fun with 306k '88 90Q

[Huw Powell]

Saturday was such a nice day out I decided to finally tackle my sunroof. 
  It briefly worked properly when I got the car, but then got "out of 
sync" at the raise/slide point, then would no longer close properly.  I 
managed to brute force it shut with the motor out and left it at that 
for a couple of winters.

Among other things, I had Chris Semple pull the entire assembly out of 
my faded black car when he bought it for the engine.

In reading how to remove it, the first step is "open sunroof all the 
way" and I kept forgetting that that was not an issue, it was closing 
that was the problem.  Two hours and some tweaking of the motor position 
later, I had a working sunroof.  The black is so faded it actually 
matches my faded grey car.  Reinstalled the headliner, courtesy lights, 
visors, and oh shit handles and everything works except the "door open - 
light on" function (bad timer module?) and my inner visor clips are both 
busted.

Since that was so much fun, on Sunday I decided to try to fix my weird 
tach issue.  For a year or two now, it has usually been reading from 
200-1200 rpms (ie, useless), with occasional episodes of working properly.

First I tried to "test" my spare with a power supply and frequency 
generator, but got nothing, so I just dug in and swapped the "new" one 
in and reinstalled.  Result was no tach at all - and none of the idiot 
lights (except seat belts) worked, neither did the friendly "OK" autocheck.

The Bentley circuit diagram for this part of the cluster is a bit 
unclear - there is a circuit that is shown connecting, in order, the +12 
at the voltage regulator (both gauges work still), +12 at the speedo 
(still works), then the + side of a half dozen warning lights, then a 
split to power the auto check and the tach.

But no sign of where that circuit connected to the outside world.

Also also, that afternoon the car decided to start stalling at idle and 
had a very difficult start condition.  Wonderful.

So I slept on things...

Monday I pulled out my spare cluster circuit board and traced that 
mystery circuit, and indeed it had continuity (< 1 ohm) all the way 
across, and the power source was at the blue connector - the one that 
isn't documented in this section of the diagram.

So out came the one in the car for the fifth time, and lo and behold, 
from source to tach never measured below 40 ohms.  The problem turned 
out to be between the _12 at the VR and the first idiot light.  By 
scraping off the enamel I narrowed it down to a place where the trace 
goes around both sides of a mounting screw and looked a little "funky".

So I drilled a hole and soldered a wire from the speedo +12 terminal to 
a large trace area on the other side of the glitch and reinstalled. 
Yay, idiot lights, tach, and my friendly "OK" were all back!

But it still started hard if at all and stalled at idle.

I was all ready to get basic on the thing and check compression, spark 
(with a timing light), etc., but Carworks was on vacation and Marc 
Swanson was away, and Adam wouldn't have returned my call even if I had 
tried.  So I kept on thinking about it.  Well, one easy thing that could 
do this is a massive air leak between the throttle body and the CIS air 
flap thingie.  So I looked around a few times, finding nothing obvious, 
when on my third search in the lovely 91 dF weather I found that the 
connector for the charcoal canister had popped out of the intake boot. 
Pushed it back in and all is happy again!

Except I do need a pair of visor clips and in another area, the plastic 
clips in the trunk lid that hold the liner in place.

Happy motoring!