animull

My 03 996 began showing excessive carbon deposits in, on and around the exhaust tips and on the bumper at about 6k miles. 1st warranty service attempt indicated it was a PVC valve that was out of spec. Drove it for a few thousand more miles and no difference. 2nd warranty service attempt they stated it appeared to be happening after the engine was turned off as they could not find any abnormal data on the OBC readouts. They dropped the exhaust on the right bank (left exhaust tip) and noted excessive carbon on one of the exhaust ports. They supposedly found that the injector was leaking gasoline into the combustion chamber so that on start up, excess carbon was resulting leading to the problem. They changed the injector and cleaned the exhaust tip. After a few more thousand miles now, it appears the carbon problem continues. Curious if anyone else has seen this problem or knows of a resolution?

djantlive

Can you post pics to show how bad is your carbon build up? Is there any exhaust leak and which tip do you have? Do you see smoke upon startup or during hard driving? Your plugs may be fouled somehow due to the leaky injectors.

animull

No smoke on startup or hard driving. I've not pulled the plugs to determine if they appear fouled and the car does not feel as if it is running on fouled plugs. The mechanic indicated that the voltage from the distributor was so high, plug fouling would only happen under extreme conditions such as valve or ring damage. I thought it could be because the majority of my driving is inner city (sorry to say) but why the carbon would only appear on one side is the mystery.

Appreciate any other thoughts or if anyone has had similar experience and resolution.

1999Porsche911

What does your scanner show for fuel trim and secondary O2 sensor readings at low rpm? Don't have a scanner...get one if you want to properly diagnois any new car. Could simply be a lazy primary o2 sensor on that bank making you run rich at low speed.

animull

Thanks - Don't own a scanner. Any suggestions on what/where to get one, and what expected specs should be?

1999Porsche911

If you do a search here, you will find several suggestions. The one I have is a PC based program that is no longer available. Make sure it shows you at least the following live readings:

Engine Load
Engine Temp
Engine Compartment Temp
Timing
Fuel Trims
O2 Sensors
MAF

mundman

www.autoenginuity.com

I purchased the one for my PDA. Its great $199 on Ebay
Also comes with a dyno program called Speedtracer