[DML] Re: Yet another Idle question

["Harold McElraft" <hmcelraft@xxxxxxx>]

I assume that it was idling fine at one point?

I would suggest you check to make sure the idle speed circuit is 
working - cold and hot. I'm not sure what Martin is saying but, the 
idle speed circuit IS activated by the idle speed micro switch. The 
best description of the idle speed control system is on page 77 of 
the Technical Information Manual - a partial wiring diagram is also 
on page 80.

The micro switches do go bad from time-to-time. Linkages can change 
position slightly when the engine is warmed up causing the idle speed 
circuit turn off - but wear usually causes the idle system to come on 
too soon causing the engine to die when you let off the gas - so 
unless you messed around with the linkage or adjustments of the idle 
screws, that is not the first thing I would check. You may have a 
vacuum leak at the distributor solenoid or vacuum advance that 
appears when the thermal vacuum control valve warms up and turns on 
the vacuum to the solenoid.

Methodical diagnosis of the function of the idle system activation 
components is what is what I would do first.

Harold McElraft - 3354



--- In dmcnews@xxxxxxxxxxxxxxx, "Bill Koenig" <dmc06976@...> wrote:
>
> I'm having some trouble diagnosing a problem with 6976.  It starts 
up 
> and runs like a champ, however when the engine warms up, the idle 
> gradually increases to the point that it doesn't go below ~1500rpm.
> 
> Now I've heard people say its the thermistor, but I been in the 
valley 
> of my car and I don't want to return unless I am sure that is the 
> problem.  I wanted to test the thermistor (and possibly the whole 
idle 
> system).  Is it true that I should measure the resistance of the #9 
& 
> #11 wires coming off the ECU when the engine is cold/hot?  I read 
> someplace else that on a cold engine, resistance should be around 
10K 
> ohms, and it should drop considerably after the engine is warm (if 
the 
> thermistor is working).  Except I couldn't get a reading connecting 
my 
> voltmeter to those two wires, so instead I was measuring resistance 
at 
> the #9 and #11 pins on the ECU (which I realize now was a stupid 
> mistake).  So I'm wondering - does anyone have any guidance to 
offer?  
> Or perhaps an alternate means of testing my idle control system?
> 
> Thanks,
> Bill
> (and VIN06976!)
>




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