Please advise... Low power at startup

[DeanOusterhout]

When I first start the car, 2000 Golf TDI, as I begin to drive the engine doesn't seem to go... and then after a couple seconds, it jerks with power and begins to respond normally.

It is as if it wasn't getting fuel and then all of a sudden began to.

This just started a few days ago after I rebuilt the exhaust system with a Passenger Performance 2.5 downpipe, High flow Cat, and AERO resonator for the muffler.

I am not saying that it is the exhaust.. just that that was the last change made.

Any thoughts?

Dean

 

[mojogoes]

How old is your filter plus valve on top of the filter.....and now that its much colder are you using any winter additive/s

 

[The Shootist]

Unplug the MAF and see id it goes away. My Beetle gave the same symptom last summer.

 

[Gothmolly]

Sounds like sticky turbo vanes. Can you log boost on VAG-COM ? Try manually moving the actuator, or run the mythical VAG-COM N75 tester.

 

[DeanOusterhout]

Mojoes, I noticed this morning it was above freezing and there was just a touch of hesitation around 2000 RPM's, almost nothing. I am not using additives and now that you mention cold... it didn't start until it was dropping below freezing.

I have a CAT filter... I need to look in my book to see how many miles, but I am pretty sure it was earlier this year. I don't think I have ever changed the T.

Gothmolly, how do you log boost with VAG-COM? I have the tool but never used it for that.

Thanks all... I appreciate the feedback. The help folks give here is fabulous.

Dean

 

[The Shootist]

Did you try unplugging the MAF?

When mine went accelleration was poor, then at about 2200 rpm it hesitated like hitting a wall. Push the go pedal harder and it would jump and run fine untill the next restart.

 

[Gothmolly]

If you go to the measuring blocks, you want block 011. It logs indicated, requested boost, and I think mass air flow. At the bottom you can log the data, and then plot it out in OpenOffice or something - when you get on the pedal, you might see a big spike in requested boost, but no corresponding rise in real boost pressure.

To check if the actuator is sticking, best do it with a hot motor. Unplug the vacuum line leading to the actuator from the N75 valve to release any vaccuum. Then, wet a shop rag, and wrap it around your thumb. Feel down onto the hot exhaust manifold for where the actuator connects to the turbo, and then push down on it with your thumb. You will hear the water in the shop rag boiling, don't be alarmed. The spring in the actuator will resist the effort of pushing on it, but it should move somewhat, 1/4 to 1/2 inch.

If this seems good, you might need to remove the actuator from the turbo, then work the little lever on the turbo where it connects. Minus the spring force of the actuator itself, you can usually move the lever on the turbo an inch or so.

I had similar issues as yours, along with weird boost issues while driving, and I found that about 1/2way through the normal travel of the turbo lever gizmo, it was sticking, both on open and close, which caused me to have over or under boost issues. Once I worked the turbo lever free of whatever crud was binding it up, things ran better.

I found that you have to do it on a hot motor, since whatever gunk is stuck in there seems to cool/harden/bind when the motor is cold.

 

[DeanOusterhout]

Shootst, did you wind up replacing the MAF? I have already replaced it once, about 100K ago.

 

[Gothmolly]

No the MAF wasn't the issue, it was that the turbo actuator/vanes got sort of gunked at about the 1/2 way part, so sometimes when it called for boost it would stick at 1/2 way, and then sometimes STAY stuck at 1/2 when the ECU no longer called for it.

 

[The Shootist]

Yep, I replaced it. Fixed it right away.

The MAF's on these cars are prone to problems, and the ECU won't always throw a trouble code.

Anytime you have a power problem this quickest thing to do is check the MAF by unplugging it.