1991 Gt Foxbody Rough Idle/stalls

[ddrew01]

So my 91 GT has been having some idling issues lately. Whenever I start the car it either stalls straight away if I dont step on the gas right away, or the RPMs will just jump around and it will not stay steady, and the eventually stall out. This past summer I took it on a pretty far road trip ( From NY to VA and back ) and ever since then this problem has been happening. I have tried just about everything you can think of. I replaced the IAC, adjusted the TPS, cleaned the MAF, I even tried flushing the the fuel system and nothing works at all. Also when the car is idling the battery level meter in the car goes up and down as well... Maybe that is the problem? I really want to get this fixed ASAP so any help would be greatly appreciated.

 

[mikestang63]

run the codes

 

[RaggedGT]

So my 91 GT has been having some idling issues lately. Whenever I start the car it either stalls straight away if I dont step on the gas right away, or the RPMs will just jump around and it will not stay steady, and the eventually stall out. This past summer I took it on a pretty far road trip ( From NY to VA and back ) and ever since then this problem has been happening. I have tried just about everything you can think of. I replaced the IAC, adjusted the TPS, cleaned the MAF, I even tried flushing the the fuel system and nothing works at all. Also when the car is idling the battery level meter in the car goes up and down as well... Maybe that is the problem? I really want to get this fixed ASAP so any help would be greatly appreciated.

Here is a thread,with a TON of info in it.. Somewhat overwhelming-but all very useful and will help you with your problem...
Step 1.- Pull Codes
Step 2.-Go through this check list

http://www.stangnet.com/mustang-forums/threads/help-me-create-the-surging-idle-checklist.698148/

 

[General karthief]

Run the codes, do the check list, I would look for a vacuum leak, and the alt. gauge will fluctuate with rps

 

[ddrew01]

I also just installed a powered subwoofer. Could it be that the alternator is not powerful enough?

 

[Mustang5L5]

I also just installed a powered subwoofer. Could it be that the alternator is not powerful enough?

Doubtful. You can find out by just turning the radio off.


Step #1, run the codes and post them here.

 

[General karthief]

Run the codes, do the check list, I would look for a vacuum leak, and the alt. gauge will fluctuate with rps

rps? maybe rpms,
neeed. Moorre. Cofffffeee.

 

[sawdeanz]

I would listen to the smart people and follow the list but I would also mention the ignition system. I had similar issues that steadily grew worse and worse, with misfires and eventually an engine that would stall when I pressed the gas. Replacing the distributor solved the problem.

 

[stpete]

If you have underdrive pulleys, the stock alternator at idle doesn't put much out. Electric fans and high power stereo will cause problems.