Cayenne starting problem

[rjc]

I have a 2005 mnodel Cayenne S which generally I'm very pleased with. But on 2 occasions now (seperated by 6 months or so) it has had a strange starting problem. On turning the key to start the starter motor whirs at high speed as if the engine has no compression. After a bit of heavy gas pedal pumping it eventually starts with a lot of popping and banging and dark smoke from the exhaust. After that it seems fine and no warning lights or unusual indications occur. I met another Cayenne driver a while ago who said he's had the exact same problem and his dealer hasn't been able to diagnose it. Anyone else had this or have any suggestions as to the cause?

 

[tiskev]

I dont think I would keep depressing the throttle when it happens.
I have never had the engine exactly whir around when starting,if anything mine is sluggish.
I am wondering if it actually has no compression at the time because the hydraulic tappets
have jammed all the valves open.Perhaps one should ask Larry or an OPC if this is a possibility.I may well be talking through my hat .

 

[lazza]

I'll ask Les and advise any thoughts.

lazza

 

[Guest]

seems to be a relativelycommon problem - mine did the same every now and then. never really bothered me because 1) I wasn't planning to keep it (goodness knows what condition the cats were in!) 2)it always started but would just run a little rough for a few seconds.

 

[lazza]

I've had this from Les at Solihull.

"Its not some thing I have come across, from the description it sounds
like its not firing and then over fueling.
The only thing that springs to mind to cause this type of fault would be
a lack of signal from the cam shaft position sensor. The engine
management system needs to know where the cam shaft is so it can start
the firing order. If the sensor fails the management system will wait
for a signal whilst cranking, if it does not get one it will start the
engine on a nominal value (hence the black smoke).
This should be recorded in the engine management fault memory.

As she is still under warranty, best to pop it into a dealer to get the
fault memories checked first."

Hope this helps.

Lazza

 

[rjc]

Thanks so much for pursuing this for me Lazza. I haven't had the problem since writing the note but if and when it does it again I will take it in to my local OPC and have them check the fault memory. It's due for its first (20K!) service soon so maybe they'll find something then.

Best,

Robin