mofologic

does the isv control or have direct or indirect effect on anything other than idle speed. i cleaned mine and still got idle speeds up to 2k. disconnected it and set idle by screw on throttle linkage and idle is between 600 - 1000 with some wandering, but no high idles yet. curious if it has any effect on acceleration - i still got the intermittent stumbles.
tia
joseph

CARSNPLANES

You said you played with the idle screw, was the screw screwed in all the way with the Isv connected properly?
Don't forget, proper config is idle screw in all the way (closed) , ISV connected, all vacuum hoses and crancase breather hoses clamped, no leaks. Maybe your throttle switch is inop? ECU needs to know it's at idle through the throttle switch, which will trigger the ISV to regulate the proper idle air for 800-900 idle speed. That's why the aux idle screw must be turned IN all the way. The ISV can't have any other air coming in while it's trying to do the whole job by itself.

tonyj

on the throttle body.
If so, that is not the idle screw. Like CARSNPLANES said that is the fine adjustment to be sure that the throttle linkage operates the closed throttle switch that tells the ISV controller to operated the ISV.
It should be set so that when the throttle is releases it 'just' switches on the ISV (OHM out connectors on top of throttle body).
If you are using this for idle the ISV will never operates and the idle will not be stable or correct.

CARSNPLANES

Thank you Tony for backing me up, but I think you are half correct. The throttle plate will/should close to activate the idle switch regardless of the screw's mechanical position. It doesn't mechanicaly hold off the throttle plate from bottoming. The screw has a tapered tip that closes off air from a hollow "vein" inside of the intake manifold that runs from the throttle opening to the fitting for the ISV tubes.
The throttle switch can be adjusted (see elongated adjustment holes on the screw hold downs)to make sure the throttle plate is activating the switch correctly. A definite "click" should be heard when the plate is almost bottomed. The click should be heard again when the throttle is just "cracked" or coming away from idle.
But yes, screw should be all the way in for proper operation.

mofologic

i adjusted the screw at the external linkage rods, nothing at the tb or im. doesn't sound like the same one from reading your posts (at least to me). thanks again...........
joseph

CARSNPLANES

I'm trying to picture what screw you are talking about?

mofologic

screw is thru throttle linkage bracket and is backed by nut - functions more or less as a stop for the triangular bracket the throttle cable and cruise rod attach to.

CARSNPLANES

Yeah, I think you may be adjusting the throttle cable housing adjusting nut. That more or less adjusts the "throw" of the cable. You make adjustments there to make sure you have "full" throttle and still allow the throttle plate to come home to idle and activate the idle switch. You want to make sure the throttle plate isn't held open by any adjustment, and when home, is COMPLETELY closed. If not,that will allow air through the plate in addition to air metered through the ISV and gives you a high, erratic idle.