Plastikos

Sooo...

'04 CS with 157K. For maybe two week, first noticed after a 4 hour road trip, car has an occasional engine hiccup at idle, feels like a misfire. Interestingly seems a little worse when placed in reverse - thats actually when I first noticed it. Also seems worse when driven, parked for a while, then driven again. NO problems whatsoever turning over, or running under throttle, or cruising. Really only seems to be idle or very low throttle. Took it to local non-dealership, and managed to coax one "misfire" out of it on test drive, tech agreed felt like a misfire. Of course, no codes have been tossed.

Spark plugs changed about 20K ago. Left sided fuel pump changed at about 130K. This weekend cleaned throttle body, also replaced a cracked crankcase breather hose (the one that goes to the AOS). No change in the misfire issue (does run a little smoother overall though).

Based off searching the forums and personal experience, does not seem like a fuel pump issue. Also, although coils of course come up seems like these should throw codes? And not be exclusively at idle?

Any thoughts / suggestions as to where to go next greatly appreciated!

Jeroen Pipelers

check your ignition coils for cracks

Dennis C

Sounds like it could be a cracked coil. My Cayenne ran really rough when the coils failed and it smelled like burning sulphur.

Plastikos

So it's recognized that the coils can go without throwing codes?

Dennis C

Mine did throw a misfire code when they failed. I'm not sure if they can fail without a code or not.

Jeroen Pipelers

If you search for ignition coils you'll see, there alot written about this. They all go bad. There is also a sticky.

mudman2

and they don't always throw a code

Lexlthr

I just went through the same thing. I would defiantly say ignition coils and or spark plugs.

Plastikos

Thanks I'll inspect them this weekend, coils at least. If it's a bad coil is it always visibly cracked?

Km1.8t

Coils, mine were all cracked when I changed them and no codes.

Plastikos

So I just wanted to follow up on this issue, now resolved.

Coils and plugs.

Over the past 2-3 weeks the roughness was getting worse, eventually started affecting low throttle situations. And finally thanks got the CEL went on and the codes pointed to missfire cyl. 7.

From my indy "So it looks like we have it figured out. Having lots of issues on the ignition side of the system. Found a misfire on cyl 7. Performed actual value testing of the stored misfires. Found that all of the cylinders have been having misfires some more than others. Cyl 7 the worst. Inspected coil and spark plugs. Spark plugs worn, also found arching going across the boot if the coil pack and around the core of the spark plug. Swapped coils and found misfires happening on cyl 6 with the coil that was in cyl 7. At this point i'm recommending replacement of all coils and sparks. Total on the job parts, labor and tax is $983.8. Let me know what you think. Also I attached a couple photos of the arching that is going on. On the spark plug its the black line going down the side is the arching going around the boot of the coil. "








Thanks for everyone who chimed in!

Borntovin

I am in same exact situation, and I am a new owner. Before buying the car, I drove the cayenne s 4 times and it did not feel right while leaving the parking lot. It was a nice ride while cursing. Before I knew there was any issue with the used car, I was considering a complete coil and spark plug change.
When I got the PPI inspection, cylinder 1, 5 and 8 had misfires. No CEL in the car. I bought the car anyways and I am about to change the coils and spark plugs myself. Here is a nice tutorial and thread that I have open.
You can get the parts for 350$ or less. And DYI or pay some one 100$ to 200$ for installing them. You are looking at 500$ to 600$ tops. You can save money and spend it to replace air and cabin filters etc.
https://rennlist.com/forums/porsche-...ft-sensor.html