idling rough at warm up

[eleanor'03]

My buddies 5.0 is having idiling problems. He has a '88 GT. He says when it's cold it's fine but once the car warms up the idling jumps from apprx. 750 to 1400, back and forth. Any ideas to help him out? I thought maybe the injectors need to be cleaned but that is a really rough idle. Thanks guys.

 

[86bluecobra]

sounds like TPS problems or perhaps IC sensor needs to be cleaned.

 

[bill302]

click on link below and click on solving idle problems 1-5 in link and perform these steps. good info.unless you have a speed density stang as hissin50 states below i edited in case you don't pass this point.

http://www.muscularmustangs.com/maintain.php

 

[HISSIN50]

If your friend has a SD stang, I would not follow the idle setting procedure above.

Have him pull codes, clean the IAC, check TPS, check his vac signal (critical for a SD car), etc.

My two cents. Good luck.

 

[Black1987Stang]

and pull the codes, maybe the maf for a suggestion too

 

[vristang]

I may be mistaken but...
Doesn't the computer ignore the signal from the O2s until they get warm?
Just another possible thing to check out.

Pulling the codes is the first thing to do.

jason

 

[eleanor'03]

Won't the codes come up only if they're showing an error? Another newbie question "What's an SD stang?" and "What is the TPS?" Thanks for bearing with me.

 

[bill302]

sometimes sometimes not, sd is speed density and tps is throttle position sensor.read link below it will explain speed density and efi massflo. 88 california models and 89 model stangs on up has the efi massflo system and 86 - 88 model stangs have the speed density system and 85 on down carburetors.see link since i really confused you. lol. also some people convert speed density to efi massflo.

http://carcraft.com/techarticles/24549/

 

[HISSIN50]

It can take 30-120 seconds for the lambdas to light off. Until then, as Jason said, their input is ignored.

The idle setting procedure is a bit different for a SD stang.

Codes can be stored without triggering the CEL. That is why when issues arise, even if the CEL is not on, it is wise to check for any stored codes.

Good luck.

 

[troyGT03]

Won't the codes come up only if they're showing an error? Another newbie question "What's an SD stang?" and "What is the TPS?" Thanks for bearing with me.

a speed density car doesnt really have a check engine light. you can see where it is in the dash but there is not a bulb or even wiring to that light. pull codes http://www.troublecodes.net/Ford/ and then work from there. unless it is a gt then the light works. lx=no check engine light

 

[troyGT03]

oops ...you have a gt. cel light should work. run codes anyway.

 

[HISSIN50]

SD cars dont have functional CEL's period.

 

[jrichker]

See the sticky "Help me create the Surging Idle Checklist" at the top of the forum for help with your idle problems. The first post in the sticky has almost all the details you need.

 

[gcwh02]

try and clean out the IAC