So its been a few sordid months with my wife's TDI. Here's the history:
It started with hesitation and loss of power, and a blinking coil dash light. She took it in to a local mechanic and the second hand info I got was that there was "Something wrong with a flapper." My wife ordered a dieselgeek p2015 fix, and I helped get that installed last week, and thats when I got involved in this. After replacement, there really wasnt much of a change, so I pulled codes. We had a turbo Underboost code(P00AF, P0299), an EGR code (P0402), etc. Would not go over 2500 RPM. So after watching some of the vids on here, and based on the codes, I was thinking that the N75 or actuator was bad. I checked the vacuum system:
- First from the pump...28" consistently
- I checked the turbo vane actuator - held vacuum without loss.
- Then the N75 - I dont have VCDS (it arrives Tuesday), but Tee'd up Vac gauges on the pump to N75 inlet, and in between the N75 and Turbo Vane Actuator. It was inconsistent when it called for vac, so we just replaced it (N75).
The N75 behaved much better after that. I cleared the codes, and went for a test drive. I was able to get RPM up to 4-5000, but I could still tell we werent normal power. Drove it hard to heat up the EGTs and came back to check codes. No more stored codes, but the original permanent codes were there, plus two pending/permanent codes. These may have been there originally as well, I'm not sure, as I didnt pull the codes at the start, but anyway, this is the latest:
- P0638 - From what I am reading is the Throttle Valve? just below the EGR valve. I've read some people clean them up, and some people replace them, and some people change the little plastic gears on them.
- P13D6 - from what I can find is a glow plug/Chamber Pressure sensor for Cyl #3. Its not a stored or permanent code, so I'm thinking this could be a misfire/lack of air issue from the other problem.
So on to the question: I'm trying to decide where to go from here given the following.
1) When I was testing the VNT vane actuator, the video says that it should start moving at 2-3" of vac (
) and hit the stop at around 15-18". I think this one is stopping at 12. Granted the cheap vac pump gauge could be off a bit and all good...just trying to decide if I need to pull and replace or re-adjust a bit...I'm leaning towardVNT is probably fine.
2) Yesterday I yanked the battery, airbox, Cooling fans (better access to the Throttle valve), and pipe all the way back to the turbo inlet. I also pulled the sleeve off the charge pipe, and while it seems a bit dirty in there, nothing like others that I've seen in pics.
I figured I would go ahead and drop the TV and check that the butterfly moves smoothly, and maybe even pop the cover and look at the gears. Any other advice on this? Should I pull the VNT Actuator and check the vanes, or just focus on the TV for now since we dont have any VNT codes anymore?
Sorry for how long it is....Thanks for any help offered.