Turbo Overboost CEL light at high speeds only

Hey guys,

Pretty new here but have lurked around for information in the past to help solve my glow plug issues and most of my overboost issues.

2000 Golf, with 140,000 on it.

When I first got the car, I had overboost problems but it has always been a lack of power never a stalling situation but If I am behind another tdi on the parkway and we both hit the pedal the other car will out distance me quickly at any speeds.

I have cleaned the intake manifold and the egr valve but did not touch the cooler. The manifold was very very clogged up and the egr was pretty clogged as well. I looked at the turbo the veins were not clogged up and it all looked clean hopefully I can rule that one out. After I did this I seen a slight boost in power but nothing crazy though I never expected the car to push me into my seat either.

Now I will not trip my CEL light and I can hear my turbo spooling up fine but if I drive over 75 mph I will trip my CEL and when I read it, it is always the overboost code. It goes away after I turn the car off, and drive around town for a day. The turbo still sounds fine when the light is on and I dont feel any power loss but it just annoys the hell out of me that it will trip on like that.

Any ideas I read through the faq for the overboost but did not come away with a fix for my particular issue. I am not opposed to removing the egr and the cooler but for simplicity I wouldnt mind having the car functioning correctly with them because I would rather just go through regular inspection without problems because this is my high mpg commuter car more then anything else.

Thanks for all the help this is a great forum

Andrew

This might be symptomatic of a failing N75 valve or maladjusted turbo actuator rod. You've stated the turbo vanes looked clean but didn't mention if they moved freely so get a vacuum pump with a vacuum gauge and test the turbo actuator with the engine off. The actuator rod should start moving by 3"Hg and hit maximum travel by 18"Hg. Please report your findings to help others with this same problem

I have similar problem. Above 75mph I normally go limp mode with overboost code. Cycling ignition gives me my power and turbo back. I haven't been able to figure out why. It works fine all other scenarios. I'm assuming sticky vanes.

jagster936 said:

I have similar problem. Above 75mph I normally go limp mode with overboost code. Cycling ignition gives me my power and turbo back. I haven't been able to figure out why. It works fine all other scenarios. I'm assuming sticky vanes.

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Same here...This issue is really annoying and somewhat dangerous. I normally hit overboost on a small climb going to 100km/h and the car barely moves.

Haha yea I think I need new turbo but don't wanna mess with as it's fine if I just slow down