Cayenne High Speed Idle after warm up

[Henry Fox]

2006 Porsche Cayenne S (non-turbo)

This Porsche has a high speed idle at about 1800 rpm. However, this only occurs after the engine warms up and the transmission is in ‘park’ position. When first started the idle is normal for about 20 minutes – then slowly speeds up to the 1800 rpm. After is has developed the high speed idle – if you place the transmission ‘in gear’ the engine speed drops to 600-700 rpm. The car does not seem to be straining in gear – but at idle until you increase engine speed – then pulling away normally.

Also, after the high speed idle has established itself, if I turn off the engine and immediately restart the engine - it will idle at 600 rpm, momentarily before it returns to the high speed idle. Performance of the car is normal when driving – responsive and powerful.

Occasionally the P2187 & P2189 engine codes (system lean at idle) will appear. After a CEL code reset – they re-appear after several days of routine driving. Using these codes as a troubleshooting guidelines – I have: 1) tested fuel pressure on both fuel pumps, 2) examined the PVC valve for leaky membrane, 3) pinched off the vacuum hose to the purge control valve, 4) inspected the gas and oil cap) and inspected vacuum hoses. None of the items appear to be at fault.

This suggests that the high speed idle is being impacted by operations of the computer. Suspicion of a vacuum leak seems unlikely since the idle can be returned to ‘normal’ instantly by transmission position or the turn-on and turn-off scenario.

Any suggestions or help would be much appreciated.

[fintstone]

Just saw this problem. What was the solution?

[fintstone]

Thinking Air oil separator. Ordered parts.

[fintstone]

Mine had this problem plus a lot of oil smoke on startup. Air Oil Separator (@$65) fixed this. Thought I had lunched my engine. Whew!

Could not find anything obviously wrong with old part.

reset codes with a Durametric.

[Jbdehoyos]

I had to do my Air/Oil separator, but it was on a V6. Pain in the ass since the whole intake has to come off to get to the valve cover. Took a day.

[fintstone]

You don't have to pull the valve cover, just the oil air separator cap, spring, and diaphragm. Takes about 5 minutes.

[Bigtoe32067]

I’d check for vacuum leaks too if not the separator
Tony

[Salina]

I would have offered to change the oil as it is very often the main problem and the most simple topanimalreview 
..I don't think the oil, but actually replacing it all at once becomes good

[guru944]

Engine Oil filler cap, Seal goes bad....Had this issue last Year...

[JBKauai]

Originally Posted by Jbdehoyos

I had to do my Air/Oil separator, but it was on a V6. Pain in the ass since the whole intake has to come off to get to the valve cover. Took a day.

Originally Posted by fintstone

You don't have to pull the valve cover, just the oil air separator cap, spring, and diaphragm. Takes about 5 minutes.

He was talking about a V6, so the air intake manifold does have to come off to get to it. I'm going to be doing this soon, and am not looking forward to it.

[fintstone]

Yep. Keep forgetting some of these have a V6. At least the part is cheap.