Power low under heavy acceleration

[Denis O]

I have a 1999, 996 Cab Tip and find that under heavy acceleration the power delivery is not smooth. Best way to describe it is almost missing but not quite. It does accelerate pretty quick but seems to hold back and be a little "fluffy".

Seems to be the same in either auto or tiptronic mode.

It is due for service in November and I can live with it till then as long as the problem isn't causing any other issues.

Starts and runs fine, hot or cold, under normal driving. Just when I give it some beans.

I usually run on regular unleaded. Would going to Optimax or similar help or is there a more serious problem at large here.

[800]

Does it happen at 2000-2500 RPM and drop the revs by 500 or so, before going again?

[Denis O]

It's more noticeable from 4000 up but it could be lower. Maybe because I expect it to deliver more at higher revs.

[911 habit]

It sounnds like a air or fuel blockage to me.
Get it checked out at an OPC ASAP.

[McP]

Could be a faulty mass air flow sensor. Had a similar problem earlier in the year with my 996. The car felt like it was 'missing' at just over 4000 rpm - almost like a flat spot in the power delivery. Linking the car up to the PST II diagnostic computer will show an error code for the MAF sensor if it is that.