Car backfires after header install, tuning problem?

**BLCKBRD2000** · 08-09-2011, 04:38 PM

I recently installed TSP headers on my 2000 Trans Am. I removed the EGR and Air systems since these were off road headers. I had a preexisting Magnaflow Catback and the Y pipe that came with the TSP headers needed to be rigged to even fit under the car. The car began running extremely rich and back firing every time I tried to accelerate(not to mention have the entire shitty Y pipe slam the floor and make driving impossible) I recently just got the car back from having a muffler shop install a custom true duals setup, which I had them put in high flow bullet cats(yea I know but my area is a bitch with roadside inspections) and had the back O2 sensors reinstalled. The car now runs a bit smoother and backfires less but still has some major popping when I get on it. I have replaced and rechecked all the plugs and wires as well as tested all the coil packs. The car continues to miss every now and then as well as the annoying backfiring. I have yet to have it tuned and plan to do so but I want to make sure that I have covered all my bases so I dont get turned away when I go to have it tuned due to something I should have checked. Is it possible that not having the EGR and AIR systems tuned out will cause the car to run the way it has, or does it just need to be tuned in general since it was running slightly rich before the header install? Also it is a stock LS1 and no work has been done to the motor itself. Im just hoping somebody has gone through this before so I can drive my car comfortably again.(been about 3 months now) Thanks in advanced

**Z28Thunder** · 08-09-2011, 04:43 PM

Even without the EGR and AIR removal you need a tune if they replaced the stock manifolds. Headers flow much different and tend to make you run rich.

**cammed goat** · 08-09-2011, 04:48 PM

^^What Thunder said. Have the rear O2 sensors turned off and you will be fine. The extra exhaust flow with your factory tune is sending your ECM into a frenzy.

**BLCKBRD2000** · 08-09-2011, 05:14 PM

Thats what I figured. Of course now I have the rear 02 sensors plumbed into my new exhaust but whatever not worried about them. Once I get these retarded mufflers this guy installed on here cut off and replaced Ill get her tuned. Ever hear seen bullet mufflers that are the size of a full size muffler? My car is quieter after installing headers and duals lol

**0rion** · 08-09-2011, 07:01 PM

tuning never hurts and after headers a tune is recommended but what you're describing isn't a tuning issue. You have a mechanical issue somewhere. You say you have the rear O2's hooked up.....what about the fronts? Any exhaust leaks pre front O2's? Check plugs to make sure you didn't crack one on the header install and check your plug wires to make sure none are burned or not seated down all the way. Check your front O2 harness and make sure it hasn't melted against a header. Make sure your egr and air ports are all blocked off. If it's backfiring after a simple header/exhaust install it's a mechanical issue.

**Vexzer** · 08-09-2011, 07:22 PM

Originally Posted by 0rion

tuning never hurts and after headers a tune is recommended but what you're describing isn't a tuning issue. You have a mechanical issue somewhere. You say you have the rear O2's hooked up.....what about the fronts? Any exhaust leaks pre front O2's? Check plugs to make sure you didn't crack one on the header install and check your plug wires to make sure none are burned or not seated down all the way. Check your front O2 harness and make sure it hasn't melted against a header. Make sure your egr and air ports are all blocked off. If it's backfiring after a simple header/exhaust install it's a mechanical issue.

Yeah, what Orion said. Quit "checking" the wires and replace them. Be sure the new ones do not touch anything en-route to the plug, especially the headers, make sure they are pressed fully on and not "stretched" or under stress. Secondary 02's are not and do NOT affect operation, they only monitor cat efficiency. You have done nothing that asks for a tune, but when you get one turn off the secondary 02's. Since the car has been screwed with, no way you crossed sides or changed the harness and switched fronts with rears? I don't think you can easily do that.

**BLCKBRD2000** · 08-10-2011, 08:14 AM

See thats what im worried about. Both plugs and wires were replaced while i was installing the headers. All the egr/air valves are all plugged up, and i have both the front and rear o2 sensors functional in my new setup. Last night i removed all the plugs and wire and checked them for any damage as well as all the harnesses going to the o2 sensors. I cannot find anything mechanically wrong with the car that would cause this issue. Im honestly stumped other than taking it to get tuned. The backfires are basically occuring when I get on the car and they are like a sucessive popping noise. Really losing my mind over here.

***SMWS6TA*** · 08-10-2011, 09:11 AM

you didn't splice in extensions? If you did then that could be part of the problem.

You will always have a little pop/back fire with headers. Mine seems to only do it when I let off after a high rev.

**BLCKBRD2000** · 08-10-2011, 10:52 AM

Nah i got the plug and play extensions and as far as I can tell there isnt really any issues with them. The backfiring literally criples the car. I mean my next step was to buy new front O2s and see if maybe the sensors are just worn. Just an expensive maybe answer to my problem.

**BLCKBRD2000** · 10-05-2011, 01:25 PM

Just to resolve my own problem I did buy new front O2 sensors and that didn't do anything so after awhile I got pissed and started from scratch again. Pulled all the wires, plugs, sensors, etc. Found the cylinder 7 plug had a hair line crack in the porcelain and since I couldn't find anything else I went and bought a new plug, popped it in and car runs perfect. Its always some tiny stupid bs. lol