So, here's the problem I'm having. My car is idling rough, particularly after it gets warmed up, but not exclusively after it gets warmed up. I have Pacesetter LT's, a lid, cat back, etc. An acquaintance tuned my pcm on LS1edit years ago and it ran fine for thousands of miles during that time, now this problem. So I pulled the codes, got the AIR, EGR cuz those are deleted on my car, but it also threw a bad O2 code, so I changed those. It ran fine on the way home but as soon as I got to my house it was running rough again. Haven't pulled the codes again cause I don't have my own scan tool. I have heard maybe something with the fueling system or maybe the tune itself. But could it be the tune after this long? Any advice would be appreciated.

 

Could be a lot of things, but my first suspicion would be an exhaust leak - causes the O2 sensor to think it is lean and add unneeded fuel. This would happen when it is warmed up and in closed loop. You need to get someone to scan it for you and see what is up...

 

Pull the codes again? What if it's the o2s again, with new o2s on there?

 

Like blk said, if the code for o2 is heater than look at electronics. If the code is mixture than look at live data to be sure when blip throttle it response. That shows most likely the o2 and wiring are functional. If hanging lean, be very sure no exhaust leak.

 

Also, could be a lot of other things but first suspicion.

 

When I said scan, I meant log data to see what it is doing... not just pull codes.

 

I'm pretty sure I don't have an exhaust leak. I could be wrong, but that's not my first suspicion. So, could it be that after all these miles I was running on a not-so-good tune and it's catching up to me?