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05 Cayenne S - Entire Bank Misfiring at the same time?

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OK, this just keeps getting better. After having very odd rpm spooldown roughness issues that remain unaddressed, the car jerked on me shortly after a cold start like never before - even with the flashing CEL - that went away shortly after.

The codes were P300; P305, P306, P307, and P308. Now, all codes were clear before, and we only recently replaced all plugs and coils.

What's odd here is:

1) CEL went away after a few seconds

2) idle RPM went up the high 800s after this episode

3) ALL misfires occured simultaenously on the same bank, leading me to think it can't be the coils or plugs.

What on earth could that be? It's obviously not the bank's fuse, either, as it corrected itself.

The reason I'm so excited about this is that for the first time with my rough idle issues, the car has thrown some error codes.

Any thoughts? What could simultaneously "out" an entire cylinder bank?

I'm really thinking I might just drop it by the dealership and get it fixed for twice of what it's worth...


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We checked it today with ye olde Bosch KTS650 - P300, P305, 306, 307, 308 - all at the same time, starting with 800 RPM.

Position sensors checked out fine, too. Oxygen Sensors fine.

But: Everything else is fine, and the codes are gone. In short: I still don't know what was going on.

I don't think it would be the coils as we changed all 8 of them to the latest '9' series, plus there is no way on earth ALL four coils on bank #2 would fail at the very same second?

Am I wrong?

Our best guess would be either some weird ground issue on bank 2 or something with the camshaft position sensor; but again, we simply don't know.

This is what's frustrating: I've had Mercedes, BMW - in the dozens - and only two Porsches. I've never had ANY engine trouble - but I have CONSISTENT engine and transmission trouble with my Porsches that no one seems to be able to fix.

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Thank - really good step-by-step guide - yet, I think, the reason we haven't been able to put our fingers on it. In the P0300 code workup, the diagnostics stop at step 12 - as the suggestion is to proceed to step 12, effectively looping itself back to 12 gain. Does not make sense!

But I guess the answer to my problem is: It was an intermittent problem, and until it rears it's ugly head again - no way of finding out what it was.

Again, I'm very shocked at Porsche quality with apparently numerous single points of failure that not only leave you with a rough idle or a check engine light - but stalling engines, misfiring engines, and not starting engines at all. I'm seriously approaching Porsche's very cautiously know. I'm friends with a former chairman of the supervisory board of Porsche in Stuttgart, and for a fact I know that when the team first wanted to presented the Cayenne prototype to the board, the electronics had drained the battery overnight so that when the chairman sat in, it wouldn't even start! That apparently gave the Cayenne the dual battery layout down the road...

I'm just p'd off right now. Porsche'd off. I'll drive my Benz more I guess.

Thanks for all the help, though! You guys rock.

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Inspect the fuse for the coils pack for that bank, they can corrode or overheat and cause intermittent contact points, it's easy enough to replace the fuse and inspect the contacts for tension. I would also monitor the camshaft positions when these issues are occurring.

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Good idea - I have checked the fuse for the #2 bank, which is fuse 8 in the engine fuse box compartment - for loose or corroded contacts. Everything seemed very clear, the contacts were tight, no corrosion - I replaced both the #7 and #8 fuse, just to be on the safe side.

That really leaves me down to a fuel line problem, a camshaft position sensor problem - but as the problem occurred ONCE for a matter of seconds over the last 5.000 miles, testing WILL be difficult.

I may just have to wait until a completely failed CPS leaves me and the pig stranded on a steep mountain road, past midnight, in a freezing snowstorm. :cursing:

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Did the defect occur recently in the 5000 miles you have travelled or did it occur once 5000 miles ago?

If it happened recently I would just change the camshaft position sensor as preventative maintenance and rid myself of the worry.

Part number 99660610602.

Sonnen has them for $213.

Or you could try interchanging the 2 camshaft sensors for evaluation.

Edited by bigbuzuki
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  • 2 weeks later...

A common problem from that model series is bad coil packs (primarily cracked coils causing mis-fires). They likely need to be updated to the latest version.

I only have error code 0307. see: http://www.renntech.org/forums/topic/24374-need-help-2004-cayenne-s-cyl-5678-misfiring/?p=235737

Do I have "bad coil packs" or something else? What could it be?

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  • 3 years later...
On 3/27/2013 at 9:51 PM, rting said:

I only have error code 0307. see: http://www.renntech.org/forums/topic/24374-need-help-2004-cayenne-s-cyl-5678-misfiring/?p=235737

Do I have "bad coil packs" or something else? What could it be?


Problem is fixed.  Thought I can post my efforts here: http://rennlist.com/forums/porsche-cayenne-forum/748446-2004-porsche-cayenne-s-ignition-coil-defects.html

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