STRANGE IDLE PROBLEM

[STEALHORSE]

I have a strange idle problem that I need help with.
I have a basically stock 89 GT. When the motor is cold it cranks fine, but after the motor is warm and I start it up it runs crappy for about 2 minutes and then like someone flip a switch it idles and runs smooth. During the first few minutes of starting it surges from 500 to 1500 rpms and sometime dies. After it clears the motor runs fine no surging or dying. I did a tune-up less than 6 months ago (wires, plugs, rotor and cap, ect) , I have checked and cleaned the MAF, IAC, Throttle body, Pull codes nothing shows up, Reset the base idle, checked and set TPS, replaced o2 sensors less than a year ago and replaced the ECT two weeks ago. Checked for vacuum leaks. The EGR has been deleted along with all the other smog stuff few years ago. I have noticed that if I try to drive the car during these first few minutes of starting I do not have any brakes so I have to sit and let it run till it clears up. This just started a few weeks ago and other than the problem with start-up the car runs great. Any ideas would be greatly appreciated.

 

[liljoe07]

Posted via Mobile Device

Not one codes?

If the EGR and smog was deleted, you had a bunch of codes. Some in the KOEO ,a some in the KOER tests.

There is always a code, if only a systems pass code. 11

 

[hotrodredneck]

hope this can help

idle probs?...this may help - Military Mustang Forums

 

[STEALHORSE]

When I said no codes I meant no code that would pertains to this problem. I have run code multi times. Yes I got and 11 and I got codes on the EGR ect, ect but no codes that would explain why it would idle like this, Yes I ran the KOEO and KOER and also the cylinder balance test which it passed.

"idle probs?...this may help - Military Mustang Forums"

Yes I have followed this procedure or one similar to it and with no results to solving the problem (read original post)

I have checked fuel pressure, fuel pump, and relays and all was good. I think I have just about checked everything and nothing stands out as a source of this problem.
I have researched this on this form and others, but no matter what I have done it still will not idle after the engine is warm. There is something I'm missing?

 

[hotrodredneck]

could be your brake booster. the reason you have no brakes is there is no vacuum there for the booster to work. If you have already checked the rest of the normal fixes, then look into the brake booster.

 

[liljoe07]

Try and clean the 10 pin connectors behind the intake.

 

[STEALHORSE]

Try and clean the 10 pin connectors behind the intake.

I will try and clean them this weekend. But if it was the 10 pin connectors wouldn't it have a continuous problem. Like I stated before this problem is only when I'm cranking it after the motor is warm and then only for a few minutes then it runs fine.

 

[liljoe07]

Posted via Mobile Device

I'm going off your first post, and the idle problems. The 10 pins are notorious for intermittent problems. It may or may not work, but its free to do.

 

[9050lx]

No brakes sounds like a huge vacuum leak from a leaking brake booster,either that or it is too low rpms to idle.I changed my IAC recently and seemed to make a difference even in cruising performance up to about 1800 rpms.My guess is da booster, cap the vacuum line temporarily to diagnose.

 

[STEALHORSE]

No brakes sounds like a huge vacuum leak from a leaking brake booster,either that or it is too low rpms to idle.I changed my IAC recently and seemed to make a difference even in cruising performance up to about 1800 rpms.My guess is da booster, cap the vacuum line temporarily to diagnose.

Yeas I think it is just that it is idling so low that there is not enough vacuum. because I have fine brakes afterwards no leaks, Like I have stated before this only last the first few minutes of cranking and then the car runs fine. I think it has to do with start-up what sensors or whatever does the car read during the first few minutes of starting? Someone out there must have had the same problem are is mine unique?

 

[9050lx]

Mine did exactly the same things with the exception of the brake problem you described.Fixed after a new IAC.