Idle Speed Control (ISC)

[Lextreme II]

I wonder how would the car run if we delete this ISC unit. If we can delete it what type of electric bypass would take to trick the signal for the ECU. Would a resistor will work? From the diagrams below, we can relocate the ISC for those supercharger guys. Relocate or remote ISC will work I think. What do you think?

 

[jibby]

I do not the answer to the above post question, but I do have a related concern I would like addressed, does anyone know if you need to mess with the ISC when installing headers? I know this is slightly off the subject but being that I needed a EGR blocker I am a little concerned about this ISC now.

 

[cribbj]

It's a stepper motor so it would probably take more than a simple resistor to bypass it. Some with AEM's on Supras just remove it, block off its port, and use the old school way of adjusting the idle screws on the TB to get the idle they want. Idle adjustments with the AEM can be a real PITA....

Don't know if the OEM OBDI ECU would throw a code or not if it were disconnected, but that's easy enough to find out.

 

[mycarhasposessedme]

Here's a pic of a block off plate I made from a scrap of billet.

 

[SCV8]

All of the cars I have seen with the EGR disabled have then run lean through the progression/ off-idle.
I have tried to remove the IAC on another vehicle, and could not get a decent idle without it. I figured it's a pretty integrated part of the system.

 

[KDog]

You can adjust the idle the old way by using the bypass screws on the throttle body. Stock they are not open enough and will probably stall you car. Adjust them until you get a decent idle.
Not sure what effect on the ECU it would have if any. You would be better off relocating the ISCV rather than deleting it.
You can't make a dummy load with resistors.

 

[200sx-v8]

I am going to block of the isc, and install some kind of manual valve. Have done this on other engines with good results. I have never needed any electronic idle control.

Only problem I can see with doing this is cold start. But it's possible to use a cold start bypass valve from an other engine.

 

[Toysrme]

I'd just let the stock computer handle it 'cause it's going to do a lot better job than other things. Put the ISC supply pre-compressor with a one way check valve so boost can't flow back out.

 

[mycarhasposessedme]

The only reason I have blocked mine off is my engine management doesn't have stepper motor control.
I'll see how it goes, if its a problem I'll install a pwm type valve from another engine.
Cheers