Help! Intermittent rough idle

[mwiadro]

I have an 04' Cayenne S w/ 87K miles. Last month I had a couple of episodes of rough idle/running. (No check engine light.) After ruling out a bad tank of gas and the return of these episodes, I visited my indie mechanic. Scan results showed misfire cylinder 2/6. We replaced the ignition coils at 2 & 6 and cleared codes. Truck ran fine for four or five days and then the intermittent rough idle episodes started again. The second episode triggered the CEL (solid) light. Brought the car in today and the following codes showed:

P0357 & P0021

After clearing the codes, the rough idle returned and I rescanned. P0357 was persistent.

The original coils were replaced under warranty/recall by first owner. Plugs were changed at 65K miles. Wondering if it's time to simply change the remaining 6 coils, or if there are other suggestions?

Many thanks, in advance, for forum input.

[ekstroemtj]

How you described the problem reminds me to my situation weeks ago.

The coils of course can be the problem. Maybe you should try to replace the remaining ones. Its not that expansive.

But back to the topic...... My problem with the rough idle was the fuel pump. Specially when you wrote it was working some days and after it came back. The reason can be the fuel level in the tank. With tank almost full it works. When you drive some days and fuel level is going down problem is coming back.

The car has 2 pumps. They working both only when you start the car and under full load. In other circumstances just one or the other is working . Search the forum please for

TESTING FUEL PUMPS. You will find some advice how you can find out more

[mwiadro]

Can anyone confirm the latest coil part #? The original coils were changed in 07' as part of a campaign. Those coils read: Beru 648 602 104 07 / 0 040 102 002. The two new coils I replaced read: Beru 0 040 102 012. I'm getting some conflicting info from my dealer part's counter. Thank you!

[Loren]

Can anyone confirm the latest coil part #? The original coils were changed in 07' as part of a campaign. Those coils read: Beru 648 602 104 07 / 0 040 102 002. The two new coils I replaced read: Beru 0 040 102 012. I'm getting some conflicting info from my dealer part's counter. Thank you!

Porsche part number 948-602-104-07 is the latest part (for a MY2004 Cayenne S).

[mwiadro]

Thanks, Loren!

[bigbuzuki]

According to Sonnen, the latest revised part number for the coils is 948-602-104-09.

sonnenporscheoemparts.com sells them for $37.39.

Edited January 17, 2013 by bigbuzuki

[Loren]

bigbuzuki is correct - when you try and order 948-602-104-07 it says use 948-602-104-09.

Apparently the price list is more up to date that the parts list!

[mwiadro]

Thank you, both, for the additional information. I pulled the engine cover to confirm part numbers - the coils replaced under warranty (2007) read: Beru 948-602-104-07 / 0 040 102 002 . (Is the latter part number for vw/audi?) The two new coils read: Beru 0 040 102 012. They seem to lack the Porsche part #?