Hi guys,
ever since purchasing my
06 Cayman S
8 months ago, i've noticed that every once in a while when aggressively rev-matching, there's a loud 'pop' that comes from behind me. Since the car exhibit no other problems since day 1, i didn't look much into it since it's pretty rare for me to jab at the throttle that much during day-to-day driving.
I was bored today during a meeting so i did a little searching on CC and came across a "sound diagnostics thread" which contained an entry for this:
POP: This sounds like a shotgun being fired through a mattress. It usually means the engine's coughing back through the intake. A sticking or leaking valve is a distinct possibility, as is jumped valve timing, particularly with a belt-driven OHC. Then there's ignition, which may be firing way too early due to a twisted distributor, cap/rotor/wire problems, a faulty position sensor or a breakdown in the module. Also, if your
Porsche
's running quite lean, opening the throttle to lots of cold air can induce this reaction.
Since it's very hard to replicate the noise, i was wondering if there was any way i can point my dealership in the right direction should i bring the car in.
anyone else experiencing this? the only time it's happened is when i'm cruising to a stop to a red light, the light turns green, and i jab at the throttle to bring up the RPM to pop into gear and take off.
thanks !
EDIT: i also want to add that i started having this problem since purchasing the car stock, and actually have not been able to recreate it since the RS350 kit 5 months ago.
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Gilles,
thanks for your input. sounds like most of the suggested causes aren't applicable in our case.
since the RS350 kit appeared to have 'fixed' my problem, perhaps the flapper valve is the culprit... but does that mean EVERYONE has this problem and i'm the only one that's whining about it?
what if that's not it, but i've just adjusted my driving habits to not cause the problem anymore? what else could it be?
I get the same backfiring sound when I aggressively rev-match every now and then, and from everything I've read on this forum, it's completely normal
Diabolus
thanks for chiming in. if it is normal, i wonder what's causing it? any side-effects?
Here's a thread I found on the subject. There are a couple others I've seen floating around but I can't seem to find them right now. Seems like it's unburnt fuel in the exhaust system that's causing it
http://www.planet-9.com/cayman-chat/7352-backfire.html
x2 except i don't really rev match like i used to. A lot more subtle and smooth with it now.
