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Pete
Pete, Technician
Category: Porsche
Satisfied Customers: 26750
Experience:  17 years automotive training and experience.
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Cayenne S: At about 85 degrees F, and stop and go traffic,

Customer Question

At about 85 degrees F, and stop and go traffic, my Cayenne S stalls out. It then starts right up. It is also jogging down at about 1800 rpm. I kick down a gear and it recovers. I am thinking some kind of vapor lock. But this did not happen last summer with higher temps. Fuel pumps are fine. 2008 Cayenne S. Any hints?
Submitted: 1 year ago.
Category: Porsche
Expert:  Pete replied 1 year ago.
My name is ***** ***** I am a professional here at Just Answer. I noticed that your question had not received a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here. If the check engine light has come on with this issue here the first thing that needs done is to have the fault codes read out/checked to see what codes are setting with this issue here.If the engine is stalling out coming to a stop and is bogging down like this this can be an issue with the transmission torque converter itself engaging when it shouldnt be and can be an issue with the lock up solenoid for the torque converter or an issue with the torque converter itself.I have seen both cause this type of fault here before.I have also seen issues with the crank position sensor itself act up intermittently and cause a stall out like this here.Both of these will need checked into to locate which component here is at fault and then repaired from there. If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service.You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.Thanks Pete
Customer: replied 1 year ago.
Pete,
I was not clear enough.Car has no problem idling.
Upon take off as the RPMs rise to 1500 or so with moderate acceleration, the car can stall at that point.
If I either baby the accelerator past 1500 RPM, it doesn't stall out.
If I am going lets say 40 MPH, and the motor running at 1800 RPM, it will start balking. When I downshift raising RPMs, it runs fine.All this occurs above 85 degrees external temp and the engine well warmed up.My thinking is that it is vapor locking in the engine compartment in one of the fuel lines. For some reason, at low RPM, it does not vapor lock. I have explanation for that. At 1500-1800 RPM, the flow is just slow enough to allow the vaporization of the fuel in the very hot engine compartment. And at higher RPMs, I can see that the fuel flow through that line is rapid enough such that it will not vaporize the fuel. The fuel does not have time enough to vaporize in these heated conditions.I have had the car about 14 months. It did not happen last summer. But then again, I did not do as much stop and go driving as I am now...Right now I plan to figure out where the fuel lines are in the engine compartment and wrap with thermal tape. Any other ideas?Dan
Expert:  Pete replied 1 year ago.
Is or has the check engine light come on with this issue here at all?
Customer: replied 1 year ago.
No check engine light. It is as described above twice. It seems that wrapping the fuels lines in thermal tape did the job. Thanks for trying. Dan
Expert:  Pete replied 1 year ago.
That is great to hear you have resolved the issue.If you need anything in the future let me know. Thanks Pete