924Board.org

[awilson40]

After adding a free flowing exhaust, I get a pit of popping when decelling, downshifting and, sometimes, when briskly upshifting. Mixture seems fine and all 'lambda' circuits are functioning. Is this normal when changing exhaust?
Thanks

[924RACR]

Not uncommon... I've got quite a bit of popping, with my MSDS header, 2.5" pipe, and single bullet (through-flow glasspack-style) muffler.

_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[jamez]

mine does the same thing too...

[bacook]

It can look really cool as well! Porsche better get their act together if they plan to ever beat these GTRs!

http://www.fastdetails.com/alms/pics/spBMW43Airwa8.jpg

[Zuffen]

Common problem it seems as I have it at times after a hard run. I wonder if the decel valve is loosing effectiveness.

_________________
Bob Dodd - 924turbo@cox.net
931 1982, 944 1982 euro, 924S 1988SE, 93 968 tip 06 Silver Cayenne S, 06 Black Cayenne S

I have Way too many cars, parts for the 931,944 and 951

[awilson40]

Thanks guys.
BTW... I removed the Decell valve on mine. It was working properly, but I saw no difference with it on. The plastic port on the intake that the decell went to had broken off so I just plugged it and removed the decell valve.

[eturbo924]

How is the car running otherwise? How is it under part throttle? Mine was acting similary until I retarded the timing just a bit. Seems I had it set to agressively. Not sure where it is at the moment. It is being painted at the moment. Anyway try a bit less advance and see what happens. Helped mine. I have bursh header and 2.5 inch exhaust. You can see my system on my site under my projects.

Eric

[awilson40]

Thanks, good idea. I might retard the timing a bit. I think I'm running a few degrees advance over spec. It runs great otherwise, no hesitation or flat spots. It has always idled a bit rougher than I would like but not too bad.