Charge Control Circuit Output Test

I just used VCDS to test my turbo boost control system by using the output tests function.

I'm not sure if the results are normal or not.

The engine speed increased from idle to about 1400 RPM, and then the controller started exercising the VNT actuator.

I could hear the turbo spool up and down, but the charge pressure reading only varied from about 989mbar to a high of 1060mbar.

The manifold pressure reading when the car isn't running is 1020mbar.

It seems like there's almost no boost being produced during the output test. Maybe this is normal, maybe it isn't.

I do get the impression that there is a little too much lag when pulling away from a stop. It has been this way ever since my local VW dealer got their mitts on it to do the EGR cooler recall (twice since they botched it the first time).

So, is 1060mbar way too low during the boost "on" portion of the output test? It's barely any boost at all, so it doesn't seem right to me.

I've done that test but I don't recall the engine speed changing. Anyways, you won't make any boost because there isn't a load on the engine. If you just blip the throttle up to 3-4000 rpms in neutral you won't see hardly any boost.

Actually, I don't think I was in output tests. It was basic settings, known diagnostic outputs, or something similar to that. There were only two choices, which were charge control circuit test or an EGR system test.

Here's an old graph showing the boost lag I'm talking about. The overall control is pretty good, it just takes the turbo a couple seconds to "get with the program" and produce the required boost.



Click to enlarge