Idle issues

[mustangmax]

I've seen some posts similar to this before, but if anyone has any helpful info on how to fix this problem I'd really appreciate it.
Here goes:
My idle used to shoot up to around 2-2500k once it warmed up a little. With the engine running I disconnected the IAB electrical plug and the problem corrected ended. I replaced the IAB solenoid and valve, problem still there. I then replaced the EGR valve and sensor, no help. I cleared the codes and everything seemed to be ok for a while. Now the problem is back. It doesn't idle as high, but hangs around 1500. If I turn the key off then back on quickly the idle resets and doesnt cause any more problems until the next time I shut the car down completely and re-start it. Any words of wisdom?

 

[shttygtstang]

heard of people drilling small holes in there tb .dont know y had to do with idle though

DONT DO THIS THOUGH TILL SOME ONE ELSE SAYS TO

 

[mustangmax]

Yeah, Ive heard of that for a whistling or surging idle. Mine just shoots up and stays unless I cycle the ignition off then on again.

 

[shttygtstang]

whats your tb voltage .hows you iac that would control your idel air control goos sensor to start emaybe ones not working right and you ecu is compasating for it.clean um with brake cleaner see if that helps NO CARGb CLEANER IT WILL SCREW THAT SENSORS UP .give that a try hope i helped some

 

[mustangmax]

The last time I checked the tps it was right where it was supposed to be... I haven't checked it in a while. I have already taken off the tb, and idle air bypass and cleaned them all out with throttle body solvent. I'm stumped...

 

[90mustangGT]

Did you clean out the passeges to the IAC? Check for vaccume leaks? Did you try adjusting the throttle screw? Check to see if the throttle cable and cruise controll cable are moving freely and arn't bound on anything under the hood?

 

[shttygtstang]

i dont see any thing being kinked because it would jump to 1500 right way and it dosent dunno sorry

 

[shttygtstang]

vacume leaks tryu that you ecu is compasting for somthing

 

[mustangmax]

The throttle cable is new and I havent had any problems with cruise control. The idle is fine after I cycle the ignition, and it doesnt "search" like some of the vacuum problems cause.

 

[Silver85TC]

What codes did you get? When you "cleared the codes", did you correct the problems that the codes were showing? Did you disconnect the battery for a minimum of 5 minutes after replacing the IAB valve?

When was the last time you cleaned your MAF sensor? A dirty sensor will cause idle problems.

How old are your ECT/ACT sensor's? If either of those sensor's are faulty, they could cause idle problems. And no, you might not get a CEL if either of those sensor's are going south.

Lastly, how fresh is your tuneup? Plugs, wires, cap, rotor etc.? You should also recheck your TPS.

A buddy of mine bought an 86 stang that burned oil like a SOB and had the exact same idle problems you described. We did all of the things I just mentioned above, and the car idled like a new car. No more hanging idle etc.etc. Still burned oil like a bastard though!

 

[Rerun]

You say you got a new IAC valve? If so, where'd ya get it and what brand is it. Important answer may follow your response...

 

[eagle87]

The thing that bothers me is after you shut it off and turn it back on it fixes itself. What resets to make it better. If you fix this one your gonna make alot of people happy. If you have a good act,ect o2 iab clean maf and tune up good grounds maybe something in the computer ???? keep posting and good luck......

 

[shttygtstang]

look through you haynes manual it will tell you abought wire resistance and what to look for time to get dirty and start poking wires with your volt/ohms meter

 

[topdri]

Wow - I am having the exact same problems. I have replaced the TPS (Ford), IAC (Ford), and a MAF (75mm aftermarket - calibrated for my stock fuel injectors). I replaced the MAF because my mechanic got a code of low MAF sensor or something like that - no other codes showed up AND my check engine light never came on. What do you mean by "clear the codes?" Unplugging the battery clears the codes right? I have unplugged the negative battery cable several times after the above installs. The problem will go away then all of a sudden pop back up with idle surges as high as 2500 RPM. When I shut the car off, everything appears to reset for a bit. I did a tune-up about 8k ago with plugs, rotor, cap, fuel filter, oil, oil filter, pcv valve, pcv valve busing, etc. - ya know - the basic stuff. BUT I did not change the wires as they are only 23k old and look to be in good shape. I am all ears for a fix for this problem as it can be dangerous when you let your foot off the gas and the car keeps going.

 

[eagle87]

Something wierd. For a few days it cleared itself, after I noticed this I checked for codes I did it with the jumper wire. Got a code 32 that I always get, as soon as I removed the jumper wire started the car it started again. WTF go figure. I will figure this out it may take years but I'm going to.

 

[gungfusemaj]

oKAY LADIES DID YOU DO ANY mANIFOLD WORK ? eVEN IF YOU DID NOT i CHASED THE SAME PROBLEM FOR 2 WEEKS I BOUGHT ALL NEW CRAP, IAC MOTOR SENSORS THE WHOLE 9 YARD FINALY I BOUGHT A 20 DOLLAR PART FROM FORD THAT GOES IN IN BETWEEN YOU IAC MOTOR THAT WAS GUARENTEED TO WORK. STILL NOTHING.

BEING UPSET I WAS LEANING ON MY UPPER MANIFOLD AND MY CAR STARTING IDLEING CORRECTLY....I COULD NOT BELIEVE IT I HAD ALL NEW VACUME HOSE ETC....IT WAS 2 LOOSE BOLTS ON THE BACK OF THE UPPER MANIFOLD....I DONT MEAN FINGER LOOSE THEY JUST NEEDED TO BE TORQUED DOWN A LITTLE. TIGHTEN THEM DOWN AND THE CAR RAN PERFECT......JUST A SUGGETION


I AM THE BIGHAM AND I APPROVE THIS MESSAGE

 

[Stang8URMPRT]

Mustangmax.... One thing that might be causing or atleast not helping your problem is the fact that you have an overly large throttle body for your application. 70MM is way to large for your setup. I say slap your stock throttle body on, set the tps, and see if it clears the problem.

Nick

 

[aete2]

HMMMM im in the same boat and have done all of the above and to top it off this year it the odd time stalls now? Ford has had it i have looked and this is ticken me off ill be watching this thread!

 

[BlueThunder1988]

I'm having the same problem right now--occasisonal hanging/high idle just after warm up that goes away with a simple off/restart of the key... I'll have to check the upper/lower manifold... anyone else?

 

[GoldenEye]

I had very simmiliar problems which gradually got worse. Turned out to be a wiring short behind the intake in an near the 2 10 pin connectors. I would check your connections there witha meter and see if you have juice to everything. My idle would surge up and down, and worse when warm. car now has the most awesome idle now that everything is fixed.