Loud bang in third gear

[seanco]

I have found similar posts, but nothing really particular to my problem.

I recently installed a downpipe. The check engine light did not come on after installation, much to my surprise; as i was anticipating it. After installation when i was driving pretty hard in third gear, i heard a very very loud bang (almost like a gunshot) and my car stopped accelerating. My natural reaction was to let off the gas, so i can't say if it was a fuel cut-off or the degree to which it stopped accelerating. At this point my check engine light came on, and remains on. I am confused because I though my check engine light should be on because the downpipe eliminated the cat? If so it is odd it wasn't on in the first place. Any ideas why this "bang" happened, and if so how I can fix the problem, if it even is one?

Thanks!

 

[mattdev]

Sounds like a misfire. Did it sound like a backfire? If the ecu senses even one misfire the CEL stays on. If you can get ahold of a logger, or take it to autozone they can tell you exactly what the CEL code is, then check back here or your service manual for more info.

 

[crimsondragon]

Sounded like a backfire if it was a bang. The ECU does not check the rear O2 sensor for your cat unless the car is in cruise mode above 40mph for more than 30 minutes I believe. Mine didn't come on for the longest time till about 2 weeks later after my turboback install.

 

[6bolt_tsi]

Does the car still run good?

 

[seanco]

It did sound like a backfire to me. And yes, the car does seem to be running fine. I haven't really noticed any differences.

 

[xi Talon ix]

just think of it as a burp

 

[seanco]

If that is the case, is there anything I can do to stop that? Or is this just a normal event??

 

[xi Talon ix]

dont quote me but your ECU might have to adjust because your moving the air out of your engine faster so in return it has to bring it in faster to compensate. it was probably just a misfire because the ECU hasnt made proper adjustments yet. if it worries you, you can unhook the negative battery cable for 30 seconds and hook it back up because then the ECU will be "reset".

 

[seanco]

Ok thanks, ill give that a try, this is with the car on or off??

 

[xi Talon ix]

keep the car off and then unhook the negative cable.

 

[seanco]

ok thanks, Ill give it a try today after work. Ill let you know how it goes.