Fast Idle

#1

why does my Saturn idle so fast?

#2

You can adjust the idle. I don’t know much about Saturns, but I would guess there is an adjustment screw somewhere. If you have a service manual, it will probably state what the RPM’s should be at idle and how to adjust it. Your library might even have one.

How long have you had the car? Did you buy it used? An old trick that sham dealers use to mask car problems is to jack up the idle on a car.

I hope for your sake no one fudged the idle to hide something.

#3

Is the CEL on (Check Engine Light)?

#4

Wrong. You cannot adjust the idle by turning a screw. This was true when cars had carburetors, but it’s not true today.

The idle is controlled by the Idle Air Control valve, which is adjusted by the engine control computer. Turning screws will make things worse.

#5

At what engine speed does your Saturn idle?

There could be a restriction somewhere in the throttle mechanism that keeps the idle high, or there could be a problem with the Idle Air Control valve.

#6

I was worked over somewhat when I made a error in regards to how a modern system worked(it was fair criticsim ,I can deal with it)I was told to learn how modern cars work before I post,I won’t be that rough,but Rex that was really bad.

#7

I agree that this is almost always true of modern fuel-injected engines, but it is not necessarily universal.

My '74 Volvo was fuel-injected, and it DID have a manual adjustment for idle speed. Of course, that particular fuel injection system (mechanical C.I.) was a nightmare, but all the same, it did feature manual adjustment of the idle speed.

#8

Yes you are correct,merely being fuel injected does not mean no idle speed adjustment,or even idle mixture adjustment.

with BMW in 83-84 in the 318i with CIS you could adjust idle mixture (true on many CIS cars)you recieved a millivolt signal (read on your multimeter) and adjusted accordingly.

It was the Feds that took away the ability to adjust engine timing ,idle mixture,idle speed,(I think the timing went first)AZ emissions school explained they wanted to remove all possibilites to “fiddle” with the parameters,to many people were getting it wrong.

#9

The electronic throttle bodies don’t even have an IAC valve. The idle is controlled with the throttle plate. The Saturn does not have this feature though:)

Back to the Saturn problem? I would first start looking for vacuum leaks including throttle body gaskets and plenum gasket.