So, I found that I have a rather complicated idle problem. Hope you guys have some input/ideas because I have no clue where to start. Here goes:

Truck is a 92 22re with supposedly 105k miles.

Whenever I take it on a 4 hour drive from school to my house, I always notice after finally getting off the interstate that when I roll up to a stoplight and press the brake, the idle starts to drop then go back up, surging every few seconds like crazy.

This went away the next day or so, but every time I've made that 4 hour drive, it happens for longer and longer each time.

Now its really bad, and on top of the idle surging while the brake pedal is pressed, it ALSO idles really really high when in neutral and even sometimes surges but in fewer intervals when in neutral.

So does anybody know what's up with this? I figure it might be a vacuum leak or something but I have very limited experience working on cars in general so I'm just really lost

 

If your idle is too high (i'm guessing 1300 rpm+) and you step on the brakes the ECU thinks your coasting to a stop and kills your injectors to save on fuel... While in nuetral it'll do the same thing surge, lower your idle and the surging will go away...

 

I wonder if thats what happens to my truck. Cause after i get off the freeway and go to netural my RPMs drop and sometimes my truck dies out and sometimes its able to save its self.

 

mine has been doing this for a year or so, i originally thought it was a vacuum leak, not so..I also checked my idle, its perfect, from what i've read it could be a number of other things..here is a good thread on it

http://www.yotatech.com/f116/famous-high-idle-surge-culprits-142472/

 

Hmm, I'll check my idle and lower it some.

And thanks Joey for the link to that thread, I'm checkin it out now.

Thanks guys.

 

let us know if you fix it, cuz i have not been able to find whats causing mine to do that..I thought a new engine would have cured it but nope still around...

mine only does it with the A/C on tho...how about yours?

 

I'm betting you both have a bad "cold air valve"...

Here's a simple test to find out if your cold air valve is bad/stuck....

1. Warm up the engine completely.
2. Remove the intake boot at the front of the TB (throttle body).
3. Duct tape the big hole shut on the lower right hand corner in front of the TB plate/butterfly. Please make sure you clean where your gonna tape so the tape doesn't get sucked in.
4. Connect the boot back.
5. Start up the engine. **do not REV!!

If the idle changes significantly, your cold air valve is bad.... R&R is necessary...

If the idle doesn't change at all, your cold air valve is still good and you need to adjust the idle speed screw and possibly the AC idle up screw aswell...

Good luck!

 

another posible problem and solution

It could also be a faulty brake booster. About two years ago the brake booster on my 85 was not fuctioning properly. the brakes got hard and the idling of the motor surged in the same way you described to the letter. When I replaced the booster the motor returned to idling normally. The easiest way to test to see if the booster is the problem is to unhook the vacum hose from the booster. If the motor idles better replace the brake booster. A brake booster for a toyota pickup can be hard to find but you can also use one from a comparable 4runner. The only issue I encountered is the new booster made the brakes overly powerful and touchy.

 

BYE you think thats my problem too?

 

I had the same issue and went through damn near everything before I figured out eventually it was the "cold air valve" or "idle air control valve." Its basically a reed style valve that lets air into the intake when its cold, and closes when the coolant running through it reaches a certain temperature. Its very similar to a thermostat, because of the nature of the part, I decided on a brand new one from the dealer.

 

Sweet thanks alot guys!

joeynational: mine does it without the A/C running, I don't have working A/C haha.

Upon checking idle adjustment screw, I did notice it was way out. I adjusted it down, about 3/4 of a turn from fully closed and the idle dropped back down significantly. Also, the surging has gone away. I feel stupid now because that seems to have completely fixed the problem! but the thing is, I know for a fact that I adjusted the idle down about a month ago, and I haven't touched it since, so I have no idea how it did that.

I do think that perhaps the IAC valve needs to be checked though, since it has done this repeatedly. Thanks for the how-to, B.Y.E.

 

im going to try this, but being mine only does it when the A/c is on do you think its just the AC idle? where is that adjustment done at?

 

AC idle up screw Is the large hex/flat head "plastic" screw on the top right hand side of the intake plenum when looking at the engine from the front...

 

so counterclockwise will lower the speed right? I couldnt find anything about it in my manual, do you know where or what the specs are for the AC idle speed?

 

Fully warmed engine idles @ 800-900 rpm. When the AC kicks on it should jump up to 1000-1100 rpm...

Yes, counterclockwise lowers the idle speed... It's basically an air bypass valve. So tightening closes the valve and vice versa to increase idle speed....

 

I had this exact problem and when I put on an intake and adjusted the air bypass valve to have it at lower rpms the problem totally dissapeared!

 

my truck did this to,if you get air in the cooling system it will have the exact same symptoms.

 

ya i had the same issue with mine and it happened to be the air valve,,,

 

Ok so my truck started surging again. it happened after i took a 6hr drive from davis to oxnard in cali and now when i start it it idles around 1000-1100 but when it warms up it goes up to 2000 rpms and surges evben when i press the brakes im almost certain its that cold air valve on the tb is there a diagram or a writeup that shows how to replace it?
Also the idle screw is turned all the way in the closed position and it still surges :/

 

If the idle valve is screwed all the way in check the throttle linkage. take the big hose off and make sure the throttle plate is closing completely. It could be that the cable is binding up, dash-pot is jammed, stop is out of place, etc. Also check your coolant, if you have an air-bubble that gets caught in the aux air valve coolant passage it will not function correctly.