Intermittent idle cut-out

[Arryn Milne]

Hi Matt,
I'm having the same trouble, and as a point of reference, new items on my 
car are the throttle switch, deceleration fuel cutoff valve (there's a TSB 
about them failing open), ISV (Idle Stabilization Valve). Problem still 
exists.

Have you tried this:
http://www.sjmautotechnik.com/ecuf.html#out1
It may help.  Maybe.

The last thing electrical in the system I can think of is the idle temp 
sensor, which, if I'm reading Bentley right, is in the same area as the 
multifunction switch:
SJM has an illustration, but reading the Bentley, I thought it was sharing 
a connector on the after-run sensor.  SJM is usually pretty accurate though:
http://www.sjmautotechnik.com/cooling.html#gauge
I was going to run some leads to a multimeter inside the car so I could 
watch what happened as the car warmed up.  I was hoping to see it either 
jump to 0 ohms or infinite.  Bentley has a chart of expected resistances.

Would you let me know what you find?  I'm frying bigger fish at the moment, 
I suspect my fuel pump died (car just quit and won't start), but once I'm 
up and running, I'll let you know if I find anything out.

Later,
Arryn


At 08:45 AM 7/23/01 -0700, you wrote:
>I posted a message a couple weeks ago regarding an
>issue I was having with an idle that would go all
>whacky after a short while of driving.
>
>The car "fixed" itself, and I have probably driven
>3000 miles since I last had the problem.  Well, it
>started again last Friday.
>
>Description:  After ~15 minutes of driving in warm
>weather (say 80F+), the car will not idle without
>holding the accelerator down a fair bit.  My shifts
>get jerky as the revs drop quickly when this happens,
>and the car frequently dies if I cost in neutral for
>any length of time.  It has idled a couple times at
>~300 RPM, but not often.  The car will pull fine at
>1.8 bar before and after this happens.
>
>Parts that are new and/or OK: cap/rotor, wires, FP
>relay, fuel pump, fuel pump check valve, intake system
>(no large vacuum leaks), MM hose etc.
>
>I really think it is something electrical that goes
>flaky after a certain time spent at temperature.  I
>doubt that it is spark as it will idle as normal; it
>just needs additional throttle.  My decel fuel shutoff
>is disabled so that's not it.
>
>So what is electrical that would affect idle fuel
>mixuture?  Frequency valve I guess?  Maybe the power
>to it is getting cut somehow and it won't idle.  Would
>this cause my problems?  Any other thoughts?
>
>Thanks in advance,
>
>Matt.
>'86 5kt
>'73 911E
>
>
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