EFI question- what about the ISV?????

[Brett Dikeman]

At 10:31 AM -0700 5/20/02, Jason wrote:

>Do you adjust idle based on mixture/use the screw by
>the throttle body?

Nope.  That screw(on most audis) is never supposed to be adjusted,
it's a factory-set item and is used to adjust clearances on the
throttle after it is assembled(I think.)  Idle is a very dynamic
thing, especially on engines like the I5 where there is little
torque/power at idle, and little rotational mass(unlike a nice big
chebby V8)...temperature, accessory load, A/C...all affect idle.

>   If you do use the ISV, where does
>it get it's inputs from since you don't have CIS
>anymore?

Most EFI controllers send out a PWM(pulse width modulated) signal to
drive the ISV.  The controller varies the duty cycle in response to
load on the engine; RPM drops, ECU commands more air via the ISV.

HTH,
B
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