1987 on Idle Control Valve, how it works

[Mrmerlin]

Well I took apart the Frozen ICV and this is how it works,
it looks to be made so there are not any parts touching inside like the brushes that rubbed on the armatures of the earlier 85/86 versions.
It appears to made to work like 2 magnets repelling each other to generate its twisting ,
it also appears that if it should get wet then it can easily rust inside and thus freeze up like this unit did.
The setting tensioner spring is placed inside the white connector cover this will pretension the armature, and electrical current will run the armature open.

So this unit appears to be a long life unit and if its kept dry and free of carbon then it should last indefinitely ,

That said there isnt any way to know if its corroded internally unless its cut open or holes are drilled in it.

I ordered a new part from Autozone and will see if its a Bosch part,
the part cost was 132.00 with free shipping to the house.


FWIW dont wash the engine with water this is what you cant see when things get wet

[MainePorsche]

Stan
As the ISV as non dissectable, what do you consider the best way to clean it when one has it out for cleaning and bench testing ?

[Mrmerlin]

as far as cleaning it,
the only part that will get dirty is the vane a little bit of spray cleaner should do the trick,
NOTE I would keep the inlet/outlet as the lowest point so the cleaner doesnt run the dirt into the motor section.
NOTE the cleaner may also remove any lubricant on the shaft thus increasing the stiction of the vane so some sort of spray lube might be in order.

the only other thing I could suggest is to use a pick to see how easily the shaft/vane moves,
if the vane is sticky then it might be time for a new part as it could be corroded internally .
Drilling a small hole in the end might let this become obvious if its corroded or if the spray cleaner used runs out with orange deposits

[Landseer]

Stan,
Do you think this ISV could/should be utilized when replacing an 85/6?

[Mrmerlin]

no they are different ,
the old 85/86 has a 3 prong connector,
the 87 on has a two prong connector ,

the older style is commanded open and closed,

the new style is commanded open only then it is spring closed

[Scheuer]

My car has been having idle issues recently so I suspected the isv, although I replace it 10k miles ago (albeit 7 years).

To test, I disconnected the hose at the Y on the drivers side manifold, and started the car. It runs great!! I assume that this points to the isv, but am curious why the cars runs so well with this disconnected