90tq problems continue

[Huw Powell]

> 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/