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Re: '87 TQW idle problem?
> very well otherwise. I checked the idle stabilization solenoid, it
> appears to
> be working OK and is clean. The problem persists exactly as before if
> the idle stabilizer is disconnected. Opening the oil filler cap
> stalls the engine. No obvious holes/tears in turbo induction hoses.
> The 900 RPM-to-2KRP-back-to-900 RPM cycle takes about 3 seconds.
> A/C on or off makes no difference.
I wouldn't expect a leak to the atmosphere because that would screw up the
mixture and make it difficult to run at all. It sounds like the problem is
that intake air is getting around the throttle body somehow ... you checked
the idle stabilization solenoid to no effect. I was surprised to hear that
disconnecting the solenoid made no difference ... my '88 nearly dies when
the solenoid is disconnected. You also said that the symptom is the same
independent of the A/C ... try pinching off the lines to the A/C air bypass
solenoid to see if that doesn't help. The only other thing that comes to
mind is the idle speed adjustment screw on the throttle body itself. Has it
come loose or fallen out completely? Other than that I would look at all of
the connections on the intake manifold side of the throttle body (including
the vacuum lines that come off the back of the manifold) and test by pinch-
ing off any hoses.
I don't think that a fuel system problem would cause the symptoms that you're
seeing. If the air metering plate was not returning properly or the control
pressure regulator was malfunctioning it would simply screw up the mixture ...
no more air would be allowed into the engine.
Best of luck on your quest!