Hey. If I press in the clutch to change gears while I'm accelerating I sometimes (about 50% of the time) get a very low but significant "boom" or "pop" from the exhaust. It happens at around 3k rpms and above. My performance mods right now are: DP, N-tech high flow cat and M2 Dual tip CB. Any ideas as to what this is? Anybody else notice this? Thanks.

-Matt

 

It's not because you're letting off the clutch...it's because you're letting off the gas after acceleration. The excess fuel is then igniting in your exhaust.

No biggie. It's to be expected when you only have a hi-flow cat.

 

Great. Thanks for the response. When you say "only have a high flow cat," do you mean that this will not happen when I do other upgrades? On the 30th of this month, I will be putting in a pfc (getting it tuned an KDR), pettit IC, fuel pump, apexi intakes, and 1300 inj. Will the pfc control my fuel system better so this will stop happening?

 

I meant that as more restrictions are removed from the exhaust end (dp, midpipe, hi-flo, or catback), then you're more likely to backfire.

When your upgrades are in and your PFC tuned, then you should be able to avoid excessive backfiring since the PFC won't run too rich, but you should be a little on the rich side anyway to avoid detonation.

KDR will take care of you, but make sure you install your PFC first before adding all those other mods.

Just so you know....all modern cars will dump a little extra fuel through the engine after you let off the gas from accelerating, simply because it takes a split second for the car to realize what you've done. It works both ways as well....the car will run lean for split-second if you're cruising and decide to go WOT. KDR will know how to tune for this.

Good luck

 

Thanks!