Re: [DML] idle revisited

["Jerry Harry" <jlharry@xxxx>]

Well,
Im not one of the guru's on this list, however I have spent time on
this idle circuit.
I think if your idle speed motor is working ( Buzzses with the key on,
engine off ) and your idle tends upward you have a vacuum ( inlet air) leak.
The leak prevents the idle motor from being in total control of the
available air to the engine at idle.
Where the air is getting in can sometimes be located with an accelerate
like carburetor cleaner. Just a shot here and there to find the spot that
outside air is getting into the intake manifold. When the accelerate gets
in, the engine RPM will go up for a moment. I would start at the back left
side were the idle control motor hose goes into the intake manifold. (
O'ring missing) Then at all the openning into the intake even the ones you
think are closed.
The diafram in the ac/heater switch could be open or any one of the
vacumn lines under the dash could be open, broken, etc. So to get them all
out of the question I would remove the large rubber line coming out of the
intake manifold on the rider side and plug the manifold. This way you know
the leak is not forward in the cars compartment.
I'm surte you have tried most of this but it might help someone.
Your's in the Hobby
Jerry Harry
Vin #4890



From: "Louie Golden" <louie@xxxx>
To: <dmcnews@xxxxxxxxxxxxxxx>
Sent: Wednesday, December 24, 2003 2:06 PM
Subject: [DML] idle revisited


> Hey group,
>
> I've done some more fiddling around with my car's idle... trying to figure
out what the deal is. Initially I thought the cable was somehow not getting
enough tension to return the throttle arm to the microswitch, but it looks
like that is no longer the issue. The throttle can return the arm to close
the microswitch, but the microswitch doesn't make the car idle down every
time like it should. I've lubricated the ever living mess out of every
visable part of the throttle linkage from front to back on the car for
reference. When the car is cold, it idles perfectly (well, as perfectly as a
PRV CAN idle...), but as the car warms up, something suddenly happens and
the car's idle jumps to 1500 and stays. I've watched it in the driveway as
this happens, so since the throttle arm isn't moving, this tells me it's
something in the automatic idle system. Several months ago I could blip the
throttle, and the car would *sometimes* idle down to where it should, but
this is no longer the c!
> ase. The idle is getting progressively higher. After being driven, it now
wants to idle at about 2000 rpms.
>
> Over the last few days I've played around with some things. First I just
unplugged the idle speed motor to see what happens. The idle will drop about
200 rpms sometimes, but will jump up other times when I try this, but when I
plug it back in the car idles down to 800 rpms. So for an experiment, I
tried switching out the idle speed motor with one from my old DeLorean. This
changed nothing with the idle situation. So let me see if I understand how
the idle system works- the idle speed motor is electronically controlled by
the idle speed ECU. The idle speed motor controls the throttle plates by
vacuum. For reference, I also put on a new CPR over the weekend, and I also
know the O2 sensor is bad because the car hunts when it is very very cold.
So I've deduced that my idle speed ECU is the problem after all of this. Am
I correct? Is there any further ways to test it? I really don't want to
chunk down that kind of money if I don't have to, but the idle situation is
getting so ann!
> oying that I don't want to drive it any more. I would be grateful for any
additional viewpoints or suggestions. Thanks!
>
> Louie Golden
> VIN 5252
> NC plates "88 MPH"
>
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