Re: idle revisited

["content22207" <brobertson@xxxx>]

Idle speed motor BYPASSES the throttle plates. Has the same effect as
variably cracking them open with lower throttle plate screw (which is
another way to manually set idle speed -- just like an old fashioned
carburetor -- but without benefit of balancing air to each cylinder bank).

Don't you remember that #10115 ran manual idle circuit? Why not
experiment with the same on #5252?

For others' info: it is very easy to switch back and forth between
manual idle and CIS. Once manual circuit is tuned, difference is one
hose vs one screw.

I've re-written manual procedure in Forum files section (IDLE.TXT) for
better general consumption (earlier version was nothing more than text
from a private eMail).

Bill Robertson
#5939

>--- In dmcnews@xxxxxxxxxxxxxxx, Louie Golden <louie@xxxx> wrote:
> 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 case. 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 annoying 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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