-30011 instead....but I don't think that's the same switch? from the diagram shown it looks like it's in a different location...Just wanted to be sure as this part is not cheap.

[timsrv]

No problem, sorry about neglecting the site and not being here. I'm not sure how I came up with that part number (originally), but I just double checked the EPC for an 88 van and found you are indeed correct. If you're going to purchase this for an 88, I'd definitely go with the 89462-30011. Tim

[ratatouille]

Update on my problem... I'm still chasing it! BUT, I'm certain now the culprit involved is MOISTURE. The ONLY time I'm having this problem I'm noticing (rough start, up & down idle, hesitates and lurches like it's running out of gas when accelerating) is when there is high humidity over night, like foggy dew or mist, or when it rains. I don't have this issue driving around during the day if it becomes wet. Unless I hit a good puddle, then it will bog down like water got into something it shouldn't have. More common though, when the van sits over night and there has been any kid of dew or moisture in the air, upon initial start this is happening. I'm baffled as I've crawled and looked around to see where there might be moisture settled underneath or in engine bay on components, but nothing obvious. I don't know what to do next...any suggestions ?!

[originalkwyjibo]

I have read some discussion of moisture issues under the distributor cap(But couldn't seem to find the thread just now). Perhaps after the next humid night you could take a look there. It may be that with the heat of some time running it is evaporating then over a humid night the moisture could be pulled back in as the engine heat cools.

[timsrv]

I would change the distributor cap, rotor, and make sure the rubber seals between the cap and the distributor are there and intact. I might even replace plug wires. I had a similar issue once. I had an upper radiator hose spring a leak and it sprayed coolant all over these parts. Ran like crap, but when it dried it was fine. After that there was no issue except on the humid days. The ethylene glycol was still there, but had dehydrated on these parts. In high humidity conditions it would attract moisture and dew would form in these sensitive areas. I could have probably washed these parts, then dried, and had success, but I chose to replace those parts and problem went away. Not sure this is your issue, but when it happened to me, that's my best guess as to why. Tim

PS: could also be a faulty coil, igniter, or maybe even an ECU. Sometimes these electronic things will only mess up under certain conditions. Tim

[ratatouille]

Found some time to dig back in over this weekend to hopefully squash the issue. Thanks for input. makes perfect sense as I have had a leak there in the past. Everything has been swapped out except coil cap & rotor. My kids tore up my manual, so at the moment I can't ref it. Can anyone point towards good instruction on how to replace properly. I've got to check timing after I put new in correct?

[timsrv]

If the timing was set correctly before, then it won't be messed up if you're only replacing the cap & rotor. If you're also doing the coil, then IMO the distributor should be pulled. Others here have done the coil without removing the distributor, but all complained about it being a PITA. If you pull the distributor, you'll need to check timing when you're done. Several good threads here about how to align distributor and set timing. After it's set, be sure to pull the jumper and recheck to insure the electronic advance is working. Tim

http://www.toyotavantech.com/forum/s...and-adjustment

[ratatouille]

Well finally I think I've got the issue solved. After going component by component in hopes to know exactly what was going on, I think I had more than 1 issue to begin with. Either way I have peace of mind now I have several new components operating correctly. ha. So, thank you for leading in the right direction. I replaced distributor cap and rotor and so far I'm not experiencing the issues any more. All though I haven't seen too much moisture yet..but seeing the condition of cap and rotor terminals it was probably to change anyways. See pictures.

[TLett]

Ratatouille,

Sorry to resurrect an old thread if that breaks protocol, but I figured it would proved I searched for an answer, and this is the closest I came. Did the that fix you puddle problem? Mine does the same, and I've assumed it was on the driver's side, since driver side puddles seem to be cause the most problems with the least puddles, but I'd be thrilled to take the search in another direction if that sorted it for you. Plus I've still got the passenger seat off after replacing my timing gaskets.


Update: After Tim helped me figure out the loose connector by the exhaust was my TPS connector, I’m thinking splashing that guy might have been doing it. I’m hesitant to go puddle searching just to test, but next time it rains hard I’ll update this thread if it was a fix.