low power

[Konstantin Bogach]

Hi listers.

One of my 200q '89 has low power output.  Injectors new, fuel pressures
are in spec, boost develops to 1.4bar at WOT, 1.2bar was seen when it
had bad trottle switch which makes me believe that additional 0.2 bar
are coming through WGFV.  No vacuume leaks, intake air temp sensor is
good.  I check almost everything.  Except exhaust back pressure and bad
valves and leaks in cylinders (which I don't know how to check).
I have 2 questions:
1. What back pressure is considered good and acceptable?
2. What else I can check to narrow down  the problem debugging?

Thank you very much.

Konstantin Bogach
200q '89 (week)
200qa '89

P.S.  I have another question for 200 avant owneres: where is rear wiper
relay? It is not in there where Bentley depicts it. That slot is empty
(auxilary relay panel)