You can pinch off/ block the hose from the ISV to the intake and that will bypass the ISV.

 

Clark's Garage has a good explanation of disabling the ISV via the diagnostic port. Look in the section about setting the idle.

Even then, though, if the ISV has failed open, I can't imagine it would provide enough air to allow the car to rev to 6,000 rpms.

 

That is with no load and the hose to the idle controller can supply a good deal of air to the intake.

 

IMHO he needs to plug the hose for the ISV, not go through disabling it, as if it has failed open (had one local do it) it WILL allow plenty of air to get past the throttle body.. he would know it was leanning out if he installed his Zietronix..

IMHO his chips are running it rich at idle, so not so lean with the extra air getting in..

I highly suspect ISV, but forgot to mention on the phone last night..

E, also check the clamp orientation on the hard pipes where the boot connects to the throttle body, had another car local to me, he not only had / has a bad ISV, but his throttle was getting stuck on the clamp and getting held open...

 

I also had a leak at the intake to head gasket. Double stupid mistake, put the gasket in the wrong orientation (they fit several ways, only one is right) and didn't torque the bolt correctly. Big leak resulted.

 

I'll check Brian. I know I got the gaskets in right. The #1 gasket goes upside down. The rest fit normally. I torqued the bolts to specs with a torque wrench. I should be good there.

 

Welp. it's definitely the ISV. I clamped the hose to the intake mani and viola! I probably also need to reset the TPS. I'll look into that Monday. For now my idle is at about 1400 to 1600, which is of course high, and GAS GUZZLING! but works fine. The car sounds FANTASTIC!
Watch for an upcoming thread thanking a bunch of really fuc<ing outstanding people, including some parts vendors and fellow listers. As always, you guys are what this obsession is all about! What a fantastic community!

 

I bought a second ICV thinking mine was bad when it was really installed backwards so I have an extra laying around if you want it. It has ~108k miles on it, came off my '88S. PM me if you're interested.

 

So, for those of you who electrically bypassed the ISV, did you jumper it from A to B or from B to C?...and why?
LR has it jumped from B to C. Clarks has it jumped from A to B.

 

sending pm.

 

Just checked, Clarks has a jumper between B and C:
For '85½ and newer models defeat the operation of the idle stabilizer by installing the jumper between terminals B and C of the diagnostic plug (see diagram).


From the DME_KLR test plan.