Intermittent sudden ignition failure

[Charles Packer]

Since having had the engine replaced in her 2001 Forester,
my wife reports the following happens to her almost daily:
in the middle of normal driving, ignition fails
completely and the panel indicator lights come on just as
if she had turned the ignition off with the key. She
has the presence of mind to shift into neutral (it's an
automatic) and restart the engine, then shift back into
drive and continue on her way.

Yet thie past weekend we took a 100-mile trip with
me behind the wheel, through evey conceivable driving
condition from freeway to country gravel road, and
not once did the car misbehave.

In my own 2001 Forester I once had a situation where
corrosion at the bettery terminals was producing
bizarre electrical symptoms, so I cleaned hers
thoroughly. But this hasn't fixed the problem.
What next?

 

[1 Lucky Texan]

Since having had the engine replaced in her 2001 Forester,
my wife reports the following happens to her almost daily:
in the middle of normal driving, ignition fails
completely and the panel indicator lights come on just as
if she had turned the ignition off with the key. She
has the presence of mind to shift into neutral (it's an
automatic) and restart the engine, then shift back into
drive and continue on her way.

Yet thie past weekend we took a 100-mile trip with
me behind the wheel, through evey conceivable driving
condition from freeway to country gravel road, and
not once did the car misbehave.

In my own 2001 Forester I once had a situation where
corrosion at the bettery terminals was producing
bizarre electrical symptoms, so I cleaned hers
thoroughly. But this hasn't fixed the problem.
What next?

My middle daughter had a maxima that would do this occasionally. I
found a Nissan tech on-line that suggested the motor/engine control
relay. I changed it out and her car never stalled again.

have you had the ECU scanned for codes? I think there are some that
may not set the CEL? Anyway, most emmissions sensors that might cause
stalling should trigger the check engine light, so that leaves some
relays or maybe the computer itself? Even if there were some kind of
fuel starvation - I think you'd get misfire codes.

and, similar to your battery issue, I recently had a one-off stall and
some odd codes get set acoupla times on my wife's Outback. But before
I could swap in some sparkplugs that I though could be the problem,
her battery failed and after it was replaced, the codes never
returned. So, yeah - I'd say a weak battery 'could' create some odd
conditions on a car.

 

[Charles Packer]

have you had the ECU scanned for codes? I think there are some that
may not set the CEL? Anyway, most emmissions sensors that might cause
stalling should trigger the check engine light, so that leaves some
relays or maybe the computer itself? Even if there were some kind of
fuel starvation - I think you'd get misfire codes.

Thanks for reminding me about the Check Engine light.
In fact, both mine and my wife's are on now. Since
my Forester runs fine, I just positioned a piece of
black tape so I won't be distracted by the light!
I agree, though, her light could actually be telling us
something meaningful.

 

[Robert L. Wilson]

Charles,
One possibility: Worn ignition lock getting the switch a little off
position. We have had several cars that eventually grew upset at the pounds
of keys on my wife's key chain, compared to my key chain. The symptom there
was that the key was impossible to turn, but if it resulted in the switch
being sort of "in between" positions then vibration could occasionally kill
one of the switched circuits. Just a guess, but you could try, while driving
with your keys, tugging a bit on the key chain in different directions to
see if anything happens.
This could explain why it happens repeatably for your wife, but not for you.
But it would not have any particular connection to the engine replacement.
Bob Wilson