Re: '87 4kq FI problem, FIXED

[James Marriott <marriott@micron.net>]

Robert Myers wrote:
> 
> James,
> 
> Sounds a lot like a vac leak.  Have you looked for leaks?

Today's winner of the "Who's dumber than you" prize is . . . ME.

Yesterday, while sun-roasted and further roasting (under the hood), I
didn't see the obvious disconnect near the battery. Apparently I jarred
the thing ~loose while replacing the valve cover gasket Saturday. It
lasted Sunday for 30 street miles and 11 auto-x runs before giving out
(?).

Poked it back on and the car runs fine, as is the norm I'm accustomed
to. I also cleaned the ISV (idle stabilization valve, shown on Bentley
25.76). This is the goldish-colored metal can, ~4 cm dia x 8 cm length,
near the rear of the intake manifold, on the left side. If you turn the
key on but don't start the engine, it'll make an on-and-off buzzing
sound.

To clean, disconnect both air lines and the 3-pin electrical connector.
Pull the valve out of the rubber mount, and hook the electrics back up.
Turn on the key, without starting the car, and spray some carb cleaner
through both air holes. Place a _disposable_ rag under the draining
hole, as some HEINOUS crud will come out of the valve. FWIW, mine seemed
to operate the same before and after the cleaning; you can see a little
metal piece rotate back and forth through about 15 degrees as the
buzzing comes and goes. I had thought that the idle speed was governed
by the ECU varying the ignition timing. Luis Marquez corrected that by
saying the ISV allows some air--as necessary--to leak by the throttle
plate. More air ==> more fuel ==> more revs. Now I know how it works.

The End
Sorry for the initial WOB and poor troubleshooting,
James

PS Thanks also to Chris Semple, who also said, "No $$$ here, just find
the vacuum leak."