A6 2.5TDI Severe performance loss????

[niriley]

Hi I have just purchased a 1999 A6 Avant 2.5tdi - thought I would be pleased and doing the right thing (reliability etc etc)

After 1500 miles and 3 weeks of ownership it has started to play up!

Starts and idles beautifully however as soon as I put my foot down all power is lost and the car comes to a standstill! In neutral the engine revs freely however under load / acceleration nothing just dies!

However if I drive on a VERY light throttle or using the cruise control no problems will go up to 80mph+

Any one any ideas. It is a tiptronic box (seems to all work fine) and covered about 90,000 miles.

Help............!:confused:

[Joshua]

Check Maf,N75.

Thats the first thing i would do.

[niriley]

I take it you mean the Air flow meter?

If so disconnected and drove down road - lots of exhaust smoke (black) guess over fueling but made no difference at all still same problem. When pedal is planted the engine dies!

[Joshua]

I take it you mean the Air flow meter?

If so disconnected and drove down road - lots of exhaust smoke (black) guess over fueling but made no difference at all still same problem. When pedal is planted the engine dies!

If you had vag com it would be nice...

Well it can be a leak, check you intercoller pipes and vacum pipes.

Here in Portugal it very hot and sometimes pipes crack...

The n75 is also worth a look, because it controls the turbo.

[niriley]

Well the car has spent 4.5 hours being diagnosed at Audi main dealer today! Unable to locate fault! They said may be a blocked crankcase breather will cost £350 plus diagnosis time but unable to guarentee!

Personally I think not crankcase, as no smoke at idle, not AFM as drove disconnected - I have seen lots of reference to this N75 Jobby causing the same problem.....

Anyone any other ideas?

[Joshua]

The N75 is a strong possibility, but they could test it with vag com.
In my car i had faulty(and still have:p )components but vag com showed no faults, these components (turbo,n75, maf etc) can be tested individualy and see if the values are correct;)

[spottedhaggis]

it has been suggested I check the connectors and wires for the MAF sensor, but I dont even know what it looks like let alone where it is in the engine, can anyone advise what to look for and where on an Audi A6 2.5Tdi V6 2003 model.

Thanks

[yaman]

it has been suggested I check the connectors and wires for the MAF sensor, but I dont even know what it looks like let alone where it is in the engine, can anyone advise what to look for and where on an Audi A6 2.5Tdi V6 2003 model.

Thanks

It sits at the intake side of the air-filter box and forms part of the tubing.

Looks like this: http://shop.ebay.co.uk/items/__audi+2.5+maf_W0QQ_dmdZ2?rvr_id=235792365466&clk_rvr_id=235792365466&crlp=2884525449_284591_284611&UA=WVF%3F&GUID=c6929b1e12f0a5a9c6b4fa74ffeb0755&agid=1237448859&tm_kw=audi+2.5+maf&siteid=3&MT_ID=10&tt_encode=raw&keyword=audi+2.5+maf&geo_id=21&ff4=284591_284611

Regards
Jim

[fjtwelve]

Not everything throws a VAGCOM code. My money is on the N75, or the boost pressure sensor, or a split hose in the intake system. I have had almost identical symptoms to you, the first time it was N75, at present not completely sure as problem is intermittent. Blocked crankcase filter would give white smoke.