Re: Idle speed sensor

["David Teitelbaum" <jtrealty@xxxx>]

You should not have had to modify the circuit to force the idle up 200
rpm. A properly functioning idle circuit will hold the idle at the
correct idle rpm with varying loads like the A/C and the alternator.
The main reason the thermistor raises the idle is to make the car warm
up faster, the idle circuit can keep the cold engine running even at
the lower speed but for the EPA there is a maximum warm-up cycle time.
David Teitelbaum
vin 10757



--- In dmcnews@xxxxxxxxxxxxxxx, "checksix3" <jetjock11@xxxx> wrote:
> Mark, a thermistor is not a simple contact closure. Thermistors are
> resistors that change their resistance with temperature, either 
> increasing or decreasing in resistance with a change in temp. (They 
> come in two flavors called positive or negative coefficent.) The idle 
> thermistor in the Delorean is used to alter the idle speed setpoint 
> depending on coolant temp. On my car a custom circuit is used to 
> exploit this function so as to increase the idle 200 rpm when I have 
> the headlights or A/C on. 
> 
> This sensor is not on or off like a switch. You can't look for a 
> contact closure, you need to measure it with an ohmmeter while you 
> change it's temperature. The spec escapes me at the moment but if it 
> changes resistance (somewhere below the 10K ohm range as I recall) as 
> you heat and cool it, then the odds are it's probably working. Use 
> only an ohmmeter, if you pull to much current through it (by using a 
> large 12 volt test light for example) you could damage it.