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

["Elvis Nocita" <elvisnocita@xxxxxx>]

Tom, you for sure have the common problem that I 
have seen on many Deloreans.

first of all - the idle motor has no such thing 
as a fall back function !
pulling the connector there is no such thing as 
"going back to normal " !!!

if this happens only when hot, I bet it's the 
idle switch not being pushed correctly anymore
or - and this is tricky - the butterflies do not 
close completely anymore due to worn bearing !

try to push the lever of the butterflies to fully 
close when this happens. the engine must be running 
as the vacuum of the engine does help to this problem !

I had this very same problem on two cars  that I 
worked on. an easy solution is to bend the spring 
a bit to put more force on the butterflies to get 
back to the closed position.

Regards,

Elvis & 6548



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



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