Idle Speed Control (ISC) Bypass

[Lextreme II]

Anyone what would happen to the car if i disconnect the tube from the intake to the ISC? What will happen for the following changes:

1. Plug up the intake pipe and ISC inlet
2. Plug up the intake pipe and use a breather valve for the ISC inlet
3. Complete delete of ISC

Anyone know how will the engine behave with the above combinations.

 

[Lambo]

Hi David, Have a read of this it might help get a better handle on what will happen if you loose the valve, on a mitzi its not good when the valve stops working, the idle up when on full lock on the power steer does not happen and they usually stall right in the middle of a 3 point turn on a busy road, not good been there .http://www.autoshop101.com/forms/h60.pdf

Best Regards
Lambo

 

[cribbj]

David, on standalone MAP based ECU's there's no problem with putting a breather type filter on the ISC inlet, and eliminating that pipe to the intake, but with the MAF systems you'll not be metering that air if you take it upstream of the MAF, so you'll have a lean idle.

Some Supra owners with AEM's have eliminated their ISC systems and just run their cars on the TB stop screws. The ISC in the AEM software can be a real bear to setup and get both good stability and fast response.

The downside of running the idle on the TB stop screws is what Lambo pointed out, plus the dip in revs whenever the A/C comes on, or when your big electric fans come on, etc.

 

[Lextreme II]

I think in my setup with FI the ISC take lots of abuse and its easily malfunction. I need to find an alternative way to solve this.

 

[BARRY]

you can remove it, by pluging up everything

or

put a breather filter at the intake side of the valve. i've done this myself on my 20v motor when converting to open throttles.