most shops do not know how to do this.
for many reasons.
1: they never seen old cars ever. (nor learned in school)
2: the newer cars , all this is removed, ISC calibration, is fixed now. we have bleed screws from 91 to 98.
so its something you need to learn to do DIY. as most shops would throw parts at it. (at huge costs)
3: the books show using a suzuki meter (duty) that is no longer made./sold or found anywhere..... most were just worn out and dead now.
3b: or a scope. (the most easy of all, and never ever fails to work, see the real thing) a real shop with no scope will never survive.
turn TV screw until the wave form is symmetrical.
3c: or a custom duty meter $$$$ turn screw for 50%
3d: some DMM's can do this, some have a duty meter mode. or the DMM 20vdc range works?,. (try it?)
if the meter 20vdc works, turn the screw until you see 7vdc. (back probing the ISC pins. using needle probes.)
so given all those facts. just try step 1. it's harmless, you can turn it back.. later if need be.. so.... count your turns.
just turn the screw TV stop 89/90 1/4 turn clock wise, adding air (in 91 + cars we open the bleed screw CCW) both ways add air.
what we are doing is centering the command authority of the ISC (new car verbiage ) going to 50% is best.
id do that lacking a duty meter, or try the 20vdc test.
what is happening on your car,is the ISC can not add 120watts of air. needed to run the alternator.
see?
so add some air, and if your added air , works that means your added air was added to the ISC and now it can work with HL on.
total air = ISC + TV air. it's just air, the ECU does fuel like magic.
simple algebra.. if the ISC runs out of steam(air) , add some air.
then the ISC can reach 920 RPM it the regulates there. your's cant reach there.
does that help...
think of a water tank that has 2 hoses.
one add water
and the second drains water
and you are the computer, that yells at the 2 persons on the 2 hoses.
the first hose is draining water this is the ALternator hose.. if you will
then the other hose is the ISC hose. water
the ecu sees the alternator suck out too much water.
so the ECU adds water. but the hose is too small. and fails. hummmmmmm
what to do? so you add one more hose, for adding water (the TV) and adds some with that,
now the ISC hose can do its job, which is keep the water tank 1/2 full at all times...
does that help>? the visuals.????
for many reasons.
1: they never seen old cars ever. (nor learned in school)
2: the newer cars , all this is removed, ISC calibration, is fixed now. we have bleed screws from 91 to 98.
so its something you need to learn to do DIY. as most shops would throw parts at it. (at huge costs)
3: the books show using a suzuki meter (duty) that is no longer made./sold or found anywhere..... most were just worn out and dead now.
3b: or a scope. (the most easy of all, and never ever fails to work, see the real thing) a real shop with no scope will never survive.
turn TV screw until the wave form is symmetrical.
3c: or a custom duty meter $$$$ turn screw for 50%
3d: some DMM's can do this, some have a duty meter mode. or the DMM 20vdc range works?,. (try it?)
if the meter 20vdc works, turn the screw until you see 7vdc. (back probing the ISC pins. using needle probes.)
so given all those facts. just try step 1. it's harmless, you can turn it back.. later if need be.. so.... count your turns.
just turn the screw TV stop 89/90 1/4 turn clock wise, adding air (in 91 + cars we open the bleed screw CCW) both ways add air.
what we are doing is centering the command authority of the ISC (new car verbiage ) going to 50% is best.
id do that lacking a duty meter, or try the 20vdc test.
what is happening on your car,is the ISC can not add 120watts of air. needed to run the alternator.
see?
so add some air, and if your added air , works that means your added air was added to the ISC and now it can work with HL on.
total air = ISC + TV air. it's just air, the ECU does fuel like magic.
simple algebra.. if the ISC runs out of steam(air) , add some air.
then the ISC can reach 920 RPM it the regulates there. your's cant reach there.
does that help...
think of a water tank that has 2 hoses.
one add water
and the second drains water
and you are the computer, that yells at the 2 persons on the 2 hoses.
the first hose is draining water this is the ALternator hose.. if you will
then the other hose is the ISC hose. water
the ecu sees the alternator suck out too much water.
so the ECU adds water. but the hose is too small. and fails. hummmmmmm
what to do? so you add one more hose, for adding water (the TV) and adds some with that,
now the ISC hose can do its job, which is keep the water tank 1/2 full at all times...
does that help>? the visuals.????
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