04 Forester won't fire on SECOND start

I've heard the crank angle sensor can get like this when it's starting to fail.

Any trouble codes stored?

Dave

Dave67 has a great reply. Intermittent crank or cam angle sensor.

I'm wondering if you feel moisture is a factor. Either rain/snow or possibly condensation in the engine compartment. Cracked sparkplug wires or coil pack/coils could prevent the car from starting.

How about the air temperature sensor. Could it be sensing a warm start, after your short run and not enriching the mixture for what is really a cold start. Just a thought.

I had a very similar experience with a 96 saturn SL2. The temperature sensor turned out to be the issue. It was my wife's car and it woudl start fine the first time, but if she were runnign errands and tried to start it minutes after she shut it off, it would crank for minutes before finally coaxing it to start. She never had an experience where she tried to start it 1 to 2 hours after shutting it off, only minutes or over night. Over night always worked beautifully.

I have a few theories as to the mechanism behind this, but I don't know how valid they are. I do know for a fact though, that with that car that was the problem. So I'd suggest replacing the temperature sensor and see if that does anything. For the saturn it was a 27 dollar part.

Good luck, Bill

The software for my OBDII reader has a channel for monitoring the intake air temperature, and coolant temperature (as well as a ton of other stuff). I don't know for sure that the Subaru ECU will output this data, but if it does, that would be an easy way to check the above.

I have the Elmscan tool and software (runs on my laptop), but doubtless any OBDII reader will have similar functionality.

This is probably what you will need to diagnose the problem in any event; throwing new parts at the problem can get expensive, and divine intervention is problematical for most of us ;-)

I need to see what the CEL in my wife's '02 Forry is complaining about, anyway (knock sensor, I'll bet: been there); I'll look to see if the temperature outputs are available while I'm at it, and let you know.

ByeBye! S. Steve Jernigan KG0MB Laboratory Manager Microelectronics Research University of Colorado (719) 262-3101

Hi all, thanks for the input.

Fair warning, I am pretty car-dumb, but to answer questions...

-No, I don't believe there have ever been any trouble codes that showed up with this issue

-Other people have suggested it being a moisture issue, and maybe it still is, but I tend to think no. The things makes it through wind, rain, snow, inside and out, and generally no problems. All of this only happens when it's very cold, so even if it was moisture and perhaps something to do with freeze/thaw somewhere, why would it be fine below freezing (in 20s/high teens) but not when further below freezing? I guess I just don't know what to say there. I never noticed anything to do with moisture as being common to all of the times that problem showed up

Next time it happens, if they still can't figure it out, I may suggest to my mechanic the crank/cam angle sensor and the temperature sensors.

Someone else suggested to me that it could be an intermittently flaky fuel pump relay (owing to cold and it perhaps not making a good physical connection because of size changes in the cold?) Anyone here know anything about that sort of thing?

Thanks again.

I seem to vaguely recall some Outbacks or other models that had a problem- say- backing out of the garage, then not restarting. That is a VERY short trip. Maybe someone will remember that or try asking at