mkiv808

My 2011 Cayenne S was brought in for the camshaft bolt issue, which Porsche covered.

I've noticed the vehicle can have a very slight rough idle at times, especially when cold. Figured that was normal.

Recently a CEL came on. Evap system very small leak. Replaced fuel cap and reset CEL, but it came back.

Then, this morning on a very cold start, I was idling at a stop light and it started idling very rough, the CEL was blinking, and PSM failure and start stop deactivated warnings came on. I immediately stopped and turned it off. When I turned it back on, it was fine.

Any insights on what might be going on here? Trying to decide between taking it to the dealer that did the camshaft work if this could at all be related, or if emissions warranty could pay for whatever is causing the very small leak. Other option is one of my Porsche indies.

mkiv808

Ran codes, nothing new. Still P0456

deilenberger

P0456:

• Missing or loose fuel cap
• Incorrect fuel filler cap used
• Fuel filler cap remains open or fails to close
• Foreign matter caught in fuel filler cap
• Evaporative Emission (EVAP) canister or fuel tank leaks
  
• Evaporative Emission (EVAP) system hose leaking
• Fuel tank leaking

There'ya go. Simple enough to check most of these. One possibility might be that one of the evap hoses going to the intake system on the engine was damaged when the Variocam adjusters were done (at a minimum the valve covers have to come off)..

mkiv808

Could that cause a misfire?

deilenberger

I don't believe you mentioned a misfire.

Describe it..

mkiv808

See original post, I believe blinking CEL denotes a misfire and the car was barely idling - very rough and seemed like it would stall at any time.

deilenberger

The CEL blinking means "Shut it off".. and a leak into the intake from the EVAP system could cause rough idle, low idles speed and stalling.

I'd take it back to the dealership and let them sort it out.

mkiv808

Bad evap pump, replaced under emissions warranty.