90tq problems continue

[ed armstrong]

Huw,

Thanks for responding, actually I made some
troubleshoot blunders and determined last weekend that
the CIS computer is OK.

This morning I believe I may have found my culprit. My
car is only pulling a few inches of vacuum at idle.
There is bad vacuum plumbing or a big time leak
somewhere.

I'll probably have another post is a few days.
Unfortunately a haven't had the time to work
consistently for a few hours on the car..

--- Huw Powell <human747 at attbi.com> wrote:
>
> > The DPR current is 0 ma all the time, regardless
> of
> > cold or warm start. That and the code 4444 is why
> I
> > think the CIS fuel computer is shot.
>
> Sounds about right...
>
> > Havent given to much thought to the pontentiomter
> yet
> > but I'll eventually check it too. The 5 V I refer
> to
> > is for the DPR signal, definitely not the
> > potentiometer.
>
> Have you carefully checked the intake manifold
> ground wires for the CIS3
> computer?  I would assume they are good based on
> your voltage
> measurements, except perhaps you were measuring to
> the battery ground
> and not the block.
>
> > The air plate test I described comes straight out
> of
> > the Probst book. You have to hold the throttle
> open
> > for this. On cold start you should see a quick
> > increase in DPR current signaling momentary
> enrichment
> > (I guess this assumes the potentiometer is working
> > correctly too).
>
> OK, that's cool, but althought he Probst book is a
> fabulous read and
> resource, I'm not sure I would use it to diagnose a
> particular car - the
> Bentley factory shop manual is going to be more
> precise in its
> troubleshooting procedures.  I'm not saying that
> this test is not valid,
> just that the Probst book is a bit more general.
>
> > I replaced the small coolant sensor with a new one
> a
> > while ago. I believe this what the computer uses.
> The
> > larger one directly beneath it (both are on the
> water
> > inlet to head) is what is used for the instrument
> > cluster readings according the Bentley.
>
> You're right.
>
> --
> Huw Powell
>
> http://www.humanspeakers.com/
>
> http://www.humanthoughts.org/


=====
-ed

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