Setting BISS and ISC Range

According to the Vfaq www.vfaq.com/mods/BISS-1G.html

You want the ISC in the middle of it's range, while adjusting the BISS for optimal setting (Our idle should be 800 RPMs). But what exactly is the middle of it's range? If you log it, I think it goes anywhere from 0-100+. Does anybody have hard evidence on where it should properly be set @ idle with a logger using MMCD? Should it be set closer to 0 or 50? The logger shows a value of zero while just idling. But if you ground out the ignition timing adjustment plug and the diagnostic plug, only then it will give you a number 0-100? Kinda weird

 

[iLLeffeKt vr-4]

ISC should be 30 or very close to it.

 

cool. Can anyone confirm this? Should it read 30 with the diagnostic + timing plugs grounded or just regularly at idle?

 

I read something on 3SI.org last night that said @ idle your ISC value should be around 10.
Mine is 10 @ 800 RPMs at idle. But if you drive around, it goes anywhere from 20-60+.

 

[atc250r]

Quoting Besso:
Should it read 30 with the diagnostic + timing plugs grounded or just regularly at idle?



I think it will lock itself at whatever Mitsu programmed it to when you ground those two (maybe its 30, I don't know). Once you ground them and set the idle to spec with the BISS your ISC reading after that will change with temperature, electrical load, AC load, PS load, and probably a bunch of other things.

John

 

yea, thats what I thought too. But when I grounded the pins out, it would still fluctuate from 0-11+ /ubbthreads/images/graemlins/dunno.gif depending on how you adjusted the BISS

 

[atc250r]

Really. I don't know.

 

Scott just sent me this. Sheds some light on the situation

 

I always liked to see mine around 10, with the engine fully warmed up, no fans or accessories running. That way I knew I wasn't going to get idle surge from the ISC not being able to lower the idle enough, but I also knew I had a lot of range above that if needed to raise the idle. Remember, the ISC is just an air bypass, so "0" means its not bypassing any air past the throttle blades.

 

Jeff, that is exactly how i set it. I believe what the vfaq meant by centered, is inbetween the 5-15 tolerance (5+15/2=10). John was right though, when you do ground the pins the ISC is set to 9. I just didn't notice it the first time