96 lumina, heres a strange one!

okay, 9 times out of 10 my lumina fires right up and runs great. However, sometimes, when I drive somewhere and shut the car off for a little while, when I go to start it again it sputters and stalls and backfires a little bit and wont stay runnin, or if I try to drive I can put the pedal to the floor and the car bogs out and eventually stalls. Heres the funny part, if I let the car sit for about an hour it will fire right up! A couple of things I notice when it wont start are the check engine light comes on, and it smells like its "running rich". Any help would be greatly appreciated, alot of you know how stressfull and unsafe an unreliable car can be, especially with kids in the car.

oh yeah, the "service engine light" turns off after I let it sit and it starts!

Run to advance or autozone and have them pull the code that's setting off the check engine light. usually its free and it'll get you closer to what your problem is.

The service engine light turns off when I get it started, the guy at AutoZone said its gotta be on for him to check it. I asked him if the code would be stored and he said no, in a tone that made me feel like an idiot.

I thought they were stored myself. I dont know. Sounds to me like a bad ground, or bad connection somewhere. Check all wiring.

Mine does the sputter and die or rock back and backfire sometimes, but doesn't try to run like that, and always starts right up on the next try. It was explained at one time as having to do with the way the ECM references crank position via the crank sensor. Sometimes in certain circumstances the ECM will "loose count" of the teeth that trigger the crank sensor, causing ignition timing to be incorrect. The result is a rough idle or no idle, followed by that "huff" through the intake as it dies. It should, on the next try run fine, no? I have reduced the occurance of this by always waiting until I hear the fuel pump stop before cranking the motor on FI cars. Give the ECM time to look at all the variables and react before the motor is cranked. I know, you shouldn't have to do that, but they start easier if you do. Just turn the key to "on" and wait 1-2-3 then crank, and see if it still does it. If it does, I'm betting the crank sensor or spark module is going out. Replace both, and maybe a fuel filter, and it will probably be fine.

your exactly right about turning the key forward and waiting for the fuel pump to stop running before I start it. I do that everytime and it fires right up on the second or third try. However, my problem is when it doesn't start or wont stay running or rev up when i depress the gas pedal(when the motors hot). I could turn the ignition a hundred times and it wont start unless I let it sit for an hour or longer.

I wanna be sure before I spend money on new sensors, that I change the bad ones.

thanks

your exactly right about turning the key forward and waiting for the fuel pump to stop running before I start it. I do that everytime and it fires right up on the second or third try. However, my problem is when it doesn't start or wont stay running or rev up when i depress the gas pedal(when the motors hot). I could turn the ignition a hundred times and it wont start unless I let it sit for an hour or longer.

I wanna be sure before I spend money on new sensors, that I change the bad ones.

thanks

How many miles on this one? Crank sensors and ignition modules are both the common cause of these symptoms, particularly the "heat soak" no-start you describe is more like a module. Both have similar service life, so replacing them at the same time can keep you from duplicating the problem in the near future. I don't know if AutoZone can test the ignition module, but unless it was at the temp that it cuts out at, it would test fine anyway. The module lays under the ignition coils on top of the motor, with the coils mounted to the top of it. It's easy to replace, I think if you can do it yourself, it would be worth the gamble. Chances are if it has more than 75,000 miles on it, it's gonna go out soon anyway.

We'll I think I'm gonna take apart the ignition system assembly and do some tests. After reading your last post I checked out the AutoZone site and they got a pretty detailed section on how to check the ignition system. It looks pretty complicated though. Should I just replace the coil & module? or is it worth testing? the car has 150,000 miles on it and i've brought it back to life a couple times (wiith alot of help). Could you offer anymore suggestions with this procedure?

thanks again

Codes are stored until they are cleared. Maybe the autozone guy's computer is different, but I can pull a code off my car that's over a year old without any problem.

We'll I think I'm gonna take apart the ignition system assembly and do some tests. After reading your last post I checked out the AutoZone site and they got a pretty detailed section on how to check the ignition system. It looks pretty complicated though. Should I just replace the coil & module? or is it worth testing? the car has 150,000 miles on it and i've brought it back to life a couple times (wiith alot of help). Could you offer anymore suggestions with this procedure?

thanks again

There is three dual-tower coils, each firing 2 cylinders. They plug directly into and sit on the module. If a coil goes bad on these, it is very distinct, because two cylinders are cutting out simultaneously, a very hard misfire. Your problem sounds like weak or erratic spark, something that the ignition module can do when bad. I think your coil packs are O.K. Unfortunately, I have no specific test for this, other than I carry one good spark plug in my car, and if it dies, I pull off 1 plug wire, insert the good plug and ground it on the motor. Have someone crank it and see what you get. A bad module usually produces a very short, weak, yellow spark, if any at all. A good one will throw a healthy, fat, blue-white arc in the gap, with a nice snap sound, rather than a weak tick. It might be interesting to try tapping on the module while someone cranks the motor when it won't start. If it starts or fires sporadically while you do that, you know what you gotta do. Make sure your crank sensor is plugged in securely, and the wires to it aren't sagging into something when it gets warmed up.

The service engine light turns off when I get it started, the guy at AutoZone said its gotta be on for him to check it. I asked him if the code would be stored and he said no, in a tone that made me feel like an idiot. Thats bull, any code that stays on for more than a few secnds will be stored in the ECM until you clear it.

I GOTTA CODE FOR THE "Mass Air Flow (MAF) Sensor" COULD THIS BE WHAT IS CAUSING MY PROBLEMS?

KOOTERSTANK was right the code was stored!

Hey JEFFCOSLACKER what do you think about the MAF?
its $109.00 at NAPA.

Some of the people who work at autozone are morons. :banghead: The codes are saved until you clear them. I think for some of the people who work there, it's just a paycheck, being good doesn't mean anything to them.

Here is a link so you can check your module/coilpacks:

http://members.fortunecity.com/slade901/automobile/Ignition_Troubleshooting.htm