Re: Low boost problems -- at wits end -- HELP!

[Gisli Ottarsson <gisli@master.adams.com>]

>>>>> On Wed, 07 Jul 1999 19:41:23 -0700, Mike Posner said:

  MP>  I assume you werre not getting proper boost prior to new Mich. man.

This is correct.  Before Mich I was seeing 1.0 tops.

  MP> What is your vacuum reading at idle? 

0.4 bar.

  MP> Do you have any exhaust leaks? 

Nothing audible, visible or smellable.

  MP> ... ie cracked manifold, though they usually self seal when they
  MP> get hot.  

Condition persists at all engine temperatures.  Stable 1.1 bar max.

  MP> Check for hose leaks on the pressure side from intercooler to
  MP> throttle body. also look for cracks in the intercooler pipes.

OK, thanks.

  MP> Also dont count on the digital pressure guage to be
  MP> accurate. see what your reading is with another guage.  

Will do, although two things suggest that this is accurate:

 a) WOT without Mich man pruduces 1.0

 b) Applying 20 in Hg vacuum to manifold produces ca. 0.3 as
    proposed by Mockry.

  MP> Is the vehicle at operating temperature?  

I await a new radiator resistor pack so I have had to be cautious.
However, my testing has run the gamut of engine temperatures.  Max
boost is always the same 1.1 and seems to be regulated at this
pressure.

  MP> Hows your Cat?  If its clogged, it will impair boost ...

I am planning a visit to an exhaust shop to measure back-pressure.

  MP> ... as will a clogged air fillter, fuel filter

Good point.  New air filter tomorrow.  Fuel filter is new.

  MP> ie everything needs to be clear going in and coming out.  Kind
  MP> of like the digestive system.  Its an ongoing problem with
  MP> boost, there are so many things that can affect it

Thanks, Mike.  Keep the quality advice coming, all.

Gisli


-- 
Gisli Ottarsson, PhD                     
Mechanical Dynamics Inc.            gisli@adams.com    
2301 Commonwealth Blvd.             Tel: 1-734-913-2550
Ann Arbor, Michigan 48105           Fax: 1-734-994-6418