snapdragon
Veteran Member
I have just replaced the VNT-20 (GT2052V) turbo on my Passat (MY 2002) it is 2.5TDi V6 after a faulty actuator with blown diaphragm.
Now I have underboost and dissappointing acceleration until about 3000rpm, where there is a sudden boost beyond belief. When I hooked up VAG COM, there are no fault codes.
I got some boost actual vs. requested graphs which should be below, and there is also a link to the same pictures on flickr which can be viewed full size, they show too-little boost until around 3000rpm, then too-much. I have tested the actuator with vagcom and it moves excellently, and the VNT mechanism is free.
I have checked all of the vacuum pipes and they seem OK, the N75 valve is only 9 months old, and I don't suspect it because it moves the actuator with VAG COM in 'basic settings'
I can't think of anything else to try, the only thing I can think of is that my old turbo had a G on the end of the part number and this one an F.
Green - Requested manifold pressure
Yellow - Actual manifold pressure (lower of two pale lines)
Gray - N75 duty cycle (higher pale line)
Red - RPM
http://www.flickr.com/photos/13666355@N00/sets/72157600156139841/
Now I have underboost and dissappointing acceleration until about 3000rpm, where there is a sudden boost beyond belief. When I hooked up VAG COM, there are no fault codes.
I got some boost actual vs. requested graphs which should be below, and there is also a link to the same pictures on flickr which can be viewed full size, they show too-little boost until around 3000rpm, then too-much. I have tested the actuator with vagcom and it moves excellently, and the VNT mechanism is free.
I have checked all of the vacuum pipes and they seem OK, the N75 valve is only 9 months old, and I don't suspect it because it moves the actuator with VAG COM in 'basic settings'
I can't think of anything else to try, the only thing I can think of is that my old turbo had a G on the end of the part number and this one an F.
Green - Requested manifold pressure
Yellow - Actual manifold pressure (lower of two pale lines)
Gray - N75 duty cycle (higher pale line)
Red - RPM
http://www.flickr.com/photos/13666355@N00/sets/72157600156139841/
Last edited: