smoke be gone! - VW TDI forum and Audi TDI forum

Hawkbox · #1 03-20-2012, 10:23 PM

2000 golf that driving me nuts. Blew the turbo up almost two years ago now and installed a new one along with timing belt and the works. Ran okay for a bit and then I could hear a hiss and after getting worse or a while it would go to limp. Ran it down to leaking exhaust gasket. Fixed that and it was better but never right right. Car would start up after cooling down completely and run pretty well, go somewhere, stop at the store, comeback and start the car and it would run like crap, tons of black smoke on acceleration and sometimes it sounds like the valves are clattering a bunch, so you back off the accelerator baby it for a while and sometimes it quits smoking and runs great and other times its like the cars in the new diesel commercial smog all the way home. I've done boost leak check and found nothing. Just seems like I get it right for a month or so and it acts up on me again.
Help me out here please!
thanks
mike

Hawkbox · #2 03-22-2012, 10:34 AM

So I replaced vacuum lines that looked suspect but check good. MAF sensor was giving some weird values so I cleaned that and it made a difference but driving and watching the screen is a trick. I got a code driving in to work this morning of 17964 so I'm thinking that I need to check the actuator and possibly the N75 valve or is there a way to check it via VAG Com that I'm not aware of, and am I on the correct path?
thanks

Keithuk · #3 03-22-2012, 11:15 AM

Welcome to the forum.

VAG Error Code: 17964
EOBD II Error Code: P1556

Fault Location:
Charge Pressure Control - Negative deviation

Possible Cause:
Reduced power output
Limp mode

Boost Pressure too Low.
Hoses/Pipes incorrect connected, disconnected or leaking.
Charger Pressure Control defective VNT (variable nozzle turbo): nozzles stuck.

Possible Solution:
Check Hoses/Pipes to/between Components.
Check Solenoid Valve for Boost Pressure Control (N75).
Check / Clean / Replace Charge Pressure Control Check / Clean mechanism for variable nozzles.
Solenoid Valve for Boost Pressure Control (N75) defective.

As taken from my Free EOBD II Error Codes software

Hawkbox · #4 04-16-2012, 10:24 AM

I spent my weekend tearing this thing apart and putting it back together. Low boost was from compressor wheel having something get in it and having the vanes wear down to nothing or so I suspected. Replaced turbo, cleaned everything, intake and egr, pipes, hoses, inner cooler, anyway it's clean. Replaced leaking cam seal and radiator while I had it apart. Oil change and new antifreeze. Fire it up and take it for a spin and no codes but it seemed like it went in and out of limp mode. It was late so I crashed and took it to work this morning. Again this morning no CEL but the black smoke was terrible at times and then it would go away only to start spewing black smoke again. So you start questioning yourself about what you missed? I set the actuator with a mytyvac and check all the vac lines that didn't just replace.?? So I stopped at the mid point of my travel and unplugged the MAF. No more black smoke. It ran smoother that it has in a while, a little less power going up hills but otherwise it ran better and no smoke. Bad MAF ??? I have at times seem MAF sensor readings at 1400+ at idle but it changes. ???

Hawkbox · #5 04-16-2012, 08:59 PM

I got home via unplugged MAF and hooked up VC lite to see what the MAF was doing and at idle I was @ 1285-1455. Took the MAF off and cleaned it and it made a big difference but I still don't think it correct. Going up a hill it tells me it should be seeing 825 or so and actual is reading 1250 constantly with no variation unless I release the foot pedal. Feedback appreciated.
thanks
mike