What should happen with ISC unplugged?

[joeym4130]

This is a quick ?. What should my talon idle at with the isc totally unplugged?? I just unplugged it before starting so its at whatever position it goes to when you turn the key to off. My idle goes down a little but not much. What should happen is there a definite answer?

 

[Lordpaxin]

there is no definate answer, considering the possibility of so many things that affect idle, your just not letting the ecu try to correct idle anymore

I have idle surge, I pulled every sensor, TPS< ISC< idle switch<everything, and no effect at all.

do a leak test.
and jump over to www.vfaq.com and dsm.org and read their idle issue pages.

but tehy helped me none atall.

 

[skater182]

so is it safe to run the car with the isc unplugged? that seemed to solve my idle surge problum

 

[JessesTalon]

Originally posted by skater182
so is it safe to run the car with the isc unplugged? that seemed to solve my idle surge problum

I have run without a ICS for over a month, doesnt hurt anything, fixed my idle alot, but I still get some crappy surge every once in a while.... (now that I garage my car it is ALOT less though...?

 

[skater182]

what does your car idle at with it unpluged? mine will ide no higher then 1500 no lower then 1000

 

[joeym4130]

with mine unplugged, i can get it low enough to stall or run up to like 2500 all thru the BISS screw.

 

[joeym4130]

Wait i just had a thought....
So, I have been trying to figure out the idle problem. Did everything leak test, faqs, etc. Now i was gonna try a whole new TB, just cause i can get one cheap. But since i can get it low enough to stall by disabling the ISC, wouldnt my problem be there??? The ISC tests good...maybe its bad even tho the coils check out, im sure thats possible.

 

[BOBS90TURBO]

Did you check the BISS idle screw itself or the BISS o-ring , a bad gasket will cause air to get in and surge.
Just to let you know I am in the same boat as lordpaxin, I have replaced every possible thing that controlls idle and still have surge, I am trying to learn to live with it.:thumbdown

 

[joeym4130]

Well the o-ring looks good, but wouldnt the BISS be ok since i can control the idle w/ the ISC unplugged?? I can lower the idle to 900 w/o the ISC but when i plug it in the idle goes to somewhere around 2500! Maybe I'll figure it out someday haha...but until then i just drive around w/ it.

 

[joeym4130]

anyone else agree plz? that the ISC is the only culprit since i can idle it down when its unplugged?

 

[Lordpaxin]

The isc doesnt just randomly set idle.
The ECU is telling the ISC "hey, i need more air"
if your ISC has the correct Ohmage on the pins. Look elsewhere.

The most common reason for HIgh Idle is An Air leak. and the engine sucks in more air that the MAF sees.

When unplugging the ISC you are merley Foiling the ECU's attempt to correct a problem with idle conditions

 

[joeym4130]

yeah i may be wrong here, but if it WAS an air leak, wouldnt i still have an idle problem when the ISC is unplugged?? Cause If adjusting the BISS can put me in control enough to completely stall the motor wouldnt that mean i have no air leaks?? Like if it was an air leak, wouldnt there be a point when trying to stall it where the leak would just keep letting air in and the motor wouldnt stall?
oh and i have heard of ISCs whose coils are reading good, but their pintle wont move right w/ voltage.

 

[joeym4130]

Ok, if anyone has input it would be mucho appreciated!! This is adding onto the previous discovery i had made.... Ok, so like Paxin suggested, it might be an air leak which i had thought it had been all along. BUT! If i start the motor cold, i cannot adjust at all w the BISS screw, with the screw in all the way it will stay at like 2000RPM.... After I let it warm up to operating temp, then i can make the car stall w/ the BISS, but if i bring it down to around 900 it just runs rough so maybe a tiny air leak? i dunno....

 

[BOBS90TURBO]

If you are idleing rough when your at low idle I will bet you have an intake leak, I was doing the same thing untill last week. Have you sprayed stp carb cleaner around the intake manifold gasket and t-body etc... Mine reved up alittle every time I sprayed around the manifold gasket area. Since I replaced it my car runs great, smooth as new.

Also have you adjusted your TPS, mine was not closing correct and it was screwing with my idle on my old gst, it has to be perfect, I have also had throttle cables to tight before.