Car stutters and breaks up after 15 mins of running (closed loop I guess)

[Berman]

Boy it's one stupid problem after another for me. The 1st 15 minutes the car is on it runs fine, you can go full throttle it hauls ass, etc. As soon as the car warms up more it has totaly random sputters and breaking up. Sometimes when it goes into boost. Sometimes when it boosts past 10psi. Hell sometimes when pulling away from a stoplight.

Listen to how I find out about the problem. I pull up at a light and who do I see next to me but a 5.0. He revs it, obviously wanting to play. I spool it up on the brake, and right when I launch when the light turns green .... sputter sputter fart splat. (feels like ignition breaking up). So I should go check on the corral for a post "killed a white GN last night"

Any suggestions? o2 sensor? maf?

 

[John Larkin]

I would think the O2 also on the front end, but I'm not a chip guru. I'm not sure what closed loop reads, but I'm guessing the O2 sensor. Do you use anti-seize on the O2 sensor threads? If so, that's been known to cause grounding problems. However, n20junkie replaced a crank sensor a few months ago and it cured a stumbling problem he had. I read that on a search anyhow.

 

[Berman]

tttttttttttttttttttttttttttttttttttttttttttttttttt

argh.

 

[blackshoebox]

Originally posted by Berman

Any suggestions? o2 sensor? maf?

Do you have any type of scan tool?? I would change the o2 sensor if it is old and has had leaded race gas run through it. If that doesn't work check the maf, and then coil if you still have problems. If you have a scanmaster or some type of scan tool the diagnoses of the problem should be cake.

Alex

 

[Joe 1320]

Sometimes a coilpack/module runs fine until it gets enough heat in it... then it goes south.

 

[blackshoebox]

Originally posted by Joe 1320
Sometimes a coilpack/module runs fine until it gets enough heat in it... then it goes south.

If the maf and o2 sensor checked ok, this would be my next thing to check also.

 

[blackbuick87]

Berman if it helps you any I just changed my O2 sensor after having the exact same symptoms and went out and beat the piss out of my car and it is running good now. I am keeping my fingers crossed because I have had false hope in the last couple weeks but i ran to 20psi 10 times (almost got a ticket) and it did not pop once.

 

[Berman]

I'm frustrated now. So far I have changed: ecu, chip, crank sensor, o2 sensor, coil pack, ignition module and the problem is still there.

Any other ideas?

 

[86underboost]

02 sensor or the ign module....check em both. what do the 02s look like at idle? do they bounce around or stay in one place...they should move around. you could also look at the cross counts...they should increase pretty rapidly from 0 to 255 then start all over again.