deezulmark
Veteran Member
As of August, I'm the proud owner of my first TDI - a 96 Passat wagon. I'm very pleased with the car but it has one odd problem under hard acceleration.
In normal unhurried driving I'm always upshifting probably well before 3000 RPM. But if I push it hard coming up an on-ramp it will frequently "hit the wall" somewhere between 3000 and 3500 RPM. It will be accelerating nicely and then all of a sudden it refuses to get any faster. It won't lose any RPM, but it acts very much like a governor kicks in. The sudden capping of RPM can be pretty abrupt sometimes.
Doesn't happen all the time but a lot of the time. Seems to be most prone when pushed the hardest. If I work it up a little slower I can get to 4000 RPM with no hiccups and I've never tried to push it higher.
The previous (original) owner reported a probably related problem with occasional power loss with the cruise on at high speed. He would disengage the cruise and the clutch and let the RPM down momentarily and then stomp on it and it would recover and he'd re-engage the clutch/cruise. I think I had this happen to me once on a long hill at 70+mph. But the acceleration problem is very frequent. When I hit the wall I just upshift and it is fine in the next gear. Previous owner had a lot of basic things checked and even replaced the wastegate solenoid but never figured anything out.
My first thoughts have been around the turbo end of things as well. Is there some kind of overboost protection that maybe the sensor is a little too sensitive and opens the wastegate a bit early? While we're on the subject - is there a popular (and relatively inexpensive) manifold pressure gage that can be installed. I'm just generally curious to know how much boost is going on and when.
Otherwise the car is still going strong at 215K miles. Can't argue with a car that can take a family of 4 and all their junk on a road trip and get 46-47mpg. Still runing dino-diesel but plan to start using B20 soon. Just used PowerService fuel additive the last two tankfuls (1000mi+ each!) with no improvement other than apparently cleaning out some soot which showed up as a light spot on the garage floor under the exhaust pipe which was wiped up and has not reappeared.
Thanks for whatever help anyone can offer to figure this one out.
Mark
In normal unhurried driving I'm always upshifting probably well before 3000 RPM. But if I push it hard coming up an on-ramp it will frequently "hit the wall" somewhere between 3000 and 3500 RPM. It will be accelerating nicely and then all of a sudden it refuses to get any faster. It won't lose any RPM, but it acts very much like a governor kicks in. The sudden capping of RPM can be pretty abrupt sometimes.
Doesn't happen all the time but a lot of the time. Seems to be most prone when pushed the hardest. If I work it up a little slower I can get to 4000 RPM with no hiccups and I've never tried to push it higher.
The previous (original) owner reported a probably related problem with occasional power loss with the cruise on at high speed. He would disengage the cruise and the clutch and let the RPM down momentarily and then stomp on it and it would recover and he'd re-engage the clutch/cruise. I think I had this happen to me once on a long hill at 70+mph. But the acceleration problem is very frequent. When I hit the wall I just upshift and it is fine in the next gear. Previous owner had a lot of basic things checked and even replaced the wastegate solenoid but never figured anything out.
My first thoughts have been around the turbo end of things as well. Is there some kind of overboost protection that maybe the sensor is a little too sensitive and opens the wastegate a bit early? While we're on the subject - is there a popular (and relatively inexpensive) manifold pressure gage that can be installed. I'm just generally curious to know how much boost is going on and when.
Otherwise the car is still going strong at 215K miles. Can't argue with a car that can take a family of 4 and all their junk on a road trip and get 46-47mpg. Still runing dino-diesel but plan to start using B20 soon. Just used PowerService fuel additive the last two tankfuls (1000mi+ each!) with no improvement other than apparently cleaning out some soot which showed up as a light spot on the garage floor under the exhaust pipe which was wiped up and has not reappeared.
Thanks for whatever help anyone can offer to figure this one out.
Mark