Update: after replacing TPS, cleaning AAV, TB, and other steps, it seems resolved by shortening the return spring (again). Literally the first thing i tried years ago. Whatever!

ok, so the truck is at a shop right now. I went through a dozen threads here, went through the FSM, and gave them a laundry list.

Problem: The truck has been holding high idle. Tap the gas, it comes down. Shut if off while at high idle, then restart, normal idle resumes. Once I replaced the TPS, the surging started. I dialed down the RPMs to make the surging stop. The next morning at cold, the truck would not start until i opened the idle screw back up a little.

I removed the idle screw. It was dirty, so I cleaned it. I set the idle to 850. At cold, it idles fine, but once warmed up, the idle raises itself, and now it's doing the surging. Tap the gas, it comes down.

I asked the shop to remove the AAV or IACV, the thing under the TBI, and clean it out, based on what i read here. Supposedly they have. I asked them to clear out the water lines going to it. They said there are no lines, and its been bypassed. IS THIS MY PROBLEM?

I printed the page from the FSM that describes checking the RPM CUTOFF. They told me they don't know what I'm talking about, saying there's a circuit that MAKES the idle surge when applying the brakes. They want to sell me a brake booster, saying the surging is coming from a leak.

HOW CAN I TEST IF THE BOOSTER IS FAULTY?
IS THERE REALLY A CIRCUIT THAT ELECTRONICALLY MAKES THE IDLE SURGE? if so, SHOULD I JUST BYPASS IT? how?

This is the like the 6th shop i've tried to get this fixed at. Its making me want to sell the truck because i'm just sick of throwing $600 at it every time, it seems to go away until i leave the shop, then it starts idling high again. CAN ANYONE FIX THIS FOR ME? I'LL COME TO YOU, ANYWHERE IN THE SOUTH!

it might be a booster at this point, but it seems really odd my pedal is not hard. I wish I knew more to argue the diagnosis, but i can't. but i'd like a 2nd opinion from someone who owns a 22RE-powered truck.

 

Easy to see if your booster is leaking Air

Remove the line and plug it .

Is your throttle body hanging up or wore to the point the shaft is leaking

I have had my AAV bypassed for years no surging

The idle up VSV for the AC I would think more all the time then intermittent

Now the Rpm will change as the Compressor cycles on and off No AC ??

Are we talking Auto or manual ??

I can`t remember what you have

Is it really a surge the idle just goes up and down in some sort of pattern

 

it's a manual. the a/c does not seem related. it does this with air on or off.

when cold, idles fine at 850, no issues. once hot, the idle will hold itself higher, like 1100-1200. tap the gas and it comes down again. drive a little more, idle sticks high again. When its sticking high, stepping on the brake causes the surge.

the problem isn't the surging. the surging seems deliberate, a result of the high idle condition while warm.

the problem is the sticking high idle. go under the hood, open the throttle by hand a bit, then let go. the throttle does not shut completely WHEN WARM like it does when cold. you have to push it completely shut and it idles back down. Or, cut the engine off, and throttle will close so it idles correctly on restart.

something is holding the idle high, not allowing the throttle to close completely. an amateur's guess would be to try to put a super strong spring on the throttle to force it shut.

i just picked it up. no problems the whole way home, in 30 mins of stop-n-go traffic, at 95* out. I thought it was fixed. I pull into my driveway, cut off the a/c, open the hood and open the throttle by hand. It's doing it again! @#%%^@!! Sticking open, holding about 1200rpm. Must force close the throttle by hand.

that shop wanted to sell me a brake booster. i'm glad i didn't say yes to that. there's nothing unusual about my brakes. i'm going to have to sell this truck as i'm too stupid to own it.

QUESTION: if it was only doing it with a/c off, and not with a/c on, would that be a clue to something?

 

i think that you can disconnect the hose for that at the manifold, for testing purposes.



i tried doing that with mine, but it's a coil spring, with nowhere to really connect a straight spring... you need to find out why it's sticking.

you could try disconnecting the throttle cable at the throttle body, see if the throttle plate slams back without it... if it's the cable, hold it up in the air, and pour some kind of lube down into the cable sheath, then work the accelerator pedal a few times, see if it frees up.

has the throttle body ever been removed and cleaned? usually the tb and the plenum are horribly gunked up.

 

Is the throttle body hanging up?/ I lube mine every oil change or more often.

The dash pot under the throttle linkage hanging up ??

Could be just dirty I have to look I can`t remember if this is vacuum controlled

Might very well be both

Hang in there we will get it figured out.

It is of a Mechanical Nature

 

clean your throttle body.

 

The TB has been removed and cleaned, supposedly twice. The dash pot is new. The cable has been lubed. The air valve has been cleaned too. The coolant hoses to it have been bypassed.

I appreciate the suggestions so far! Anything else you car think of?


I looked at SOLD prices for this model on fleabay and it's very disappointing. I can't afford to sell this truck whole, I'd never get back what I've dumped into it. Which i never planned on doing. When i bought this truck i planned on it being the last car i ever buy. But it makes me miserable to drive it. It's not fun anymore. Because of this stupid idle nonsense. I don't plan trips, i don't wash it, i don't take the top off anymore...

Argh. Help!

 

It sounds like you did not clean the throttle body??

Very easy to bill one for cleaning it and take a nap instead

Added air will cause a high idle but not effect the throttle body from closing

If the high idle can be stopped by moving the throttle pedal cable sticking or have we disconnected the cable and it still stays open??

I had the bracket break where the cable comes through the floor

TPS hanging up ??

Remember new parts can also fail !!!

 

Let's try and rule out the throttle cable. Why don't you try unhooking the throttle cable and then cranking it up and letting it warm up. Work the throttle linkage by hand and see if anything changes. The detail about tapping the gas pedal and it idling down again makes me think the cable has something to do with it. I suppose the butterfly in the throttle body could be slightly deformed causing it to stick when it gets hot. It very well could be something electrical or vacuum related but a mechanical issue is often easier to figure out when you don't have a lot of experience with the other.

If it's not mechanical, I might suspect an intermittent signal from the coolant temp sensor or one of the other sensors that will cause the engine to run in open loop without a constant signal to the ecm. If you had a bad wire or connection from any of them then engine would go back to open loop until it gets if's proper feedback from the sensor. The open loop condition will give you a high idle like it does while the engine is warming up. I can't remember if the TPS is one of these sensors or not. If it is, that could explain why tapping the gas would temporarily resolve the issue. There is a test procedure for the TPS in the FSM that is fairly easy to follow on the 3VZE. The book will make it look harder than it actually is but you can do it.

 

a sticky idle problem shouldn't cause such an extreme reaction... is this really about the truck, or is it more about life in general?

reading between the lines, it sounds like you don't work on the truck yourself, which is going to make things very frustrating... you need to be able to do simple things like confirm the throttle plate behavior when the cable is disconnected.

you can also try increasing the amount of slack in the cable, by adjusting the nut on the sheath.

 

you can also try increasing the amount of slack in the cable, by adjusting the nut on the sheath.[/QUOTE]

That's what I was thinking as well after looking at mine. Add a little free play to the throttle pedal. Removing the cable should give you an idea as to whether or not adjusting the cable length will work. I went out and pushed on my gas pedal with one finger and I do have just a little free play in it.

 

1. There is slack in the cable when the problem is occurring.
2. I appreciate the nickel-psychoanalysis. But the reason for the extreme response is its not a new occurrence, but a problem I've been trying to resolve for YEARS and no one can figure it out, me included. And I'm not a tech. Or even a wrench. I'm just a common sense guy so this has me baffled. So on some days my patience for it is nil.

But tonight, driving it for an hour, it ran perfectly. No issues at all. I left the radio off and just listened to my newly quieted truck (added a resonator to kill some exhaust drone) and every light it came down to correct rpm. Mind blown.

So idk what is what right now. But i appreciate the input on what else to troubleshoot. Pedal Freeplay adjustment is something im not 100% sure is correct so I'll double check it just to be thorough.

But because of the intermittency of the condition, its hard to pinpoint one mechanical cause.

It drove nicely tonight, first time in a long while. I'm pretty happy with that right now.

 

Glad it's working good again. I don't know if there is any spec or adjustment procedure for the free play in the gas pedal linkage so don't spend too much time looking at that. I was really just letting you know what my pedal felt like for comparison. If it does it again, you might take a look at your vacuum switching valves. They send signals to the engine to idle up in certain situations in order to keep the engine from stalling. You can unplug them and they will not function. If you unplug one of them and the problem goes away, that might narrow down your search. If you had a slight vacuum leak at one of them, tapping on the gas would probably stop it from idling up the engine.

 

So today was interesting.

I drove it about a half hour, ran perfectly. Then it started acting up: idle starts sticking at 1100, then 1200, then 1400...a pedal tap clears it as usual.

So i stop and open the hood, and I'm making the throttle stick by hand, gently opening it. It looks like it's the dashpot impeding it, but i know the part is new. So, i remove the throttle cable.

I can't duplicate the condition with the cable off. The dashpot slows it as designed, then the throttle closes completely every time.

But there's no bind to this cable. Sliding back n forth from either end, it glides with no snagging.

So i take the return spring off, and feed the twists in two rotations on the bottom, then reclip it to the top. This shortened the spring by about 1/4".

It's pulling the throttle shut Everytime and idling exactly where i set it at 850.
All day since, Everytime. I'm amazed.

Now, only unwanted symptom is low idle when cold, i think to be expected with the coolant bypassed from the Air Valve directly below the TB. I thought that valve idled it up on cold conditions only but I'm not certain of its function.

Either way, high idle mystery seems to be gone. I'm still in shock. Like is this finally over? No more tapping the gas every time i let off? Well i sure as heck hope so. Time will tell.

Here's a pic of what i did: Spring, shortened

you may see the bottom rings kinda bent from the first time i tried this and it didn't help. That was so long ago i don't even know. Years! But it's the missing piece of the puzzle today so I'm calling this fixed for now. Oohrah!

 

Glad you got it handled. Good thinking. I could tell you were fed up with it. You might think about buying you a new spring. Twenty five years of hot and cold can make springs loose their bounce. That's why they sell them. That and their tendency to fly over your shoulder into the weeds when you unhook them.

 

that spring is not stock, but if it works, do it!

you have the old slanted down intake plenum system, i thought that toyota went to the straight intake plenum by '88.

what you need to do is this, it'll make your cold starting much better: http://siestaoffroad.com/tbody.html

 

thanks for this link! i may do it someday, but not now, now that its running ok i'll leave it alone and hope to never touch it again.

besides, fancy red powder coat = faster! lol

 

I went thru your thread and did not see where you tried burping the system. Raise the front end as high as possible and let it idle and cycle the thermostat 3 or 4 times to get the air out of the cooling system. Leave the radiator cap off while doing this. This will cause some surging as well. Hopefully you got it fixed.