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Pete, Technician
Category: Porsche
Satisfied Customers: 27814
Experience:  17 years automotive training and experience.
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Multiply cylinder misfires. Running rough, I have not. I

Customer Question

Multiply cylinder misfires. Running rough
JA: Have you metered out the ignition system?
Customer: I have not. I replaced coil packs and plugs, which helped for a short period. Also brand new plugs are covered in carbon
JA: What is the model/year of your Porsche?
Customer: 2005 cayenne turbo
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: Yes, as I don't have the funds to take it to a dealer. So far just coil and spark plug replacement, as well as seafoam additive
JA: Anything else you think the mechanic should know?
Customer: Just multiple cylinder misfires.
Submitted: 11 months ago.
Category: Porsche
Expert:  Pete replied 11 months 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.

Since the plugs are covered in carbon soot this can be due to the engine running to rich which can be caused by a faulty mass air flow sensor sending an incorrect engine air flow reading.I have seen this sensor fail in the past before needing replaced for this issue here.I would check the engine air filter and replace it if needed and have the mass air flow sensor tested to see if it needs replaced or if it can be cleaned to correct this fault here.

In some cases this can be the egr valve stuck open needing replaced or fuel injector issues needing cleaned.This would need checked into further to pinpoint and repair the cause here.

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service,your 5 star rating is appreciated.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