very rough idle, cutting out immediately: distributor? vacuum?

hi folks,

well, i have some questions. thanks for offering your experience on working on these vehicles.<br><br>(this is an 84 automatic.)

short version: i had a broken (shattered) distributor rotor. with new rotor, the vehicle started, but would only stay going with heavy foot on the
gas -- letting it idle would cut out immediately. fiddled with the distributor angle back and forth and found "best" timing (without a
timing light) -- but still cuts out immediately, is very rough, missing, etc.

a mechanic who listened for a moment said it sounded like a major vacuum leak, but there's no obvious sound of air. the infamous
boot from the air filter is slightly perished on the engine side, but seems intact.

to get it home, we adjusted the idle very high so wouldn't cut out when stopped. made it home, engine ran better warm it seems.

what is the best way to diagnose further? brake cleaner all over the air system? EFI diagnostics? are there particular sensors that might be
causing problems? vacuum hoses?

could it still be the distributor? the cap seemed fine, inspected quite thoroughly. timing isn't perfect, obviously, but shouldn't be causing problems this big, should it? how would i troubleshoot the distributor further?


longer story: vehicle is almost 200k miles, has clearly been worked on before we got it recently, not in super good
shape. the automatic transmission has been jerking and shifting late (throttle cable?), and the radiator has been leaking. i was on my way
to replace the radiator with a junkyard one, when i turned left into an SUV. damn.

i was moving pretty slow, and it didn't seem like a major impact. body damage was a few dents in the bumper (passenger side) and on the grill, and broken indicator. but it didn't start at all. eventually ripped open the panel under the passenger seat, discovered the distributor rotor was smashed. replaced that, and then had the immediate stalling problem above.<br><br>the impact, slight as it was, did have some effect on the frame: the passenger door now hangs weirdly, and the "weatherstripping" at the top is outside when closed.&nbsp; how could a slight frame buckling affect the engine?

driving with the throttle screwed wide open (ie. "idles" at &gt;3000 rpm in neutral) was an experience. the engine light came on at times, then went off again.&nbsp; also, the heater seems a bit broken: hot/cold lever seems not to work well, and air temp at max heat is
pretty lukewarm -- probably unrelated? blend door?

finally, i opened the air filter while poking around in there. there's only two clips on it, rather than the 4 there should be. but that's how it was
before, and it worked "fine". relevant?

anyway, any thoughts or suggestions on next step to diagnose the major engine roughness would be wonderful!

thanks, all.
.brush

Hello and welcome to TVT! That's an interesting story. I'm not quite sure how an impact to the exterior of the van could cause the rotor to break, so perhaps this might be a strange coincidence??? The rotor must have made contact with something for it to break, so I think we should start here. Have you carefully inspected the cap and other components inside? Can you see any other damage? Does the distributor shaft have any side-play? After an event like that I would want to pull the distributor and give it a careful inspection. Make sure the drive gear on the bottom is intact (no chips or excessive wear). Also check the sheer pin (attaches drive gear to shaft) to make sure it's intact. You should also check the shaft for excessive side-play and check the thrust clearance. See picture below:

http://i8.photobucket.com/albums/a23...inspection.jpg

After inspecting per the above, if anything is amiss, repair or replace as required.



If all the above checks out okay, you should put the van into it's diagnostic mode and check trouble codes. Please do these things and report back. if the problem still exists I will help you through the next steps of troubleshooting. Tim

thanks so much, tim! really appreciate the response.

ok, here's the report. i pulled the distributor completely out and broke it down. (i'm using the 1986 manual available online, and it doesn't seem to include the connection with what i assume is the vacuum advance -- a physical curved bar that pushes into a double-diaphragm device that runs two vacuum hoses to the engine, and when i push in on it i hear air pushing in the engine. anyway, i went ahead and removed it to pull the distributor off.)

everything seems fine. the drive gears and pin are in good shape, there's no sideways play. i don't have feeler gauge yet, but the vertical "give" seems to be less than half a mm to me.

i also checked the diagnostic code, and it was blinking 5 times -- oxygen sensor circuit. this means running rough or lean, or just disconnected, right? but unlikely to cause this much roughness, right? anyway, how best to test whether it's the circuit (wires) or the sensor itself? and where is it exactly? seems to be kind of in the middle, towards what i'm guessing is the exhaust manifold, but not entirely sure.

one other piece i noticed: the oil cap is loose, and can't be fully tightened (just spins, and then can be pulled out). maybe the cap is too small?? anyway, this must have pre-existed the current situation, but wanted to mention it.

thanks again, tim!
.b

Well I guess the broken rotor will remain a mystery. As long as everything checks out okay I guess it's probably not a distributor issue. Here's a good thread to help you troubleshoot the rough running issue. Tim

http://www.toyotavantech.com/forum/s...lt-HG-Replaced.

thanks, tim. i've been delayed, obviously: other urgent tasks came up. finally got feeler gauge, and confirmed that the "play" in the distributor shaft is just about 0.50 mm, the max allowed. today went to put the distributor back together and try the spark plug-pulling test to see if it's missing -- distributor seemed to go back on fine, but when i started it (with a jump, since the battery has been fading from all this test cranking) two distressing things happened:

1) cranked over, but i didn't hear any firing.

2) after cranking over for maybe 10 seconds, there was an almighty "whoosh!" outward from the main air intake and the interior of the van filled with gasoline-air.

it looked like the "whoosh" came from the where the air intake rubber boot connects to the air filter, which we'd taken off before and might not have been on very tightly. i tightened it, and tried again. same result -- except this time the whoosh came from the other side of the boot, and i discovered that a vacuum hose from the boot heading down then back towards rear had popped off. i've put it back on, and lifted the distributor cap and looked around to see whether that could be causing anything, but i'm stumped.

there is a little rotational "give" in the distributor shaft -- maybe 15 degrees. it seems normal, but i can't remember whether it was there before, nor can i imagine what's causing it. the distributor appears to be fully seated down, implying the rotor shaft is fully seated in the crankshaft, i think. of course, the timing could be completely off -- but i've put it more or less in the middle, which is how it was before. i put the plugs back in 1-2-3-4 front to back, which i think is correct. still, while something wrong with the distributor might explain no firing, i don't understand the vacuum blowing issue -- which is completely new, near as i can tell, since i pulled the distributor.

what would be causing the pressure in the carburetor to get so high it starts popping off vacuum hoses? (is that an appropriate interpretation of what's happening?)

thanks folks for your ideas! this's intriguing, frustrating, and perplexing, i must say. :wnk:
.brush

Quote:

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i put the plugs back in 1-2-3-4 front to back, which i think is correct.

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Is this for the spark plug wires to the distributor? I don't know how it is on 1984 vans'(3yec) but on my 1987(4yec) the manual says 1-3-4-2, I think that's going away from the distributor, can't remember. It's kind of a pain to set timing on these but I did it, so it's possible and with the distributor timing off mine ran like crap. A manual would probably help a whole bunch, if you haven't gotten one yet.
May be a long shot but have you changed the spark plugs since you bought it?

i understand the firing order is 1-3-4-2, but i'm talking about which numbered wires go to which plugs. i looked it up (and it's what i remember was there before), and it says the wire numbered 1 goes to the plug at the frontmost end of the engine, then 2-3-4.

as for timing: what were the key tricks to getting the timing right? without a timing light, we tried moving the distributor back and forth with no noticeable change (better or worse). it's hard to emphasize how awfully the engine was running.

of course, now it's not running at all, with this blowing out of the vacuum system every time i try to start it. any ideas on that, anyone?

thanks!

It sounds to me like you got the distributor in a tooth or two off. This can cause back-fire up through the intake (and that sounds like what you are describing). This is pretty basic stuff but somewhat complicated to explain. The last couple of pages of the IG section in the factory service manual go through this step-by-step. Same procedure for all years and flavors of vans 84-89. Once you have the distributor set in the correct position then you'll need a timing light to dial it in. Unless you have unmarked aftermarket plug wires this part is easy. Engine cylinders are always numbered front to back. (1 being front). Toyota plug wires are actually marked with numbers, so just plug them back the way they're marked. Due to length they're hard to mix-up anyhow (unless you pulled them out of the cap). If you did that then you'll need to set those back up correctly. The manual covers that as well. Have fun. Tim

you're right, it was very basic, and that is admittedly the level i'm working at here. :wnk: so, doing this basic task took quite a long while -- a significant part of which was first finding and then straining to turn the crankshaft while fiddling with a screwdriver to find TDC. but, in the end, all's well: the engine is back to turning on and running roughly.

several comments from this:

1. the screwdriver came up from the TDC-finding expedition with significant black gunk (from the top of the piston?) -- should i be concerned?
2. the spark plugs are kind of dirty, with black gunk again. should i be worried about this? or is it just the result of running so rich and crazy? i figure i'll just replace them anyway.
3. i'm assuming the order of the wires on the distributor end is correct: 1 bottom, furthest from engine; 3 bottom, closer; 4 top closer; 2 top further.
4. while struggling with the engine today, i saw two small parts that seem to be broken. i'm having trouble deciphering the circuit diagrams etc., so perhaps folks on here can help diagnose what they are, and how likely they are to cause some of these symptoms? i figure i'll replace them anyway... (see photos attached, with my finger pointing at the sensor/part. the second two refer to the same thing, but the one with my finger pointing shaded out the key piece, a little tube or something that's disconnected.)
5. also, while taking photos i figured i'd give you a video of how the engine sounds -- see http://youtu.be/Z0NdbZKPIbE. you can hear the struggle to start, the missing now and then, etc. the "ticking" is probably the fan hitting its cowling -- need to fix that. it's super-high revs, of course, because i've got the idle set crazy high (like 3k rpm) to keep it from cutting out. any diagnostic thoughts from this audio? i know it's not great quality, but...

thanks so much, tim and others!
.b

Lol, that would certainly explain it. The one in your 1st picture is the temp sensor for the ECU (basically a thermistor). The van will run like crap with that thing broken. If you can't get from a salvage yard, get a new one ASAP. It's Toyota #89422-30020. The one in the front is a thermo switch and doesn't matter much. If you're having an issue with hot soak it might help if you just cut that wire off and ground it (the wire) to the engine or chassis. Tim

Quote:

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Originally Posted by timsrv

The one in the front is a thermo switch and doesn't matter much.

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thanks, tim! i'll go check the salvage yard pronto. hope that might be it.

just to be sure: is the (broken) device in the red circle in the picture below the one that is the pointless temp switch? it doesn't really seem to have a wire, but rather some kind of tube connected to it -- or rather, two of them, top and bottom, and the bottom one is broken.

thanks!

No, the one circled in your last picture is your BVSV (Bimetal Vacuum Switching Valve). Another common name for this is the "Oh crap I broke it valve" :lol:. This is because the plastic nipples get brittle over the years and will break if you look at them wrong. This valve's job is to inhibit EGR operation until after the van warms up. With it broken like that the EGR won't work and you'll have a small vacuum leak. You may also get a trouble code in your ECU and the van may not pass emission testing. I doubt you'd be able to find a good one in a salvage yard, so your choice will be limited to bypassing or replacing. If you replace it's Toyota part #90925-05017 and has an MSRP around $50. If your on a budget, you could bypass by looping a vacuum line from one metal tube to the other. In theory this will make the van run a little rough when cold, but I doubt you'd even notice (considering you'll be trading up from a vacuum leak).

The ECU temp sensor I was talking about was the one in your 1st picture. This sensor being broken will make the van run like crap. I took your picture and marked it up (so there's no confusion). It's Toyota #89422-30020 with an MSRP around $80. Tim
http://i8.photobucket.com/albums/a23...tempsensor.jpg

thanks, tim. i'll probably just circumvent it for now, see about a new part when i get things running better.

i've got a couple other questions: once i've got the engine able to idle at 750 rpm without cutting out (hopefully with the new sensor), i'll want to finetune the timing. i've never done it before, understand it can be challenging, and with the 3Y i'll have to clamp off the vacuum advance from the distributor -- any good threads i may have missed laying that all out in detail? eg., how on earth can i get to be able to see the timing marks? it's at such a cramped angle, with the fan blocking things -- i barely was able to get a wrench in to turn the crankshaft. ideas? use a mirror? remove the fan?

secondly, i've got a coolant leak/radiator question. we've had pretty variable, major coolant drops -- like sometimes a gallon after a short journey (but sometimes nothing). managed to avoid overheating so far, but curious about troubleshooting the hoses etc. i think it's the radiator, but if i get it out and stick a hose in it and can't find a leak, what do i do? anyway, should i make a new thread for this?

thanks,
.b

Setting the timing is somewhat of a PITA on these vans, but not terrible. Just spend a little time before hand cleaning and/or painting the indicator and the notch on the front pulley and it's easy. I took a video recently while timing a 4y (with electronic advance). The resolution isn't the greatest but it gets the idea across. With yours you don't have electronic advance, so it's a bit simpler. Rather than pinching the vacuum tube I'd recommend removing it and plugging with a golf tee or something (so you don't need to worry about any vacuum making it through). Here's a link to the video:
http://i8.photobucket.com/albums/a23...h_MVI_1489.jpg

As to your other question it's always best to keep these things in separate threads (helps keep the board organized). We've covered this before though. Here's a link to it: http://www.toyotavantech.com/forum/s...gasket-failure .

I realize you're not suspecting a bad head-gasket, but the leak test procedure remains the same. Tim

Yes, with the ECU temp sensor kind of broken or not connecting I believe the older vans will not only run bad but could put you off to the side of the road. That plug came off on me, it bumped off on one of the many lumpy roads out here, and if I hadn't seen the cloud of black smoke behind me I would have thought I had run out of gas. I taped mine on because the plug is broken. When the van is running, unplug it, you'll see. I would make sure the contact there is clean, tight, and good to go before trying to diagnose further -
happy tinkering,
kenny

well, i got the ecu water temp sensor at the u-pick, and it makes a world of difference indeed. thanks tons for that insight -- now i can actually keep the engine turning over below 1k rpm! :thmbup:

the timing is clearly off, quite a bit of missing and unevenness, making it hard to get the idle consistent at 750. i figure i'll do rough timing by ear, then get the timing light in place.

using the 4Y manual (only one i have found online so far) can lead to some strange questions. eg. can't seem to find the isc vsv to disconnect while setting idle. maybe not so important?

the biggest thing is figuring out where the timing marks are. i gather from the manual it's not the driveshaft pulley, but rather the one nearest the passenger side? i've looked, can't find. will have to do more cleaning!

btw, is there a way to set the timing w/o a timing light? i hear some folk do it by calibrating TDC with the rotor pointing at one of plugs... but maybe i just bite the bullet and buy the light.

thanks again, all. making headway!

Here is a picture of a 4y I recently installed. If you look at the pulley and the timing cover you can see some yellow paint. Before I mess around with trying to time one of these things I clean and mark the area like you see in this picture. This makes timing a breeze.......and yes, you need a timing light.

http://i8.photobucket.com/albums/a23...e/IMG_1479.jpg

You also need a manual for the specific equipment you are working on. I took a look and see the 3y calls for 8 deg BTDC @ 950 RPM (with the IIA diaphragm disconnected). Here's a quick snap shot I took from my 84 service manual (I hope it's clear enough to read). I also checked 85 and verified there are no changes between the two. The big change comes in 86 with the introduction of the 4y w/ electronic advance.
http://i8.photobucket.com/albums/a23...e/IMG_1497.jpg

BTW, the manual makes no mention of disconnecting the ISC VSV while setting the timing. Just be sure to disconnect the vacuum advance diaphragm and you'll be golden. Tim

hi tim and others,

geez, it's a challenge to see that pulley! the belts and radiator hoses etc. block things pretty comprehensively. but i finally found the machined notch, and painted it as you suggested. thanks so much for the images -- it must be easy to find the notch when there aren't any belts in the way! and great to get the actual 84 instructions.

so i found the notch, get the timing light set up, and away we go ... but wait! the notch doesn't show anywhere under the light! when moving the distributor, the idle gets better and better as i turn it more and more clockwise, till it can't go further. when i'm at the far end clockwise, i can just barely see the notch at the far bottom of the pulley (ie. around where 30 degrees or so would be), when i turn it back the notch disappears.

is it possible i got TDC wrong (ie. opposite) when putting the distributor in? i found TDC using the screwdriver-in-the-sparkplug-hole technique, which was kind of challenging. i thought there was compression on the #1 plug, but maybe i was wrong...

now that i've found the notch, should i go ahead and re-seat the distributor using the notch-at-0 in order to set TDC? well, i'll try that. strange... :wnk:

well, i pulled the distributor again, and redid the whole seating of it, twice, using the timing notch for TDC and testing for compression with my finger, as per instructions below. then set the drive drill hole with the groove, and the oil pump rotor slot to 30 deg or so, and then set the distributor in. it doesn't slide in super easy -- i have to wiggle it a little -- but it gets in.

but i get the exact same results: when the distributor is rotated as far as it can go clockwise, the timing light shows the notch at around "30 deg" BTDC. if i turn it counterclockwise, the timing notch drops away till i can't see it. (to be clear: the vacuum advance hoses are off and plugged.)

i've included the distributor installation instructions i've got below -- from the 87. is it different for the 84? maybe i should try rotating the slot more vertically (which is what the angle of the rotor looks like when the drill hole and slot are aligned)? anyone heard of this or experienced it? :cnfsd:

thoughts? thanks!

If you have doubts regarding the notch then it's best to pull #1 plug and verify. Just look through the spark plug hole while rotating by hand then use a screwdriver or something to stick in the hole. Now carefully rotate the engine back & forth (by hand) until you're reasonably certain the piston is at TDC (Top Dead Center). Now check the notch and it should be close to the 0 on the timing cover indicator. If it's within a couple of degrees then it's good (a couple of degrees is as close as you can get by checking via this method).

Assuming the notch is in the correct spot it sounds to me like the distributor is still a tooth off. Once that's seated correctly you should be able to set the timing via the light. Tim

PS: The distributor is driven via a helical type gear so this means it will rotate as it seats. You need to account for that while dropping the distributor.