Hello All,
I have been trying to remedy this problem for some time. This is on a 2003 MKIV TDI with the auto transmission. If I accelerate at a brisk rate, such as 3/4 or full throttle, the turbo boost and acceleration is good till the rpms hit about 3000-3400 then power drops off, rpms drop off, and usually goes into limp mode with no boost at all and a CEL. Restart engine and repeat. If I let off the throttle, and vary the throttle position I can avoid the limp mode most times, but of course I am not accelerating like I should be!
I have tested and replaced the MAF with a known good from my 02 and still have the problem. I have checked and replaced the N-75 turbo boost solenoid valve, still have the problem. I had first tried NEW ones of both the above, but was unsure if they were defective, so did the swap with my known good ones to be sure.
I have a VAG-COM and have run the test for the turbo boost vacuum actuator and the linkage arm moves back and forth to the extent I would expect is full range, about 3/4-1". I have also disconnected the vacuum hose and used a handi-vac type hand pump and it moved the same.
Does anyone know of more tests I could perform to figure this out?
The car runs good otherwise, and doesn't burn any engine oil.
Some of my thoughts are that it could be carbon build-up cutting down air flow in the turbo? Maybe choked airflow in the intercooler area?
The engine in this car was swapped out with a good lower mileage engine before I purchased it 4 years ago, by a diesel mechanic who also did work on VW's, and I believe he said the intake was in good shape/clean before it was put in. The timing belt kit was done at that time also.
Any suggestions are appreciated, THANKS!
Jeff
I have been trying to remedy this problem for some time. This is on a 2003 MKIV TDI with the auto transmission. If I accelerate at a brisk rate, such as 3/4 or full throttle, the turbo boost and acceleration is good till the rpms hit about 3000-3400 then power drops off, rpms drop off, and usually goes into limp mode with no boost at all and a CEL. Restart engine and repeat. If I let off the throttle, and vary the throttle position I can avoid the limp mode most times, but of course I am not accelerating like I should be!
I have tested and replaced the MAF with a known good from my 02 and still have the problem. I have checked and replaced the N-75 turbo boost solenoid valve, still have the problem. I had first tried NEW ones of both the above, but was unsure if they were defective, so did the swap with my known good ones to be sure.
I have a VAG-COM and have run the test for the turbo boost vacuum actuator and the linkage arm moves back and forth to the extent I would expect is full range, about 3/4-1". I have also disconnected the vacuum hose and used a handi-vac type hand pump and it moved the same.
Does anyone know of more tests I could perform to figure this out?
The car runs good otherwise, and doesn't burn any engine oil.
Some of my thoughts are that it could be carbon build-up cutting down air flow in the turbo? Maybe choked airflow in the intercooler area?
The engine in this car was swapped out with a good lower mileage engine before I purchased it 4 years ago, by a diesel mechanic who also did work on VW's, and I believe he said the intake was in good shape/clean before it was put in. The timing belt kit was done at that time also.
Any suggestions are appreciated, THANKS!
Jeff