5kcsq low boost-help?

[Bernard Littau]

[snip]
> Boost reads between 0.0 and 0.3
> bar at idle, and maxes out at 1.0 bar 95% of the time, occasionaly bumping
> to 1.1. Reading through the paperwork, there is a note from a mechanic
that
> the auxiliary water pump is disconnected. I'm wondering if the problem is
> due to an under-cooled oil-coked turbo which does not spin freely, due to
> the engine being in "limp home" mode because of a faulty sensor, or if
> perhaps the boost readout is somehow wrong. Any BTDT or ways to rule out
> culprits here?

Hi John,

A boost of 0.3 at idle is fine.  0.0 would be interesting, I only get 0.0 at
idle when I am going rapidly down hill doing engine braking.

0.3 - 0.4 at idle is quite normal if you are sitting still.

A good test of the boost sensor is what does it read when the ignition is
on, but before the car is started or cranked.  The boost sensor should be a
baromoeter, and should usually read 0.9 bar.  If you are significantly above
sea level, it might read lower.  Check your local barmometric pressure 1000
milli-bars equals 1.0 bar.

Boost of 1.0 or 1.1 at full throttle, as long as you have no check engine
light warnings, is most likely due to a leak.  There are poeple who can tell
you the most likely places to look, but for a systematic and complete
approach, best to check out Scott Mockery's very fine web site:
http://www.sjmautotechnik.com/boost.html#chklist

The information here can be a bit overwhelming.  You should, by using
Scott's site, be able to figure out how to "check codes" on your MC-1 10V,
and then work through the process of making sure your engine is up to
generating normal stock boost.

Scott's site is sometimes not intuitive to navigate.  The link above kind of
drops you into the middle of things.  Here is the path I took:
http://www.sjmautotechnik.com/
click on the Troubleshooting Tips, this brings you to:
http://www.sjmautotechnik.com/trouble.html
click on ABC's of Running High Boost 10V Turbo Engines, this brings you to:
http://www.sjmautotechnik.com/boost.html
click on Boost Problem Checklist, this is where my very first link took you.

Have fun exploring around!  Scott's site is full of good information, with
pictures and diagrams.

Don't be shy about asking questions on stuff in Scott's site.

More than likely your turbo is fine.  Mine is still fine at 250000 miles on
the engine and turbo.  You should fix the aux. water pump.  The MC-1 does
not have a limp home per se, but will throw codes and activate the check
engine light if there is a problem.

Best,

Bernard Littau
Woodinville, WA
'88 5ktq