Is it too rich or too lean or something else?

[brewerbry]

I am stumped again by this car! When accelerating hard, foot to the floor, revs hit 5500 or so and the power drops way off and it feels like the rev limiter kicks in, the tranny stays at the high rpm and does not shift until you slightly let off of the gas. The shift is pretty abrupt once it occurs.

I think it is engine problem but I guess it could be tranny (it is tiptronic with 40,000 miles). I plan to do a tranny service (can't hurt since the records do not show it was ever done).

Any ideas about what else it could be? Running too rich? Too lean? How can you determine the difference?

Car and tranny runs fine just drivjg around town and only acts up when you have fun and step on it.

Thx-

[JFP in PA]

If the car was too rich or too lean, it would throw codes accordingly.

[brewerbry]

That is what baffles me - I does not throw a code! I have a new MAF sensor and new front O2 sensors and this just starts happening randomly...

[mikefocke]

Are they Porsche or Bosch parts? Have you looked for any pending codes?

[brewerbry]

The fix was as simple as cleaning the old MAF and resetting the ECU. I have no idea if the new MAF was the culprit but I really do not care at this point since after cleaning and re-mapping the ECU, the car runs fine with the old MAF.

Whew, that was stressful but thankfully a simple fix.

[Pdwight]

How did you accomplish this ?

[brewerbry]

I assume you are asking about reset / remap of ECU? I disconnected the battery and left it overnight. While disconnected, I pulled, cleaned, and reinstalled the MAF sensor. I reconnected the battery, turned the key to accessory position for a minute, removed the key, waited 5 minutes, started the car, and then drove it for 10-15 miles. The car ran like garbage at 5500 rpm+ before and now it is back to normal.

[johnsjmc]

Do you have a K&N air filter? The oil used on them can foul a MAF sensor.