For 2 years now I had the same tune and same mods. LS6 intake, C2 cam (.224/.224 .581/.581 110 lsa), 5.3 Stage 2 heads, 3200 stall, rock-on 4l60e tranny, 3.73 gears, factory injectors, racetronix fuel pump, LT headers, no cats or mufflers. Recently, I took my car to a tuner to get it fine tuned for streetability. Nothing major. Just reassurance the car runs as perfect as possible. During our venture/driving around for the tune, my passenger rear tire blows out. We put the spare on and we both noticed the car begins to surge immediately after changing out to the spare tire. I trailer the car back home and put on new tires. The car still surges at low rpms and sometimes backfires. I have owned this car since new and NEVER has this car done this before. I called the tuner and he tells me to take my HPTuners and put the car back like it was before any tuning we had done that day. I did this and the problem is still there. I called him back and he tells me to try the car in both open loop and closed loop to see if the O2s are possibly bad. I tried that and it surges and backfires at low rpms no matter if it is open loop or closed loop mode. I can even make it backfire by placing the car in neutral and reving the engine to about 1800 rpms for 30 seconds and letting off on the accelerator...then 2 to 3 seconds later it backfires. Like I said, nothing mechanically has changed in the past 2 years and now it is acting like this. Does anyone have any suggestions? The tuner said the engine never ran rich enough to foul any of the plugs during the test and tune. However, I haven't had time to check yet, but I am thinking possibly one or more plugs maybe fouled/loose/not igniting......which is what I am expecting. I hate checking those damn plugs....especially #8. But before I do this, I really need some input here.

 

Anybody?

 

So anybody got any suggestions????

 

Quite a coincidence that you would have a blow out then the car started surging right after that. Last winter my car would start surging randomly. I was getting moisture in the 02 sensor and it was causing the car to have real low end type bog then it would randomly wake up so to speak and drive like normal then bog then wake up again but it was random. After pulling my 02 sensors and letting them dry out I didn't have a problem since. Mainly due to the fact that I don't drive it in the rain or snow anymore.

Some engine type surging is caused by ineffiecient ECM fuel/air mixutre. This can be due to a number of causes. Poor fuel pressure, plugged fuel filter, vacuum leak, exhaust blockage, transmission/clutch slippage or general valvetrain failure. I would also do a code scan on the computer to see if it's throwing you any codes that haven't appeared on your gauges yet.

Check those things and get back to us and let us know what you have done and haven't done.