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[Svo] That darn faulty BAP sensor {1}



I few people from the list wanted to know how I found that I had a faulty
BAP sensor so I will tell you about my fun little experience.

The first thing I should tell you is the best way to find if your sensor is
bad is to swap it out for good one.  Heck it's just one connector (and two
screws if it really is bad).  Or to check it with a MAP tester.

Anyways,  I had bought the car knowing that it had a problem. 

The symptoms where like this:
Starting the car when the engine was cold, it would run fine, for the most
part.  Actually sometimes it didn't run right on a coldstart.
Starting the car when the engine was warm, it almost always ran like crap. 
It was like this, when it was first started it be OK until the EEC let the
idle drop from that initial high idle.  Then it started to miss and just
run like crap.  If I would step on the gas it would still run bad and
barely accelerate except sometimes when the turbo spooled up I would get a
swift kick in the *ss.  The odd thing is that when it wouldn't run right I
would quickly switch the ignition from on to off and than back to on with
the motor still turning, somtimes this would "reset" the EEC and it would
run kinda OK.  There would be no miss but there would be this flat spots
when I was under boost.

The first thing I did was to run the self test.  When it was running OK I
would get know codes and while it was missing I would get something about
the idle speed.  I figured this to all to be something in the fuel system
or air metering.  The first thing I went after was the vane meter.  I
checked this with a DMM and noticed resistance of the potentiometer in
there is non-linear output.  The best way I can describe it is being wavy. 
This IS normal, but that not what I thought at the time.  Well that didn't
fix it. So, I went after the fuel pump and replaced it since it was making
lots of noise anyways.  No, that didn't fix the problem, but the fuel pump
was alot quieter.  The fuel pressure regulator I was next.  I thought it
might have problem with heat affecting it.  So, I replaced it.  Of course
that didn't fix it either. I finally decided to pull the MAP from my truck
and put it in place of the one in the SVO.  That fixed it!  It turned out
that my BAP was giving a false reading, not a hard failure.  If it were a
hard failure, the self test would of indicated it.

I hope you find this info useful.

Carl Haines
86 SVO