KasbeKZ

yeah two threads in one evening. sorry. i'm bored. couldn't combine these topics.

i guess it's been over the last few months that my car has started to back fire when i shift from time to time. it's a pretty mild back fire, but it's there. i checked the plugs to see what's up with them, and after about 20k on them, they still look absolutely perfect. a tiny bit of red on the white part and just a light colored dusted look for the most part. so possibly burning slightly hot, but nothing i'm going to worry about.

so, the questions: is it possible that without really any black at all on the plug that the car is still running rich? or is it possible that something is causing a rich condition only during the shifts? no BOV's, it's N/A.

on the exhaust, i have the pre-silencers removed and pretty cheap mufflers that the PO put on the back, with the tube silencers put in the ends of them. i'll post a pic if that's not a good enough explanation. i also have about 3 exhaust leaks that i know of, but i have at this point no reason to think that they could cause back fires. thanks in advance!

ZLover4Life

Exhaust leaks can certainly contribute to such problems. To ignite, fuel needs air and spark/heat. The exhaust is certainly hot enough to ignite fuel, but normally there's no air (oxygen) in the system. Enter an exhaust leak. During shifting and general vast decreases in RPM, pressure changes draw fresh air into the exhaust from the leaks. And now the fuel in the exhaust has everything it needs to ignite, thus backfire.

And are you seriously asking if a non-turbo car can run rich? OF COURSE.
Low resistance on injectors -> rich
bad MAF -> ECU thinks there's more air than there is -> rich
bad O2 sensor constantly yelling "lean" to the ECU -> ECU thinks engine needs more fuel -> rich
bad temp sensor -> rich
the TPS might even be able to cause such a problem

Pull ECU codes. Check injectors.

KasbeKZ

haha no i wasn't asking if a non turbo car could run rich. i just didn't want anyone to blame BOV's for a rich condition when shifting. a bit of a joke i guess.

thanks for the suggestions. i'll check that stuff out. exhaust leaks are pretty close on my list of stuff to fix.

KasbeKZ

haha no i wasn't asking if a non turbo car could run rich. i just didn't want anyone to blame BOV's for a rich condition when shifting. a bit of a joke i guess.

thanks for the suggestions. i'll check that stuff out. exhaust leaks are pretty close on my list of stuff to fix.