When i'm really pushing the car, like when racing, between shifts i get a small pop backfire out the exaust. It only happens when i shift really fast, when i let up on the gas to shift, then put the gas to the floor. Only at WOT. I have a gutted cat, and 3" cat back. I get about .96 o2 in second gear, wich is a bit rich, but is this normal to have? I never got this when i had my stock injectors in. The car runs great, and pulls hard otherwise. Just wondering. Maybe i can lean it out some, but I just dont want to push that..

very normal..just means your running a little rich...better safe than sorry

I believe this is normal when you're running rich, and if you have a test pipe or gutted cat. I also noticed more "pops" when I gutted my cat. It also made me worry at first.

I know it's normal for rx-7's to do that because they run rich, so I'm assuming its ok

heh not only do they run really rich they run extremely hot

anyway I"m running freakishly rich and I don't get pops even when autoxing or racing, it could be your misfiring. How much boost your running? Then again I have a cat and my engine is pretty jacked up so I doubt it will ever detonate unless I run out of fuel :P

What about backfiring when slowing down?

(not trying to steal your thread Matt)

Thanks for the help guys, yeah i thought it was fairly normal, as i am running a bit rich i suppose. Like i said though, it ONLY happens when i shift really quick, where there is just very quick letting off the gas then back on it between shifts. If i reach full boost, then shift a tad slower, its not there. It doesnt do it if i just back off the gas either...Matt, i think you have pretty much the same issue as i do..prob just running to rich.. Its just unburnt, leftover fuel igniting..

When my tranny shifts, there's a 'fart' like flutter. I'd assume it's the same reason?!?!?

with my gutted cat my car will backfire whenever I shift like you do, but only on the 1-2 shift. You should have somebody ride around behind you so they can tell you what the flames look like, I thought it was kinda cool when I found out that I shot big blue flames out my exhaust.

Are you sure that your car is backfiring as your slowing down?? I get a kind of gurgle while slowing down while my car is in gear but it is definitely quiter than when the car backfires.

Robo, one of the guys in my car club gets a fluttering sound when he is getting on it and his tranny shifts too. Hes the only auto in the club, so I dont know if that is normal or not. He is a chrysler tech though and he said he has checked everything out and all is fine. If you want to talk to him about it just email me and I will give you his contact info.

>>>Are you sure that your car is backfiring as your slowing down?? I get a kind of gurgle while slowing down while my car is in gear but it is definitely quiter than when the car backfires<<<


Good point. Let me rephrase that. When I slow down in gear my exhaust "pops" I guess it's not really backfiring like you guys are talking about. Probably because there is a lot less fuel.