Engine wont run after 10 minutes of driving

[Brendon444]

94 z28 lt1


Got my engine back in my car and it ran good for about 30 minutes then started missing and sputtering and just wouldnt start. Took out the opti spark and it seemed wore out so replaced that thinking it was the problem. Started it up and it ran fine for 20 mins then started missing n sputtering n wouldnt start just like it did before.

THe computer said it was the maf changed that n it ran good for about 15 mins then started sputtering and quit again.
Any ideas what would cause it to run bad after 15 minutes.

[4onFloor]

02 sensor maybe? reason being is because the engine doesn't use the O2 sensor until it's up to operating temperature

[Brendon444]

its like after i drive it fer 10 mins something makes the timing go off and it starts missing n sputter n dies.

[y2icon]

i said o2 sensor might not be getting enough air/fuel mix.

mine was messed up on my century did almost the exact same thing

[89IROC&RS]

O2 sensor is a good guess and a no brainer to swap so starting there is always a good idea. from there it could be a cam sensor, knock sensor, or ignition coil perhaps?

[Brendon444]

Originally Posted by y2icon

i said o2 sensor might not be getting enough air/fuel mix.

mine was messed up on my century did almost the exact same thing

I don't believe this is the problem. The engine goes out of time after about 10 minutes and seems to be related to temperature. The engine is so out of time that the starter has a hard time turning it over. When the engine cools down, it starts fine for 10 minutes and then goes out of time.

Installed new comp cam, optispark, wires, plugs and switched the MAF sensor. Still the same conditions.

Could it be the ignition control Module (ICM) or the knock sensor or coil???

All help will be appreciated.

[Genopsyde]

Originally Posted by 89IROC&RS

O2 sensor is a good guess and a no brainer to swap so starting there is always a good idea. from there it could be a cam sensor, knock sensor, or ignition coil perhaps?

...

[4onFloor]

Originally Posted by Brendon444

I don't believe this is the problem. The engine goes out of time after about 10 minutes and seems to be related to temperature. The engine is so out of time that the starter has a hard time turning it over. When the engine cools down, it starts fine for 10 minutes and then goes out of time.

i'm not sure, but the O2 sensor may influence the timing and if it's bad it would cause a timing problem. and like I said before, the O2 sensor isn't used until the engine warms up and goes into closed loop operation.

the only other thing i can think of would be the IAT sensor. i know that it plays a big part in timing because that is what people bypass with these miracle resistors that supposedly give 20hp.

[Brendon444]

Found the problem so far. The ICM and coil needed to be replaced. I haven't picked it up yet, but the garage had it running for an hour and it worked fine