Andy Schmidt

Relative newby here- I’ve got an idle problem and have searched the forum and don’t see much of a fix identified…. I’m a second owner of a ’07 TT, 6 speed, 28,000 miles. I’ve had the car three years so I know it well. It has a stage 2 europipe exhaust and ipd plenum (I didn’t put that on… first owner- hear it’s not as good as advertised). I don’t think it’s chipped.
About 9 months ago I started getting a searching idle when the car is warmed up and no a/c on. When coming off throttle to a stop the idle comes down to 1250rpm and hangs for 5 to 7 seconds before dropping down to stock idle. If I have the ac on (load on motor) it doesn’t do this. Also noticed that when cold it works fine. I took it to dealer under warranty and they replaced the throttle body. That sort of helped but not for long.
My indie was also stumped- thought vacuum leak, but none present, and then he punted when he saw that I had an aftermarket plenum and that Porsche calls for a 2008 throttle body when replacing one for a 2007…. I think he just didn’t want to chase this one.
It's not throwing any error codes.
Any ideas?

DINOROCZ

my first guess would be to check the spark plugs and coils. After that there are many directions to go so I would start with the plugs/ coils.

Also my guess is that the car does have a tune, very few will go through getting an exhaust and plenum but not a tune (when everyone knows a tune yields a good bit of power for the money)

jhbrennan

I have essentially the same...08 TT 6MT with EP2 but without the IPD plenum and no problems...so maybe the best place to start is to replace the IPD with stock plenum. Might also want to find out for sure if previous owner tuned the car. Good luck - always difficult to diagnose problems like this. Good luck.

Macster

Would be interesting to see the MAF reading, TPS reading, along with the short term fuel trims over a span of time that includes the before, the during, and the after of the idle searching event.

For these you will need an OBD2 scan tool that can obtain these values and store them for later downloading and import into a spreadsheet or some program and render them human readable.