[supergoat]

Hi.

[120308 - Charging pressure control, plausibility pressure too low]

My car just started throwing this code at me. It disappears when the car is turned off. Does not throw an engine light or have any pending OBD codes. Just the "Drivetrain malfunction" warning.

First off I do not have any logs, I understand that may hinder some help but that's where I'm currently at.

In 1st and 2nd gears the car runs strong, feels like full power. No issues. In 3rd gear and above I can go 1/2 throttle with boost and all is well. Above 1/2 throttle in 3rd gear and above the car will usually throw this code at me now. The car otherwise runs super smooth, no noises or other issues. If you keep the throttle under 1/2 you would never know there was an issue.

I have checked my ER chargepipe and it is tight. Connections to the intercooler and TB are solid and the coupler is also tight and free of damage.

All surrounding hoses also seem to be tight with no visual tears or damage. I have also replaced the Pressure Convertor with a known good one that I had to see if that was the case but it wasn't. I also replace the vac line from the convertor to the valve cover with no luck.

Turbo to IC hose appears solid. Connections are tight and I felt all around but found no damage. Can't visually see all of it through.

I'm planning to replace the line from the pressure convertor to the wastegate this weekend to see if that's the issue. I plan to replace the crank case breather hose while I'm in there but don't think that would cause a boost issue, correct me if I'm wrong.

My real question is, how can I rule out or in if the OEM DV is failing without a visual inspection. I ask because my car is an XDrive and getting the DV out will be a pain in the D so I want to rule out everything else prior to making that my plan of attack.

Also, any other places to check before I start having to dig deep? I also ordered new TIC and CP gaskets and will replace them just for piece of mind as they are super easy to do.

Any tips or guidance would be appreciated.

[thejeremyman9]

Visual/physical inspection of TIC-IC-CP connections isnt a substitute for a proper pressure test to verify no leaks. That's what i would do before throwing any parts at it

[Orion4]

Concur. Conduct pressure check/smoke check. All it takes is a very small leak that may be invisible to eye.

[supergoat]

Appreciate it. New gaskets where the IC mates to the TIC and charge pipe seem to have held off the code for a few days now. If it pops back up I'll pressure test.

[supergoat]

Update: The code came back and now I could reliably make it trigger. First and second gears would pull hard but when holding a higher gear under boost, for example on an on-ramp, it would trigger. I did not have to be full throttle. Light throttle, but enough to build boost would do it if held longer than a few seconds.

This told me it *may* be a boost leak but a wastegate issue is more probable so I rechecked the vac lines on the pressure convertor. Seemed fine visually, wastegate held vacuum fine. So I turned my attention to the small vac line from the valve cover to the pressure convertor. It was not damaged but came off rather easily. It still had a small grip but not much of one. It was becoming hard but still a bit pliable so I wasn't convinced it was the issue.

Either way I replaced it with a high temp silicone line I had while I was in there. Turns out that did it. Full boost restored in higher gears and I can hold it as long as I want. I'm guessing it would leak under vacuum after a few seconds. Like I said it didn't just slip off when I pulled it off but it wasn't hard to remove either. I have been putting the car through it's paces these last two days to make sure. Hasn't missed a beat and power is better and more reliable than previously.