[urq] intermittent ignition cutout

[DGraber460 at aol.com]

In a message dated 3/22/2005 10:28:09 P.M. Mountain Standard Time,  
ekellock at adelphia.net writes:

Had hoped that my IC and burnt wire adventures would yield some change  to 
the cutout.
Still chasing the wire, so won't know for sure until its  resolved.

But, I've gotten a pretty clear fix on the behavior of the  cutout, purely 
subjectively of
course.  The cutout does appear to be  temperature sensitive to some degree, 
though not
summer heat temp type  sensitivity.

The car starts up beautifully and runs nicely as it warms,  but as it does, 
the cutout
manifests.  It's almost always momentary  and as long as it's not a idle 
(even sometimes if
it is), the cutout is  short enough that the engine will catch and continue 
running.

I bought  some resistors to put in place of a couple of sensors so as to fake 
out the  ecu
and either eliminate or isolate the issue.  In looking at the tdc  and rpm 
sensors, there
is a 3rd wire for ground.  I haven't quite  sorted out how to rig that to 
fake out the ecu.

I have swapped in a  spare ignition module (thanks Dennis!), however the 
behavior  was
unaffected.

The cutout is definitely electrical in nature.   The tach drops to zero and I 
think even
the fuel pump quits, though I'm not  positive about that.  I replaced the 
ignition switch
and the fuel pump  relay about a year or 2 ago while diagnosing a no-start 
situation.

I've  been wondering about the load reduction relay.  Mine appears to be  
original.  I do
hear a click when the ignition cuts out.  Haven't  been able to isolate it 
yet though.

Just a recap and thinking out  loud.  I'm open to your thoughts.

Ed





I'm purely  shooting from the hip here, but my impression is that the only 
true ignition cut  off these cars have is the over-boost pressure sensor in the 
ECU, and oil  pressure loss? The pressure transducers do go bad once in a 
while from what  I hear. The load reduction relay will not cut ignition- only 
lights and  accessories, and the fuel pump cut off will not make the tach drop to  
0.
I would try  to pinch off the tube going to the ECU, eliminating any input to 
the pressure  transducer, and see what happens.
The flywheel  sensors are the only other "usual suspect" in my thoughts. If 
the ECU can't  "see" TDC, it will cut spark. Why that would be heat related is 
strange but  could happen I suppose. The sensors on the head will only make it 
run rich or  lean, but won't shut it down.
Your car has  taken on the early recalcitrant behavior mine showed early on. 
Defying logic and  being somewhat of a bitch.
Have you swapped distributors with a known good unit yet?
 
Dennis
Denver