I replaced the plugs and coils recently and the engine is running fine when not cold. But when stone cold (within 2 or 3 min of start up after being off overnight), the engine is just a bit temper mental. Not that it stalls, just that it feels like it "might" stall and I have to be bit more careful and give it a bit more gas when the light turns green.

It's an 02 with 56K mi. I'm just wondering if I should look into cleaning the MAF or replacing the oxygen sensors. My 01 Boxster needed the oxygen sensors replaced at around this stage in its life. The Boxster showed a CEL but the 996TT has not thrown one yet.

Ordinarily this slight power loss off the line wouldn't be something I'd lose sleep over. But I wanted to get the engine ship shape before I do a 1 Bar flash.

 

Problem solved. It was indeed the MAF.

Removed it, cleaned it with CRC SensorKleen (I went looking for CRC MAF Cleaner and found this instead; maybe it's sold as SensorKleen in Canada. The can specifically mentioned cleaning MAFs, safe for plastic and no residue).

Car now accelerates smooth from a stop even when stone cold.

I could see some grime on part of what could have been the sensor area of the MAF. I sprayed everything, waited until it dried (literally seconds) and did it again twice.

This was the easiest thing I've done so far on the 996TT. I wish everything else was so easy about this car....

 

What kind of air filter do you have?

I didn't think the DME relied on the MAF very much on cold start.

You might consider a new maf at some point- the sensor gets a deposit from the repeated internal cleaning cycles that cannot be cleaned with solvent...the solvent does help, and will clean up a sensor fouled with oil/grime...but eventually they need refreshing. Just keep it in the back of your mind for later...

A