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