I've noticed this problem when i first put my CA XTC High-flow cat Downpipe on, Pretty much immediately. About half throttle in second/third gear 3-4rpm car will Jerk through the RPMs a few times. I dk if you've seen the power curve for these 08 2.4's but it's almost picking up like i had seen the hp/tq numbers on the dyno. With stock DP on problem goes away completely.. (So does the power of coarse) But beside that, i love the power it adds on this car I'd like to get it back on the dyno.

 

Did you reset the ECM and drive it normally for an hour or so?

 

Yupp, It wont do it when i'm "normal 3k" shift driving. Just spirited, and i'm not talking about pedal to the floor. It grabs hard around 4-5 k when I've got it WOT. I just can't figure out what it could be about the DP that is causing it.

 

so your saying it gained a lot of power "snap" at 3-4K rpm?

 

No, when i'm driving "normally" but just letting it rev a bit higher the car will jerk/buck

 

oh, ok. i just couldnt understand from reading it. are you tuned?

 

No Tune, Waiting for HPT to come through for us 08' Guys. Should have seen the stock dyno run. Instead of smooth curves, it had spikes. Almost is running like the dyno would have shown it. I just don't understand. I'm sure it can be corrected with a tune but GM factory tune reacting like that to a dp?