1988 Grand Prix Idoling problems

[ksuwildcatz]

My grand prix will just die after it starts. I will list everything that has been replaced since i brought it into the dealership who said it was the EGR and replaced it. After they did this it ran well for 1 month then back to dieing. I replaced the EGR myself using the warranty it ran for a day. I changed the idol air control - no change in performance. I changed the PCV - no change in performance. I changed the MAF and it ran for 3 miles then died and again won't stay started. Does anyone have any ideas? This car was my wife’s first car since 95. She bought it when there was 68k on it. We now have 275k on it with the original engine and trans. I really want to get 300k on it but i am about to give up. Thanks for any input on this issue.

[ksuwildcatz]

I also replaced the O2 sensor. Could replacing the MAP sensor do anything for this?? or how about the ignition module? If anyone thinks it could be the ignition module could you guide me through taking it off. Thanks

[maxwedge]

If you keep replacing everything I guess at some point it would be fixed. When it dies do you have spark, injector pulse and pressure at the rail, these are all basic diagnostic steps.

[ksuwildcatz]

I just replaced the map sensor and it went from not running at all to me being able to drive around 1/2 mile. It sounded good but every once in a while i would lose all power and the rpms would go down to 1. Then it would jump right back to where the rpm was at 3.5. Then it died after 1/2 mile. It started right back up but it didn't run as nice as it did before.

To answer your question I would believe i have spark, injector pulse and pressure at the rail because I was able to drive but I am just a math teacher so I am probably wrong. I hear the injector pulse when I turn the key as for the pressure and spark I am not sure how to check. Thanks for your responses

[ericn1300]

if each time you change out the egr and it runs good for awhile, you may have a problem with carbon particles breaking loose in the engine and blocking the egr. when replacing the egr did you notice if the gasket had a screen across the opening to catch the larger carbon particles? You can get screened gaskets at the NAPA auto parts stores. You can try cleaning the egr by blowing it out with compresed air. don't use any chemicals, they might cause the pintel to stick causing the same problem.

to reduce carbon build up in the engine use a good brand of gas with cleaning additatives and drive it fast and hard. city driving and short trips makes the problem worse. i swear by chevron gas. my wifes car was hard starting, stalling when cold and running rough when cold. a couple of tanks of chevron and it was running fine again.

[richtazz]

you need to check fuel pressure at the rail. I would guess that you have a fuel pressure regulator and/or fuel pump going bad, that's why it will run for a short period and then die. Also check the underhood vacuum lines going to the MAP and regulator for cracks or leaks, as that will cause all kinds of headaches. IF there is gas in the vacuum hose at the regulator, the regulator is bad.

[ksuwildcatz]

How difficult would it be to change out the regulator and/or fuel pump besides the cost? Pictures are very helpful if it can be done. I am just a stupid young math teacher who can't afford to take it in to a shop. Thanks

[richtazz]

The fuel pressure regulator is fairly simple, buy a repair manual for your car and follow the proceedure. The fuel pump is a much bigger project, as it is in the tank.

[ericn1300]

autozone.com has most of the repair manuals on line now. i wasted my money buying one

[auxbar]

I think richtazz nailed it. I used to have an 89 GP and at about 150,000 mine did the same thing. Mine was the fuel pump.

[ksuwildcatz]

Well I replaced everything that people thought of here on the forum but it was unsuccessful. I ended up taking it in to the local pontiac dealer. I had 3 injectors that were bad. After replacing those it runs like new again. Thank you for all your help on here.