[DMCForum] Idle thermistor

["checksix3" <jetjock11@xxxxxxxx>]

Hey Walt, lol...hows about I answer questions from the DML on *this* 
forum? ;)


Rich, it pains me to see you floundering around with such a simple 
probelm. I doubt the idle system is your problem *if* you've already 
set it up as we discussed before.

As far as the idle speed thermistor, forget measuring anything for 
now. All you need to do is short the input on the idle ECU. A short 
will produce 750 rpm, an open will produce a around 2000 rpm. This is 
a common cause of high idle few knew about in the past but most do 
now. (Like Rodney, I get no respect)

Yeah, I know 750 is normal but I don't want to bore you with the 
technical details of what resistance equals what rpm across the range 
or how this thing works on a deeper level. I'll send you a table if 
you'd like. All you need to know for now is a direct short across the 
thermistor will produce 750 rpms (if everything is working right) 
while an open will produce around 2000. (depends how other things are 
set up).

You *can't* troubleshoot the idle system just any old way because 
it's a closed loop system. And it's still running in closed loop even 
if you short the thermistor input. All the thermistor does is offset 
the internal setpoint that I showed you before.

Not only that but there are other closed loops involved that'll 
conspire to goof things up if you don't open the loop. You need to 
disconnect either the PV signal or change the setpoint level for best 
results. That way you can manipulate either and do anything you want. 
I though we already went over all this in the past? 

Sigh...

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