Jay Roth wrote:

>This summer, the idle is NOT increasing and accelerating from a stop with
>the AC on is hazardously slow. What is this symptomatic of?
>
>
>

Jay, this is usually symptomatic of a failed Idle Stabilizer Valve(ISV)
- cylindrical device mounted on top of the engine with a connector and
wire on the left end as seen from the rear of the van facing forward -
or a failed Idle Stabilizer Control (ISC)which is a black box mounted
just forward of the right rear tail light. Remove the tail light to get
to it.

These work together with the ECU to:
1) boost rpm on a cold start to prevent stalling
2) boost engine rpm with the AC on to prevent stalling. Most noticeable
at stop lights.
3) boost engine rpm when the power steering is racked over to the stops
to prevent power steering pump from stalling the engine.

Failure of either unit will result in the engine stumbling or stalling.

The black box is the weak part of the circuit, and if the cover is
removed burnt parts on the circuit board can often be seen.

Cleaning the ISV thoroughly with brake cleaner will help if the problem
is the ISV is at fault. If the ISC is at fault, not much that can be
done but to replace it.

Both of these items are fairly expensive, but I would recommend new
parts rather than trying to find used parts. Personally, to me it's not
worth fussing over that much. Used parts keep the failure possibilities
somewhat high. They are unknowns.

Good luck.

Regards,

John Rodgers
88 GL Driver