I took my car to the track Friday and after the second run it started backfiring a bit, so I called it a day. (Mods listed in sig) I'm wondering what exactly could cause this? The opti, plugs, and wires are all only a year old. So I doubt ignition is the problem. It's not throwing any codes. I don't know if the O2 sensors have ever been changed, but if they were not functioning correctly wouldn't they throw a code? Any feedback would be appreciated, thanks guys.

 

Backfiring is unburned fuel hitting the exhaust. I would start with the igntion, even though you've convinced yourself it can't be the problem...

 

I don't know if it will help, but you might try a tune if you don't have one already. I have read posts about some exhaust popping going away afterwards. If nothing else it should run better anyways. MADZ28.com has a very fair price for their tunes. I felt as if Ion did me right. Bird is probably right, don't rule it out.

 

Well, the previous owner did all the engine mods and had it dyno tuned. I guess my question would be now, if it's not the 02 sensors, how can I test the opti? The plugs are brand new and the wires look good. I replaced my pushrods a couple months ago, but it ran fine right after that, so I'm also going to readjust my rockers just to be sure.