Lumpy Running During Warm Up

robertfearnley · Dec 15, 2015

Hello everyone,

have been a member of Porscheclubgb for several months now, but this is a rare post from me. Im in need of a bit of advice, before I spend the money at a Porsche main dealer.

My issue is with my 997 Carrera 4S Cabriolet - Year 2007 - Manual.

The car runs lumpy until its fully to temperature. I start the car from cold and the car starts at higher revs while it is in the warm up stage. No issue there. It then backs off, and its at this point the car begins to run lumpy. Once it has run for about 5 minutes the lumpiness disappears and the car runs perfectly. When its running lumpy I get the Engine Management light come on too.

Today I took it to a friends garage (non-Porsche) and he took out the Mass Air Flow Sensor and cleaned it as someone suggested this could be my issue. It wasnt it runs the same!! He has a simple diagnostic system in his workshop and I have attached the pictures of what the readout said.

I'm wondering if anyone has had this issue and can tell me what the issue could be or how I properly diagnose it. His diagnostic is not specific enough to define the problem, so I could for example end up changing all lambda sensors when only one is gone.

Appreciate any advice

Many thanks

Neil

Gordon Attar · Dec 15, 2015

I would suggest taking it to a specialist for them to diagnose they don't normally charge for this service. I the past that sort of reading on a Porsche computer I. E. All 6 cylinders is usually the cylinder bank solenoid, theres one each side if it was showing a few you would suspect the coils.
Please visit a specialist first as the OPC could use those sort of readings to do you over.