View Full Version : Backfire

12-15-2006, 12:34 PM
So I've been having this probalem lately that evreytime I floor my car it makes popping noises like backfiries and the boost goes all over the place. It usually happenes if I just mash the pedal wether it be a rolling WOT or stopped and then go WOT.

12-15-2006, 12:39 PM
I dont have a VAG com at the moment but there is no CEL, I scanned it with my OBDII and the only code I get is P0422 because I'm running a testpipe. I also noticed it only happens when I hit full boost then it starts to backfire and feel like a surging/stutter.

12-15-2006, 12:43 PM
check plugs icm and maf.

12-15-2006, 12:45 PM
id def say check plugs!

12-15-2006, 12:56 PM
If a spark plug doesn't fire the fuel ends up in the exhaust and backfires. Don't even bother checking the plugs, just replace them. If the problem still exists then the ICM/POS is next in line.

12-15-2006, 03:16 PM
I also have been having this exact same problem. I have replaced the plugs and properly gapped them. I also replaced the ICM last summer. To the best of my knowlegde I dont have any vac leaks. I seldom get a CEL but a couple of weeks ago I did. VAG stated there was a misfire on cyl 4. Is there a chance that cylinder 4's coilpack is going bad? I have an AEB motor and from what Ive heard the coil packs are pretty solid for that engine code. At this point I dont know what else to do.

12-15-2006, 03:44 PM
man you guys need to test parts before you replace them.... icm's aint cheap and i know coil packs aren't either. you should do a little better job of diagnosing a problem before you just start replacing parts.

as for help with your problem. check spark plugs see if they are all firing(namingly number 4 from what you have said) then test your wires and look them to see if they have tears or holes, maybe it's shorting out somewhere. test your coil packs, see if those are working properly. and last but not least, i believe your local auto zone or parts store or even a shop should be able to test your icm if you can't do it yourself. just remember, start with the basics first. good luck man[up]

12-15-2006, 03:49 PM
My ICM went bad so thats why I had to replaced it. I know number 4 is firing too but its just at high rps I get the popping/studdering and fluctuations in boost. I know my BPV, N75, spark plugs, andFPR are fine. I am just thinking its either a coilpack or a maf sensor. I have been diagnosing this problem for some time.

12-15-2006, 03:52 PM
yeah i just replaced my plugs last weekend, and im still having the same problem. replaced my icm about 5 months ago, so thats out. i guess its the maf?

12-15-2006, 03:56 PM
or coil pack....or as simple as your spark plug wires....

12-15-2006, 07:12 PM
you guys need to swap around your coilpacks and see if you get the same results.. from what you find at that point you should know what to do, hopefully..

12-16-2006, 08:05 AM
you guys need to swap around your coilpacks and see if you get the same results.. from what you find at that point you should know what to do, hopefully..
That's a good method....if it's a misfire, move around the CP to see if the misfire follows. Of course, you really need vagcom for that.

12-16-2006, 08:26 AM
yeah, without a vagcom, switching around coilpacks will result in the same problem just a different cylinder correct? damn i need a vag com,
is it smart to rule out my icm? i just changed it 5 months ago!

12-16-2006, 08:31 AM
nope, can't rule out anything. I've heard of mafs/ICMS going dead very quickly.

12-16-2006, 08:51 AM
yeah but if its misfiring under boost wouldn't you get a flashing cel or a pending code?