ToxicDoc
Veteran Member
2001 Jetta, has .216 injectors, Kerma's "S7" turbo (BV39 with manual actuator), a PD150 intake (with an adapter to keep the stock EGR/ASV), and a Malone tune that was customized to this combination. The vehicle ran great, but during the quarantine it sat mostly unused for 2 years.
Now, it has overall low power, boost comes late or minimally, and brakes do not have much power assist now. CEL comes on.
On inspection I found two cracked vacuum lines that went to the ASV that I repaired. Vacuum pump had a loose nipple and slightly low suction (just feeling it with hand over barb). I replaced the O-rings, peened the housing down around the barb (got snug), and sealed it with epoxy. Vacuum good by feel. No improvement running.
I tested the N75 valve - works correctly when I give it 12 volts, switching open and closed. Unplugged the MAF and the brakes worked as they should the first time I stepped on the pedal, then lost most of the assist as it had been - no improvement in running. I tried another one I had from another car - no change either. Turbo actuator moves freely. All vacuum lines look good, nothing loose.
I had a recent promotion at work (I call it my demotion from all the extra work) and have minimal time to work on this. My local guru has cut back significantly on his work aside from a few track customers due to a serious family tragedy and won't take my car.
So, I take it to a local shop that does German cars. They clearly don't know TDI. They get codes P1556 and P0402. They replace the vacuum pump saying it wasn't working well enough (clearly not true) and the EGR valve. No improvement. They report the turbo actuator moves correctly. I take the car back before they start changing more parts.
I'm in a small town. The next closest recommended TDI shop is 2 hours away. I can take it but it's a hassle to go the distance, and I wonder if it's a good idea to drive up and down my local hills with no power and weak brakes. So I will look at getting a RossTech cable next. N18 is original. I will test it when I have time although not sure it would create a problem like this. In the meantime I would appreciate some diagnostic advice.
Any clues? thanks.
Now, it has overall low power, boost comes late or minimally, and brakes do not have much power assist now. CEL comes on.
On inspection I found two cracked vacuum lines that went to the ASV that I repaired. Vacuum pump had a loose nipple and slightly low suction (just feeling it with hand over barb). I replaced the O-rings, peened the housing down around the barb (got snug), and sealed it with epoxy. Vacuum good by feel. No improvement running.
I tested the N75 valve - works correctly when I give it 12 volts, switching open and closed. Unplugged the MAF and the brakes worked as they should the first time I stepped on the pedal, then lost most of the assist as it had been - no improvement in running. I tried another one I had from another car - no change either. Turbo actuator moves freely. All vacuum lines look good, nothing loose.
I had a recent promotion at work (I call it my demotion from all the extra work) and have minimal time to work on this. My local guru has cut back significantly on his work aside from a few track customers due to a serious family tragedy and won't take my car.
So, I take it to a local shop that does German cars. They clearly don't know TDI. They get codes P1556 and P0402. They replace the vacuum pump saying it wasn't working well enough (clearly not true) and the EGR valve. No improvement. They report the turbo actuator moves correctly. I take the car back before they start changing more parts.
I'm in a small town. The next closest recommended TDI shop is 2 hours away. I can take it but it's a hassle to go the distance, and I wonder if it's a good idea to drive up and down my local hills with no power and weak brakes. So I will look at getting a RossTech cable next. N18 is original. I will test it when I have time although not sure it would create a problem like this. In the meantime I would appreciate some diagnostic advice.
Any clues? thanks.
