Jay351

So my truck started to do this a few years ago, a good friend of mine told me it was probibly dirty injectors that were sticking. The problem went away for a long time. In the past year it has returned, and getting worse.

It used to do it after a long time of cruising at set throttle position, now it wants to do it almost all the time.

When driving and holding a set rpm/speed, if I pop the clutch in and let the throttle out, 9x out of 10 the rpms will stay up, throttle completely off. If I give the throttle the slightest blip, it will knock it down to idle.

I have cleaned the throttle body (when I had it off to adjust the TPS). I have NOT touched the wax valve, im not sure how to go about cleaning that.

So what do you guys think the problem is? It seemed to go away after I dumped some seafoam in the tank and the brake booster...

Its getting really anoying, it will do it when I let off the throttle to let the truck engine brake. It just keeps going! Almost sent me into the curb once..

vital22re

iTrader: (2)

it may be the dashpot thats on the throttle body. If its clogged or sticky it may not release the throttle valve.

toyota4x4907

If the injector(s) were still squirting when you let off the gas (closing the throttle plate) wouldn't it essentially flood the engine, bogging it down? Seems like its still letting air in. Dashpot could be the culprit, as could the AFM (sticking open) some crack in the intake ducting ( seems less likely) My guess is something to do with the throttle plate. Its funny because My 22re will sometimes idle high or low at idle and if I just barely tap the gas, it will idle at 800.

DupermanDave

could also be your throttle cable getting frayed and stuck.

Justinlhc

I had this problem, but it would only stick at like ~1500rpm. I sprayed WD40 all over the throttle linkage on the throttle body and it went away.

Jay351

I have lubed the dashpot, it seemed a little sticky, but seems to be smooth now.

I sprayed all the linkage on the TB

I cleaned the butterfly

There are no leaks in my intake

AFM tested fine, and works smoothly

throttle cable is smooth, when I let off the throttle the pedal comes all the way up, so I don't understand how its staying rev'd up....

Justinlhc

I had to adjust one of the allen screws, might have been the dashpot? I'm not sure but it seemed like sometimes it was holding the throttle open a bit, too.

Jay351

well, it doesnt just hold it open a bit. It'l keep the truck rev'd at whatever rpm's I was crusing at with light throttle. From just over idle to almost 3,000rpm. Never stays higher then that, but thats probibly because I never cruise at light throttle that high.

It will not do it if I let off the throttle hard..most of the time. But the problem is getting worse.

DupermanDave

just in case it's a frayed throttle cable, you dont have to buy the dealer's $90 cable. Autozone has a universal one that looks pretty nice for $20.

It also may be the butterfly valve sticking. I have a whole "high idle" thread where the problem turned out to be the butterfly valve sticking open and would not seat properly. Had to get a new TB. No amount of oil made it swivel and seat smoothly.

Jay351

Aww, too bad we don't have autozones up here

Well, I can't conferm that its not the butterfly, since I can't see inside the TB when im driving. It only happens when im driving and I can't replicate it when im stopped.

The butterfly seems to seat just fine in the TB...

Jay351

So I will be taking the beast on a trip up north on tuesday. A nice 2.5 hour drive up the mountains. Its usually the worst when on the hwy, so we will see how it goes.

perhaps I will shoot some seafoam into the intake before I go..

Flash319

I would take the dashpot off to eliminate that as the problem. The only other thing I would think except for the obvious which you have looked at is the AFM sticking. Do you have a spare one to try?

Jay351

No spare afm, but I can get one. If you guys realllly think its the afm, I will get a spare and run it... But it tested fine, and the flapper door moved with little resistance..

Flash319

It seams odd since the throttle cable and everything is good. I would not think that it is the injectors because if one of them stuck open it would run like crap not rev up. Least I don't think it would but I guess it is possible.

I would start eliminating things and the AFM and dash pot would be a good start. YOu also have a built in cold idle valve since its a 91 so if everything else is good I would look there. The only thing with that, is I would think that if there was a problem there is would be all the time not just some times and at curtain throttle positions.

DO you have AC? Maybe you have some vacuum lines hooked up wrong or there is a problem with the AC idle up valve/ PS pump vacuum hoses to it.

Lumpy

I'm thinking it's in the TB somewhere. When you have a moment let the truck warm up, keep the hood up and shut it off. Hold your foot on the skinny peddle about where you would normally while cruising, (fun part now) Stay like that for about 8-13 minutes (ok 10) and then look under the hood to see if it's sticking. See if the TB is stuck open at all bump the butterfly and see if it jumps at all.

If that does not work have some one sit in the truck and keep it running about 1800 for a minute or two and then have them let off the gas as you watch everything move to where it should be, might see the dashpot sticking.

Jay351

Im pretty sure the throttle cable is good, because when it happends I have tried to pull the gas pedal back, but its as far as it goes.

The AFM tested good with the FSM test, and the flapper is smooth. The dashpot is smooth (I lubed it) and doesnt stick, at least it didnt when I was messing with it.

The Cold start injector is not working right now. I had a hunch it wasnt working so a few months ago I ohmed it out, it had no resistance. So Im assuming is has stuck. I just unplugged it since its summer...
Should I look into this as a fix for the idle problem??

I do have A/C but it hasnt worked in years. I havnt touched it... The truck doesnt idle up when I turn the wheel, is this a problem?? I did swap the pump last year with a 2wd pump. The hoses and lines were pretty cruddy but they seemed to work...

I cleaned the TB and butterfly again today, it was a little dirty but nothing amazing. I cleaned with deepcreep (seafoam) and I shot a little into the ports in the TB..


Thanks, I will get somebody to give me a hand!
The butterfly seemed to be fine, its pretty clean (now) and is smooth. there is some side/side movement where the spring is on the TB... I didnt think much of it though...

Lumpy

The cold start injector should fix your idle issue if it does not have a high idle.

As far as the side to side, not sure...Maybe there is a small wear spot on the TB... Hard to tell with this one.

DupermanDave

[YOUTUBE]http://www.youtube.com/watch?v=gkKrrsnd8pM[/YOUTUBE]

This is how much play I had (way too much)

Jay351

Well, I also have a TPS wiring problem, one of the wires has over 5.5 ohms of resistance. So The motor tends to vary its idle from stop to stop. Latly its been idling around 500-700 with it going all the way down to 200rpm if you are sitting ni a drivethru for awhile...
This also prevents the motor from idling down so you can set the timing properly. Truck is running rich right now (I can smell it). Still gets 16-18mpg no problem.

Im not sure what to do with the CSI, im sure its filthy and stuck open or something. Should I just get a new gasket, take it out and try to clean it? I was going to buy a used one and use that instead, if I can find one...

After driving around for 20 mins today to the carwash, the problem seems to be gone.. for now.

Perhaps the little openings inside the TB were clogged.. Or its just super sensitive to the little bit of gunk that was in there...

Jay351

Hey duperman. Mine is maybe half of that or so. Its got somemovement but not that much.

how much is too much?