Loss of power - no check engine light

[fernando306]

If flow is restricted, and the DME adjusts fuel to match the available oxygen, then the downstream O2 sensor can be happy, even though you have less power.

This sounds fantastic. I would not be surprised at all if that is exactly the case!

Maybe I can try disconnecting the post-cat O2 sensors and see what happens?

The whole car maintanance is completely up to date. The only thing left unseen are the cats.

[fernando306]

My friends,

Took the bimmer out for a longer drive and, she's back to being the peppy punchy car I've known all the way to the rev limiter.

If I were to guess, I'd say the O2 sensor was probably the culprit, as those were original with 112k on them. But I've changed plugs and put a fuel cleaner for good measure.

[colb]

Bad Maf can result in the lack of power you are getting.Disconnet the electrical plug on the Maf and the car will resort to factory default settings, see of that improves power, if it does then replace maf with OEM Bosch or Siemens brands nothing else

[x-driver]

I'm having maybe the same problem ever since I bought the car half a year back. It's a 3.0i, but feels like 2.5i or less. Above 100km/h it gets lazy. The car has 110k km. Runs smooth however.

The car has new spark plugs. Cats were checked with a camera through O2 sensors holes, they look perfect. O2 sensors look fine. Fuel pump pressure was measured and is ok. Valve cover gasket is replaced, CCV is new. Air intake is ok.

Any other ideas? I haven't checked MAF yet however...

[x-driver]

I ended performing a dyno test which showed the car is totally fine I guess I just expected too much.