emission issues (or is it plugs?)

[9Firty]

I have recently taken delivery of a 2001 996TT but appear to have an issue. Here's what happens -

Under acceleration the car gets to about 4500 revs and the engine starts to splutter, the tacho shudders and the car loses all torque (when I say 'loses' I guess I back off straight away but you get the idea) If I do this two or three times the 'check engine' symbol comes on along with 'drive to workshop." From my own (limited) knowledge of these things and from consulting the manual I believe the issue relates to emission control, namely one or more sensors not working correctly. As I understand it, the computer is incorrectly mixing the air and fuel due to incorrect readings coming from sensors in the emission control.

There is actually a second part to this problem now too ... I've noticed that the car feels a little 'rich' and jumpy in first gear below 2,000 revs. It almost feels like it bogs down off the line and then jumps away above 2,000 revs as if it's too rich down low or something. I'm wondering if the two issues are related? It doesn't do it in other 'acceleration' gears but I think that's because you tend not to go below 2000rpm in 2nd and 3rd.

Anyway after all that I guess my question is - has anyone had this issue with their car or does anyone have any experience with this problem? The car is going into the shop next Tues anyway but I'm keen to know as much as possible beforehand.

Thanks

Simon

[Aerkuld]

Although I have no first hand knowledge of this problem I would like to recommend something to make your life a lot easier. Try getting a Durametric diagnostic tool. It can hook up to your car and will probably tell you EXACTLY which sensor(s), or whatever it is that is causing the problem. Believe me, it will be the best money you ever spent.

[9Firty]

thanks so much Aerkuld ... I'll see if I can locate one and report back.

Cheers

[Britwrench]

How many miles?

Report back with the OBD2 numbers, but probably mass-air flow sensor.

Other possibilites are spark plugs (which don't last long anyway) or excessive carbon due to the "short trip" syndrome.

A note on diagnostic tools, it does not tell exactly which sensor is faulty, it relays the readings from the sensor... you go from there.