Vehicle speed signal in Typ 89 - now: high idle

[radek at istar.ca]

Thanks guys!  The project is therefore shelved until I get rid of that high idle.

The engine never drops below 1000 rpm, no matter hot hot it is.  No vacuum leaks I would
know of,
both temp. sensors on the coolant neck replaced, O2 sensor nearly new, ISV ok.  Backing up

the stop screw for the accelerator cable does nothing:  the thing stops before hitting the
screw
and the throttle switch clicks nicely.  Any clues where to start troubleshooting?
Thanks for all help.

Radek
88 90Q
91 V8Q 5-sp.

> > So as I can see there are two possibilities:
> >
> > 1. a solder joint somewhere in the instrument cluster is bad; 2. the
> > vehicle speed sensor is bad.
> >
> > Option 1 is no big deal, it does not affect the car's operation.
> > However, option 2 may mean that the ECU is getting wrong information.
> > So the big question here is:  does the speed sensor supply
> > information to the ECU?  Put differently, are those high fuel
> > consumption figures I get while the needle is oscillating true or
> > false?
>
> no.  trip computer information is to be taken with a grain of salt.  the
> trip computer gets info from a few things that matter, but does not
> affect them.  your speedo wire could be cut and dead and your engine
> will run just the same.
>
> > BTW, I took the speed sensor out of the transmission housing, cleaned
> > the electrical contacts (2-pin) and put it back.  No difference.
> > Would anyone know how to test the sensor for output?
>
> I don't, but if anyone tells you privately, please let us all know.
>
> --
> Huw Powell