CobraGSF

iTrader: (2)

Hey guys hopefully someone can help, heres the situation...

running the joe z catback & joe z intake with f-sport filter on my is 350. The exhaust does backfire when slowing down, when the car downshifts from second to first thats normal and I've seen it in other threads as well. but heres the thing, lately I've noticed that when the car is downshifting and i DO NOT have my foot on the brake pedal or accelerator when the car is just rolling to a stop and the car backfires it jerks forward a little. its like the pressure from the backfire pushes the car forward a bit. its like you hear that pop from the backfire and the car pushes forward a little exactly when that occurs. when i have my foot on the brake and it backfires this does not happen from what i remember.

is this normal? or should i be concerned? i know the dealer would probably blame it on the exhaust.
thanks guys a little worried so would really appreciate any advice!

AIK

iTrader: (1)

Upvote!!! I have the same problem too. I hope someone can help us out. Thanks!

goldengame

How much of a push is it? I have a fully stock setup and I can feel a subtle push when it downshifts from 2 -> 1.

brendanf

Are you downshifting it yourself into 1st? Because you really don't need to. Even people who drive stick rarely go all the way down to 1st because of the intense braking effect it generates

I'd avoid going into first and let the car switch to first on its own after coming to a complete stop.

Jskrapper

+1
and


+1

It is normal for a free flowing exhaust to "pop" or "gurgle" or "burp" on higher rev decel. But an actual backfire is hopefully not what you getting. I'll put money on the fact that it is the cars natural (or your own gear selecting) downshift that is slapping it into first. Also, in sport + mode, the downshift is much more "slappy".

Vivid101

this is normal. when the car is going a little fast for 1st gear. Engages into first, engine revs up, car nudges forward and then starts to slow down via the transmission if not on the brake.

CobraGSF

iTrader: (2)

phew , thanks guys. good to know I'm not the only one experiencing this. and this would occur when the car is in auto not manual. so it would be downshifting on its own. i guess his tranny just downshifts hard into first?

dnasians

iTrader: (4)

this would be true for most cars

goldengame

I don't think that it's because the transmission downshifts hard into first, I think it's because first gear (at least in my AWD) has a fairly aggressive ratio so the difference between first and second is bigger than the difference between second and third.