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No Boost W/Kickdown

Hi Al,

Sounds to me like the car is loosing a lot of pressure somewhere. I had
similar symptoms,the car was dead at low revs and only started boosting
over 4k rpm. When it boosted the max I could get was 1.4 bar. (Running 2
bar normally).

My problem was a very rare one I believe, the waste gate was not closed
properly, and only under some help from the ECU (WOT condition, manifold
pressure into , waste gate), would it close.

I checked for leaks, temp. sensors, WGFV,  ECU wiring, timing   etc.
etc. as suggested by SJM, could not find anything.

The test that worked for me was to bypass the WGFV and feed manifold
pressure straight onto the waste gate (the input that normally comes
from the WGFV). By doing this the whole setup is controlled by pressure.
The manifold pressure will now close the WG for you if it is OK. Mine
still had the same problem, which eliminated all electrical and other

Drive it carefully and watch the boost gauge (ECU will cut engine when
you exceed preset boost so it is quite safe, doesn't feel to nice
though). If it still does not boost low down, your problem could be the
same as mine.

Fix: A friend opened the waste gate, dismantled it and cleaned out the
deposits. Checked diaphragm.  Fitted  a bolt through the back of the WG
as suggested by SJM, and tightened the WG spring. Problem sorted out,
works like a charm.

Hope that helps

Renier Meyer
89 200T Durban South Africa
84 200.

Al wrote:

Friends, I'm still working my way through this - I have a new
idle/WOT switch installed and adjusted as the Bentley specifies on
the wife's 1990 200, (automatic) but it's still running weak.  It's
usually won't provide any boost over 1.0 bar unless I kick it down
into a lower gear.  Then the boost comes on with the
kickdown...but all I need is the boost.  Dunno what the deal is.

I'm currently studying SJM's very helpful reference page but would
be interested in any helpful comments.  I will try pulling codes
again, but the last time I tried to do so I couldn't produce any
codes at all (and this after pulling the dash and installing a lamp
just for that purpose...) leaving me high and dry.   Rats.

TIA for any help.
Al Powell
1958 Fiat 1200 Spyder "Transformabile"
1983 Datsun 280ZXT
1990 Audi 200