Turbo going 3psi above specified when WOT

SaulHeno

Member
Joined
Jun 8, 2021
Location
Ireland
TDI
Golf 6 1.6
Hey all, I've used these forums in the past, never posted much. I have been on and off with TDi for a while. MK6 Golf TDi was my first car, and now I'm back to a 2008 B6 Passat Sport BKP TDi. I don't think you guys got these in the states, but you did get the engine (I know about the oiling issues, mine should be gear driven. If I keep it long enough, it'll get an ALH pump conversion).

Anyways, It had a nasty limp mode problem when I got it, if you floor it in third, eventually (around 3200rpm) it slams itself into limp mode and needs a key cycle to clear, then its fine. It does the same if you push a higher gear too hard as well. It also whistles really bad from the left front when on power. Mechanic said it was an intercooler pipe leaking on the left (your drivers) side. I'm imagining this is after the MAF? I've attached a highlight of the pipe I think the mechanic meant here.


I datalogged it with OBDEleven, I'm attaching screenshots of charts for the WOT run in third, limp kicked it right as specified jumped up iirc. This was a pull from 1400~ RPM until it limped somewhere around 3200-3500


Its pretty consistently about 3-4psi above specified as you can see.

So, is this sticky turbo vanes? That was my belief but I guess I want some other input before I go attempting a clean. Or could this be mostly from the (assumingly) post-MAF boost leak in the intercooler pipe.

I appreciate the input, thanks!
 

JETaah

Vendor , w/Business number
Joined
Jan 18, 2001
Location
mi 48836
TDI
96 B4V, 1999.5 jettaIV,2005 BEW Beetle
You may be way above that 3spi mark. It looks like you topped out the MAP sensor and it can't read higher.
I would check it with a mechanical gauge on the charged air pipe. Until then back off! You could cause serious damage.
 

SaulHeno

Member
Joined
Jun 8, 2021
Location
Ireland
TDI
Golf 6 1.6
You may be way above that 3spi mark. It looks like you topped out the MAP sensor and it can't read higher.
I would check it with a mechanical gauge on the charged air pipe. Until then back off! You could cause serious damage.
Yeah I noticed this yesterday, way way WAY too flat to be a real reading. I've learned when to back off knowing when its about to overboost, so I'm ok for now driving until i sort it.

Im cleaning the turbo this weekend hopefully, I'm hoping its just sticky vanes or a stuck actuator. Ill be logging it after to see if its any better, fingers crossed
 

JETaah

Vendor , w/Business number
Joined
Jan 18, 2001
Location
mi 48836
TDI
96 B4V, 1999.5 jettaIV,2005 BEW Beetle
Check the n75 vacuum vent line to the air box, too. If it is clogged it can't release the vacuum.
I am guessing this is the same design on your car if you have a VNT set up.
 
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