Last night I was out racing and I lined up with an '03 Cobra. I sprayed nitrous that race and when I pulled back in and parked my car it was idiling extremely rough. It almost was acting like it was going to die but it never would. After letting it sit for awhile it finally threw a service engine soon light on. I was just curious if anyone had any suggestions of a place to start looking. I still have regular oil pressure for a stock ls1, and I dont think i am burning any oil or anything like that because my car isn't smoking. If you have any suggestions or have had a similar problem please let me know. Thanks.

 

Check your spark plugs. You may have burned a tip. That caused mine to idle rough and when I was driving down the road the SES light was flashing. I changed the plugs, reset the computer, and the problem was gone.

 

Did you win the race? Please say "yes."

 

Hell Yeah I did!!! We ran 'em up to 120 from a dig and I had him by a little more than 3 Car Lengths.

 

I'm sure you already did this, but which code did you throw?

 

At least you won.

 

 

probably a P0300 muticyliner missfire or any one of the missfire codes P0301 through P0308

 

It threw a misfire code on #7. The plug was straight gone. I replaced the plug and put it back on the code reader and it still said misfire on #7. I pulled the plug back out and it had some fuel on it. One of my friends suggested that we put air in the cylinder and listen for a leak. I am hoping that It is a burnt valve. I was kinda thinking that since parts of the spark plug obviously were missing it might be stuck to the back of a valve. Oh yea and we popped the drivers side valve cover off and disconnected the fuel pump relay and watched it while we turned the motor and it isn't a bent pushrod or anything like that. So im pretty sure that its one of my valves. Like I said there is no smoke coming out the exhaust and the dipstick stays where it should be, and i can pull off the oil cap and push my hand down on it and I dont feel pressure. Like I said if anyone has any suggestions just go ahead and let me know what you think.

 

Did you by any chance over rev on that run, as I have bent valves this way (if in fact it's a bent valve) and ran about the same as you describe. Also, #7 is one of the cly that can give problems on the spray (read: distribution). A cly leak down test will pin point a bent valve/piston seal issue. If you don't know how to do it, myself or someone else can walk you through it, as it's really quite easy.
Robert

 

When you say the plug was gone...Do you mean broke off or burned off gone?
Big difference....

 

Burnt off