Manual Idle vs Automatic Idle

["content22207" <brobertson@xxxx>]

Fully agree that properly functioning automatic idle system is
preferable to manifold screws. Mine was improperly malfunctioning.
Sometimes would stick fully open. Sometimes would stick fully closed
(that's when I discovered what those screws are for). Replacement
motor and ECU exceeds $500. Screws are already in place. Guess which
route I chose...

Fast idle is accomplished with an "auxiliary air valve". Extremely
common on other cars contemporary to DeLorean. In fact, mine is used
from a BMW ($5 on eBay).

Originally thought I would also have winter and summer idle speed
settings, just as I do on my Lincoln re-carbs (Edelbrock wants $80 for
an A/C solenoid!), but find that simply leaving aux air valve open
works just as well. Really only need in city driving.

In your defense, while Volvo 260 used manual idle speed circuit, a
1990 760 I recently popped hood on had an idle speed motor that looked
just like DeLo, in exactly the same place.

I think it's important to understand manual idle circuit for diagnosis
if nothing else. How else to rule out idle speed motor as a potential
problem?

My experience has been that rocket science doesn't age well. On my
Lincolns, for example, automatic headlight ativators and dimmers are
usually DOA. Is a challenge just to keep cruise controls properly
functioning. Would argue is unrealistic to expect ALL DeLo ECU's and
idle speed motors / Lamda valves to function today as they did 22
years ago. Some do -- more power to them. But an owner shouldn't
assume he or she will be so lucky. Running problems may well be
attributable to a failed system. Mine was (and I don't even have Lamda).

Bill Robertson
#5939

>--- In dmcnews@xxxxxxxxxxxxxxx, "David Teitelbaum" <jtrealty@xxxx> wrote:
> When you disable the idle speed motor you give up a lot. The motor
> will no longer run faster when cold and if you turn on the A/C or run
> a lot of accessories like headlights and rear defogger the ISM cannot
> keep the idle speed stable. Under high loads at idle the ISM will keep
> the idle at 775 rpm. The fixed metering screws cannot adjust to
> varying loads. In addition in some states you are not supposed to
> tamper with anything that can affect the emissions. Some states do
> check these things. For your own sake and that of a future owner it is
> usually best to keep the car as origional as you can. It is often
> harder to make changes than to try to stay origional.
> David Teitelbaum
> vin 10757
> 
> 
> --- In dmcnews@xxxxxxxxxxxxxxx, "content22207" <brobertson@xxxx> wrote:
> > Mention this to list with trepidation because it usually ignites flame
> > war, but IMHO is important:
> > 
> > At same time JZD was messing around with idle speed motors, Volvo just
> > used brass screws already built into PRV to set idle. Low tech, yes,
> > but less subject to problems. I think every owner should know how to
> > use in case automatic idle system fails or needs diagnosis, if