So over the weekend I installed a Gemballa sport exhaust on my 996 C4 cab. I am noticing something when driving that is really bothering me and I need to find out if any of you with any aftermarket exhaust have experienced the same thing.
Im driving along(this happens in any gear at any RPM when i punch it moderate hard through to WOT). I noticed I was at 3k RPM in i think 3rd gear and punched it, it went to 4k RPM then dropped back down to 3800 RPM then back up again. Is this something that is normal upon new exhaust system being installed on the car? Does it go away? Is it just due to ECU adjusting? Thanks in advance.

 

I've never noticed a 3rd gear, 4000rpm problem - you'd be going 45-50mph at that point, Porsches should be loving life at that engine speed. I'd get that checked.

 

your obviously not getting a CEL... that sounds very odd... could be a variocam timing issue... was your exhaust brand new or used?

 

Well its not just there, it seems to be the case no matter the gear or RPM. The exhaust was just installed so i hope its just a matter of adjusting the car to the new component.

 

There wasn't anything on this topic in Joel Riser's PCA Tech section, but this link to a rennlist test raises some points about air density, remapping, "hunting" etc...

http://www.rennlist.com/996_faq/e.htm

"...it is essential with OBDII cars to allow plenty of driving time for the system to adapt and make any gains it's going to...The OBDII unit takes time to re-map. Driving hard for a couple of hours helps speed this process. Some on the list started out with flat spots and other disappointing results after installing their after-market exhausts, only to find that later the power came back with just a hair more to boot."

 

NIKAS, youre a life saver man. Thanks for finding that link for me. +1 rep for you man, that couldnt have been easy to find as id checked over there but could find nothing.

 

So, remember i was having trouble with my new gemballa exhaust. the rpm's were dropping. i had the MAF changed(under warranty) and the plugs checked. no probs there. found out after that it was clutch slip. had the clutch discs changed today and the problem is gone. SOOOOO HAPPYYYYYYYYYYYYYYYYYY!!!!!!!!! IM BACK BABY! now for headers and intake.

 

Hey C4... glad to hear you solved your problem... initially I was going to suggest it was your clutch but when you mentioned the reves shot up and then back down again that was wierd.... I had a simllar situation before my clutch went but my revs were shooting up and there was no acceleration.. there was never any dip back to a lower rpm...

anyways... good show... how many miles did you have on that clutch?

cheers
Pete