RE: [DML] Re: High Idle only when warm

["Tom Tait" <TTait@xxxxxxxxxx>]

Thanks guys.  

 

David - I'll check the linkage tonight.  I did a minor adjustment on the
stop screw and the microswitch screw yesterday, but I didn't think to
re-adjust the link arm.  I can see how operating temp might affect this
linkage and the throttle plates, but the idle does immediately drop to
normal when I unplug the idle speed motor, so I'm not so sure...

 

Chris - I'm sure I already know what will happen when I unplug the ECU,
Idle will drop to normal.  I've already tried this by unplugging the
idle speed motor(s).  

I know the ECU is telling my idle to run fast, but I'm not sure that
indicates a defective ECU, it may be that the ECU is getting bad data
from a switch or sensor.  

 

Since the problem only happens if the engine is at full temp,  doesn't
that point toward the temp sensor?  When the car is first started and
until it reaches full temp it idles perfectly, all the time.  Once it's
hot the idle will stay high about 20% of the time, and the other 80% of
the time its normal.

 

What are the failure modes for the temp sensor, and their effects?
Besides the throttle microswitch and the temp sensor, are there any
other inputs that affect the logic of the Idle ECU?

 

Tom

 

 

From: dmcnews@xxxxxxxxxxxxxxx [mailto:dmcnews@xxxxxxxxxxxxxxx] On Behalf
Of David Teitelbaum
Sent: Thursday, October 09, 2008 11:02 AM
To: dmcnews@xxxxxxxxxxxxxxx
Subject: [DML] Re: High Idle only when warm

 

David Teitelbaum  >Check out the Quadrant Link. 

Chris > When the idle is high just unplug the ECU. If it drops to normal
you've found the problem.

--- On Thu, 10/9/08, Tom Tait <TTait@xxxxxxxxxx
<mailto:TTait%40BRCWEB.com> > wrote:

From: Tom Tait <TTait@xxxxxxxxxx <mailto:TTait%40BRCWEB.com> >
Subject: [DML] High Idle only when warm
To: dmcnews@xxxxxxxxxxxxxxx <mailto:dmcnews%40yahoogroups.com> 
Date: Thursday, October 9, 2008, 9:39 AM

Hi all. I've got an idle problem that has cropped up. When the engine
is at full temp, and I push in the clutch the idle will occasionally
stay high, sometimes 3000 rpm, sometimes around 1800. This is
repeatable but intermittent. The car operate perfectly when the car is
still warming up.

The throttle cable/spool have returned to fully closed even while the
RPMs are high. Nothing appears to be binding.

The microswitch for throttle-closed is operating properly and properly
adjusted.

The idle speed motor is less than a year old. I swapped on a Volvo idle
speed motor and there was no change.

The temp sensor for the idle speed ECU is about 3 years old. The wire
to this temp sensor had been previously damaged, and it has been
spliced. 

I could swap the ECU with the other car, but I wanted to get input from
here first - I prefer actual troubleshooting to just blindly swapping
parts whenever possible. I suspect that this is related to my temp
sensor or the splice in its wire.

Suggestions as to where to look next would be appreciated.

Tom





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