block the ISC?

[chucky]

has anyone blocked the isc? what would happen if i do that mod, would i still be able to adjust the idle speed only with the BISS screw?
i'm getting tired of the idle surge and no matter what i change it still happens. i thought of designing a manual ISC like a screw type of thing. has anyone done that before?
thank you guys.

 

[chucky]

any info guys please, seems strange to be the first one to try.give me a clue.

 

[chucky]

ok guys, i'll try to build a manual ISC and see what happens. time to block the fiav too.
i'll let you all know how it goes.

 

[GVTalon]

I’m not positive on all the mechanics of an ISC but I’ll offer you my guess. The ISC is an electronically controlled stepper type motor. During the engines heating up and usage cycle, the stepper motor moves the plunger in and out of the throttle bodies cavity allowing a certain amount of air through ports past the TB plate thus allowing the engine to maintain a proper idle in a given heat cycle. I’ve also read that the ISC will compensate for minor mechanical problems the engine is experiencing in order to maintain a good or slightly higher idle.

So would a “mechanical ISC” work? You may be able to adjust one so it will idle well at one certain temperature, but it won’t work through a heat cycle without constant adjustment.

 

[chucky]

i was thinking about the old carburator concept, and it didn't seem to matter years ago. the ideal thing would be to be able to tune from inside the car.
does anybody know for sure what role the isc plays after the throttle is open?
cause if it only adjusts idle speed, there shouldn't be any problem once the throttle is open.

 

[turboholic]

Originally posted by chucky
i was thinking about the old carburator concept, and it didn't seem to matter years ago. the ideal thing would be to be able to tune from inside the car.
does anybody know for sure what role the isc plays after the throttle is open?

-There're 3 idle control component within the throttle body: the BISS; the ISC & the fast idle valve.

-If your idle surge problem is cause by a malfunctioning ISC, then you
will be constancely adjusting your new mechanical idle adjuster. I would you find out if the ISC is bad(replace), block the coolant going into the throttle body to see if it help.

-I did hook up a pot to adjust air/fuel ratio in the cockpit before, but that was on my Mitsu Mirage with a working ISC. by fooling the ECU on coolant temperature, adjustable range 700-1600 rpm.

-May be a MBC type bicycle cable to the BISS as an adjuster.