05 Cayenne S transmission - almost stalling engine when halting

[bigbuzuki]

Changing the engine mounts on the Cayenne S should not be an expensive exercise as it can be done without the engine being removed.

[wvicary]

OK, here's the rundown: The idle RPM stumble issue still isn't fixed - bad as ever.

The explanation that we have come up with: Engine is fine. Transmission is fine. Driveshaft is semi-fine. But: The combination of engine mounts AND drive shaft may cause my issues.

When I take my foot off the gas, the engine goes from load mode into follow mode - causing the engine to 'wiggle' a little in the engine mounts. That wiggle then translates onto the driveshaft, which, in turn, also wiggles a little. By the time both wiggling has caught up with the new load circumstances, it comes as a jolt on the idling engine, which causes the engine to spool up slightly to account for the perceived drop in RPM - sending another jolt through the accumulating wiggle rooms. That way, this stumbling can travel back and forth along the engine mounts and drive shaft several times before it stabilizes.

This is frustrating, because to fix this would cost thousands. Anyways, I have learnt my lesson. Porsche's are one-way cars. Drive it for three years - then toss 'em. Or, if you plan on keeping your Porsche: Make it a decorative objective in the living room, and de-dust it every once in a while. That's about it.

I have had Mercedes, BMW, even Audi's with VERY high mileage - and never had any issue that would not have been fixed within a thousand dollars or two. But tens of thousands for a simple clunk? Thank you.

WHAT?!? Is this what the OPC told you?

[Mongoman]

That's exactly what I was told. I'm just frustrated.

[Ricky1]

I know nothing, so far, about the CS's 6 speed auto transmission, but I believe I have experienced "The idle RPM stumble issue" in a Nissan before. The Nissan has a CVT attached to a torque converter that locks above a certain speed (18Km/h I think). There were times when slowing down for a red light, the idle would dip pretty low (below idle speed) before what seems to be the lock on the torque converter releasing. Does the CS have a locking torque converter? Just throwing in another idea...

[paulwu]

I

On 5/10/2013 at 11:47 PM, Mongoman said:

That's exactly what I was told. I'm just frustrated.

Have you fixed the rough idling issue at the end? I am having exactly the same issue and very frustrating too.

[phil nickisson]

try checking the vacuum hoses.  Mine have just split and the idel was rough as anything...replaced them and all good.