First post on here as well, i've just bought an audi.
Picked up a 1999 110 tdi last sunday very cheap. Its in good condition but is down on power by a lot.
When I bought the car the guy said it needed a maf and fuel cut off n109, I took my ross tech vagcom lead along and sure enough these where the two faults logged, I cleared them and went on a test drive, the car was down on power and struggled to rev above 2500 rpm and the two faults re-appered so thought its defo a maf problem and drove the car away thinking I had a great deal.
When I got home I decided to take a closer look around the engine and found that the n109 fuel cut off had been hard wired to the battery 12v thus keeping it open. Thought this was strange as if the n109 was knackered then a 12v wouldn't open it. I disconnected it from the n109 and tried to connect to the ECU with vagcom, I was persented with a 'cannot connect to controler' error. When I reconnect the 12v to the n109 I am able to connect to the ECU!
I Replaced the MAF to see if this was causing the loss of power but its the same, it just wont rev. The MAF fault has not come back since I replaced it.
The timing belt seams quite old so i presume the timing is ok and all the vac pipes seam to be in the right order.
I've checked all fuses and the 109 relay, the n109 wire to the ECU is fine but there is no 12v from the ECU pin when there should be.
Im thinking the ECU is a knacker job but just wondering if anyone could shed any light on this problem or suggest anymore tests I can do before I buy a new/e-bay ECU.