idle and stall problems on '92

** I have a '92 LX 5.0 with 215,000 miles.

With that many miles on it, I'd start with a compression check. If that looks okay, I'd then check fuel delivery and IAC operation.

Incidentally, congrats on getting that far. My Winter Beater just turned over

183,000 miles, and still runs like new. It gets a tune-up and a new fuel injector this weekend (old one is OEM TBI and leaks a bit) and it looks like HELL, but runs like the devil. I can only hope my GT runs that strong when it gets that old.

Regards,

-JD

--------------------------------- JD's Locally-Famous Mustang Page: http:/207.13.104.8/users/jdadams---------------------------------

41 and 91 would apply to your car. That is a lean condition from your O2 sensors. If you have never replaced them, it would more than likely clear up those 2 codes. But........this could also be caused by a bad ground wire. The HEGO (O2) ground on your car is an orange wire that comes out of the injector wiring harness and connects to one of the bolts on the rear of the lower intake. It could also be because of a vacuum leak. Some folks have ways to find vacuum leaks on hoses while the car is running but none have ever worked for me. Too impatient I guess. I always examined every hose closely by taking it off.

When you replaced the EGR valve, did you also replace the EVP (the sensor attached to the EGR valve)?

In addition to the items listed above, a fuel filter could cause a rough idle like you are describing but one quick and cheap thing to try is to clean the idle air bypass valve on the throttle body. Take it off the car, separate the two pieces and spray it out really well with some carb cleaner.

Casey

Here's a list of things I would do to try and clear up the problem:

1) Remove the throttle body, EGR plate and ISC valve and clean them thoroughly. Reinstall them with new gaskets and see if this helps.

2) If the above doesn't work the ISC valve might be bad. Replacing it may be necessary.

3) Check the O2 ground and clean the wiring harness connectors near the O2 sensors and apply dielectric grease. They can get very dirty and oily which can effect the signals sent to the computer. They make need replaced. Especially if they are the original sensors.

3) Clean the MAF element gently with brake cleaner and a Q-Tip. A dirty MAF element can cause pinging and other issues that may effect idle.

4) Check for vacuum leaks. The easiest way I have found to do this is to spray starting fluid in areas where a leak might occur. When you spray on or near a leak the engine idle will increase in direct proportion the the size of the leak.

Thanks for the reply.

From looking at things again, I see I replaced the sensor part of the EGR valve. Maybe the valve is what is messed up. As must be obvious, I don't understand this very well.

I'll check the codes again tomorrow and clean up the idle air bypass.

Thanks again, Bud

Wow, thanks for the suggestions! Now that I've spent the last hour reviewing my service manual and the web figuring out all the stuff you guys have mentioned, I have a plan of attack for tomorrow.

One (stupid) question - does a '92 have an ISC valve? I assume that stands for idle speed control valve, but can't seem to find any mention in my manual. I found the idle air bypass valve. Is that related?

The bonehead thanks you guys

Bud

It's the same thing. The ISC/IAB is located on the side af the throttle body.