95 Gt With Problems

[mustangcrazy]

I hope you can help me. My daughter drives an 95 mustang gt, stock, 5sp, with 122,000 miles on it. The problem is...the check engine light is on but no codes can be read. When the light comes on the rpm's are over the place and it will eventually stop running if it is idling. I have had it to three different people here in the town we live in and the one guy is suppose to know everything there is to know about mustangs and he can't find the problem. He has checked the vacuum and it is fine, we have installed new plugs, plug wires, pick up rotor, pcv valve, and ignition module.

Can you give me any help as to what is going on with this car and what they need to be looking for.

Thanks

[shibby]

Check the idle air control valve, those are symtoms of a bad one. Also, at what specific, if any, driving conditions does it do this? Low rpm, light throttle or heavy acceleration, idle only, etc. That will also help me rule out some things. Let me know.

[mustangcrazy]

It does it intermittenly, but most times when it is idling. If the light comes on when you are driving you do not notice a change in preformance and if you keep driving the light will go off. But when the car is idling it will actually die if you do not keep giving it some gas.

[shibby]

Locate the EGR valve and pull the the vaccum line off. This will keep the the valve from recirculating exhaust gas back in to the intake, then go drive it, focusing on 2,000 rpm shifts and smooth, gradual acceleration through the gears and see if it stops. Doing this will most likely make the check engine light come on but you can reset that by disconnecting the negative battery cable, (and no that is not the proper way to reset a code, but if you don't have a scan tool then you have no choice.) If it stops then you need to check your spark plugs and see if they have an abnormal discoloration like an red,blue, or greenish haze on the tip. This can be caused by using certain fuel additives like octane booster or by using too low of an octane gas like 87 instead of 93. The funk on the plugs not allowing a fire strong enough to combust the recirculated mixture, but strong enough to burn a cleaner mixture. If none of this is the case then I would replace the idle air control valve they don't do so well with 122k on them. The throttle position sensor and the egr position sensor are also probable but I'm leaning toward the IAC valve. Keep me posted.
Almost forgot, If your plugs do have the funk, replace them and use premium octane fuel and do not use any octane booster or any particular fuel additive that you may have been overdosing the car with to try and fix the problem and it should go away almost immediately.

[mustangcrazy]

Thanks for your help. I will get someone to do that this weekend and will let you know what happens.

This is my daughter's baby and she does not like it when it does not run.

[shibby]

Anytime.:cool: