[Author Prev][Author Next][Thread Prev][Thread Next][Author Index][Thread Index]

MC engine overboosting...


I guess things never get better. I've now found out what it feels like
when one "hits the brick wall" as the fuel pump cuts out.

My previous messages state something about the boost readings  being
too high for my location at altitude and the ECU boost settings.
On my trip yesterday the car showed 1.6 bar on the electronic gauge,
but the car did not feel like it was pushing  that much.

I decided to take the car to the local VW guy during lunch today.
I was pottering along  at about 90km/h and decided to see if the
boost gauge still shows the high pressure readings. So I gave a bit
more  gas, not too much, just about half throttle position. The car
picked up speed slowly (no immense accelleration). I was watching the
boost gauge, 120km/h came and the gauge hit 1.6 bar (the car, 200t
with auto tranny, is set to 1.4 in the ECU with about 1.6 bar
overboost feature) and  all of a sudden the cut-out happened and I
felt what the brick wall thing is like. I was shocked. I thought I'd
killed something in the car. I then just drove over to the VW mechanics

The thing  about all of this is that I was not  pushing the car hard.
This happened in 3rd gear, revs about 3000-34000 RPM, speed about
120km/h, throttle about half on the pedal. About a month ago, before
I went to Cape Town, the max I ever  got out of the reading for  boost
was 1.1 bar and then I had the pedal flat with the kickdown engaged
and the car was flying forward. Now half throttle, 3rd gear, 120km/h
sets off the overboost cutout and I don't know why.

What do I check here? How do I check the pressure metering switch?
How do I check that the readings the computer is getting is correct?
How do I check  for a stuck wastegate diaphragm that might be causing
the problem? Would a huge hole in the exhaust contribute in any way?
I also have a large whistling sound happening from the left side of
the car and from the centre when I'm really gunning it (the  car is
RHD), could this be a split vacuum line running to the computer? That
could explain the slight lurching I was feeling all the time as I was
driving yesterday.

The boost really builds up fast on the gauge, but not much feel for it
in the motion of the car.

"a thousand miles from here, there is another person smiling"
1990 Turbo (200T)
name   : gerard van vught
tel    : +27-57-912 2658 (w) / 082 923 9609 (cell)
url    : http://www.acenet.co.za/homepages/gerard/
e-mail : gerard@poboxes.com  / han.solo@galaxycorp.com
         gerard@acenet.co.za / van_vught@frg.issi.co.za