Let me start off by saying i'm religious about warming my car up ever time I get into it. I always let it do its whole warm up cycle where by the neg. boost always drops to -20 and rpms are a little below 1000k.

My problem has only happened twice now, that i've physically noticed, but with 11k now on the odo. this is what happens.

The engine is gradually lowering rpms...and put put out of the exhaust its minutely sputtering almost....its kind of weird.


(1.) I have just the Hahn 3" Cat-back and no other mods

(2.)-It has only happened TWICE to my knowledge, and only after the cars sits for about 3 days on both occasions.

....both times i was standing outside the car listening, and i don't know if its physically the engine or maybe the pressure in the exhaust is at an exact pressure where it would make it rumble funny....but its pretty noticeable.....more noticeable then the 1000's of other warm-up cycles i've listened to in the past.

Guess we'll see what happens...thats what warranty is for.

Thanks for the input.

 

I get that same thing. At initial start up the rpm sits at around 1300rpm and gradually over time it lowers to about 900rpm, but on its slow decent down the rpms it will every now and then stutter, and feel as if it would almost decide to stall then go back to normal. I only have the CIA downpipe, catted.

 

its the car warming itself up for you,