[shaheenis]

Hi there,

I own a Cayenne 958.1 2011 S V8 for 18mths with full service history and generally well looked after. It has ~80K miles, only gets filled with 98+ RON fuel. It has had Variocam fixed, coolant cross over and TSTAT done.

The car is pinging very noticeably under load at low revs. At first I thought it might be a rattle in the TC chain or chain cover but pinging is pretty unique sound so I am quite certain it is.

I have read numerous threads with nothing definitive. Plenty of people say this is bad and just as many say this is standard. I know that pinging at low revs is often factory tune related as the manufacturer is trying to reduce fuel consumption and emissions under ‘normal driving conditions. I suspect but am not sure this is the case with my beast. Could it be related to dirty intake ports? How can I confirm the cause? I do not trust an Indy or dealer not to waste a lot of my money for potentially nothing.

Any checks I can do or things I can outrule myself would be appreciated. Part of me wants to ignore it, part of me is embarrassed I drive a Porsche with a Porsche engine that pings and the other part of me is concerned it could get worse.

Cheers,

Tim

 

[deilenberger]

Tim,

I'm surprised you're hearing audible pings.. the engine management should retard the timing to eliminate this. Certainly people have encountered carboned up intake valves on DI engines.. but I can't say I've heard of pinging as being a sign. Usually it's a rough idle that's the clue.

 

[Boristhespyder]

It's difficult to believe this is a standard amongst all Porsche V8 motors, as a manufacturer they are meticulous.

 

[shaheenis]

Well guys there is plenty of people claiming they experience exactly the same thing on the V8s but most appear to be non-turbo versions. Including the following statement from another forum "According to PAG, minor knocking, pinging or pre-detonation is somewhat normal on all V-8 equipped Cayennes. On some models, it's more noticeable than others. Most owners don't even hear it however, start out in 2nd gear and drive slowly next to any wall or barrier with your window open and it'll be obviously noticeable."

Problem is no one gets a resolution to the problem that I have seen and it appears that there are never associated engine codes and no one is posting any performance issues or engine failure as a result. This leaves me wondering why it happens?

After doing some research on engine pinging there are four likely causes:

1) Ignition timing is too advanced (could be factory tune related for emissions at low RPM)
2) Lean Fuel Mixture (could be dirty injectors or low fuel pressure impacting atomisation)
3) High compression (resulting from carbon build up in combustion chamber)
4) Overheating

4) should not be an issue because the car is not overheating
3) is likely a contributing factor due to these engines being direct injection, would need to get a camera in there to confirm how bad the combustion chamber is.
2) I am not sure this would result in only pinging at low revs. Thoughts? I would expect this to get worse under higher loads and RPM. This would be hard to troubleshoot. Injectors would need to be removed and checked. Intake valve carbon deposit could be a factor and weak fuel pump could also be a factor although this would likely get worse under higher RPM when the car needs more fuel pressure.
1) is likely a contributing factor given it is only noticeable at low RPM situations.

Thoughts?