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Discussion Starter · #1 ·
Car: 2001 MK4 Golf 1.9 TDI ALH

Problem History: Turbo veins sticking for the past couple of years, boost spikes and car going into Limp Mode in 4th. Have been cleaning with Mr Muscle on and off but was only a temp solution. Took car for good hard run about 2 weeks ago and next day it had no power at all. Started and ran but no turbo.

What I’ve Done: I purchased a new turbo from eBay and fitted it along with new flexible oil feed. Cleaned intake manifold etc. Tried the car after fitting the turbo and still no power.
Unplugged the MAF and the car drove great. Brought a new Bosch MAF and the car drove good for about a week then started to play up again.

New Problem(s): When pulling off in first the car felt like there was no turbo but if I blipped the throttle to around 2K RPM then it accelerated normally again and it behaved fine. But the problem just got worse. Pulling off in first the car would judder and try to stall with white smoke coming out the exhaust, like it was starving of air. Thinking maybe something was sticking like a one way valve or maybe the N75, I replaced all the VAC lines and the N75 but no improvement.

I then began to wonder if the turbo had been factory calibrated and it looks like it’s not.

New Solution(s): I’ve been under the car playing around with the actuator length using a VAC pump. I’ve adjusted the rod length the best I can but I’m not totally happy with my results.

The turbo actuator arm starts moving at 1 In hg and hits the stop at around 13 in hg. I’ve read it should start moving at 3 - 5 in hg and hit the stop at around 18 in hg.

So it’s looking like I’ve also got to adjust the stop screw to get the correct pressures and movement??

For now I’ve just set the rod length so the car doesn’t stall in first anymore and pulls reasonably well but I’m sure it’s not as good as it could be.

I’ve took the car on a couple of runs and logged some data in VCDS. In 3rd gear, pulling from 2K RPM to 4K RPM, my boost gauge will peak at 19psi briefly but settles around 12.5 psi which seems ok but the data I’m seeing in the VCDS looks to me like it’s still not in spec and it doesn’t feel right in 4th and 5th gear.

I’m posting up some data graphs and hopefully someone can offer some advice.

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