How to cure backfire?

**Wheeler99WS6** · 10-15-2006, 04:54 PM

Mods in sig, ever since headers and exhaust installed it will back fire when i let off the throttle sometimes. It even backfired when i started it up today, kinda embarrassing. What are some remedies to possibly cure this. I just got NGK TR55 IX plugs and am gonna have them put in shortly, would that cure it? I am not sure to be honest as what to do about it. I plan on tuning it soon too but will that help it either?

**0rion** · 10-15-2006, 06:23 PM

The first thing I would do is swap back in your stock MAF and see if that clears it up. Other than that it sounds like a tuning issue probably if your O2's are functioning properly.

**Wheeler99WS6** · 10-15-2006, 07:11 PM

I will try the stock maf but I have no cats therefore no rear o2s. so i am not sure if that matters or not in this case.

**LS2Tuner** · 10-15-2006, 07:41 PM

It starts under "open-loop" which means it doesn't even use ANY of the 02's until they are up to temp. and "cycling". If you wouldn't of made the comment about it doing it at idle I would say it sounds like you have a leak and it sucking air and causing it to backfire.....

**0rion** · 10-15-2006, 08:25 PM

Originally Posted by LS2Tuner

It starts under "open-loop" which means it doesn't even use ANY of the 02's until they are up to temp. and "cycling". If you wouldn't of made the comment about it doing it at idle I would say it sounds like you have a leak and it sucking air and causing it to backfire.....

good call on the open loop. I missed that one.
My buddies C-5 was having a backfire issue and it ended up being a burned plug wire. It was laying on the header and cracked it. His was also cutting out under hard accel though.

**LS2Tuner** · 10-15-2006, 09:38 PM

**Wheeler99WS6** · 10-16-2006, 04:50 AM

well it doesnt do it when the car is idling, I meant that it did it just after firing up. when it idles it doesnt do it, it only did that once right after start. usually if it will do it, it will be when i am driving on the interstate going 60-70mph and let off to slow down. Does that sound like something that the Gmaf would cause? I tried getting it to do it last night and it wouldnt backfire. I was trying to see if it was only doing it around certain rpm or anything but couldnt get it to do it at all. So it doesnt do it all the time but just when i am not expecting it and it pisses me off.

**SeVeReDiStOrTiOn** · 10-16-2006, 08:54 AM

Originally Posted by Wheeler99WS6

well it doesnt do it when the car is idling, I meant that it did it just after firing up. when it idles it doesnt do it, it only did that once right after start. usually if it will do it, it will be when i am driving on the interstate going 60-70mph and let off to slow down. Does that sound like something that the Gmaf would cause? I tried getting it to do it last night and it wouldnt backfire. I was trying to see if it was only doing it around certain rpm or anything but couldnt get it to do it at all. So it doesnt do it all the time but just when i am not expecting it and it pisses me off.

That sounds like a backpressure pop to me...not a backfire. It's normal with exhaust on these cars...mine does it all the time when letting off the throttle, especially on the freeway.

**Wheeler99WS6** · 10-16-2006, 08:59 AM

So is it a bad thing? I mean hurtful on my engine? And how do I fix it?

**98Camarod** · 10-16-2006, 12:19 PM

Mine pops every once and a while. I installed lt headers and ORY. From what I understand the way to cure it would be to remove the air pump, but then it will throw a code until you have it tuned out. The pop can also come from the gapping on the spark plugs if it is not correct. When I put the headers on, the former owner left an original wire and two original plugs one of which arced.

**Wheeler99WS6** · 10-16-2006, 03:31 PM

well maybe when i put in my NGKs that will fix it. we will see

**ProwlerZ** · 10-19-2006, 01:22 PM

Just to let you know, the Tr-55s won't fix it. It's a backpressure "pop", caused from the equalizing pressure in your true duals/LTs. I bet you have 3" piping right? I've got the same thing going on, I'm used to it now, but to the untrained ear, I know people are hearing the "pop" and the cam's idle, and thinking the car isn't running well...hehe.
And before you ask, I'm running TR-6s now for Nitrous' sake, no change from stock ACDelco plugs to TR-55s to TR-6s, at least not as far as the pop goes.

**Wheeler99WS6** · 10-20-2006, 09:11 AM

thanks for the help

**Danger731** · 10-20-2006, 10:59 AM

Mine does it when cold and it lasts till almost at idle. As soon as I push the clutch in when its cold it pops. Didn't do it stock but with the LM it's carazy.

**89LX** · 10-20-2006, 11:41 AM

Mine has had the same pop in the exhaust since I purchased it stock. Put on Hooker Aerochamber CB and helped a little. Once engine is warmed up no more pop. I read numerous when cold most all LS1 have the same.