Aussie 07 Impreza Engine Stalls on Highway

[blank]

Thanks to all who have shown interest in my problem. As I said, I have sent
it in for a checkup, and included a number of the suggestions you guys made
in a note I left in the car for the mechanic. So they checked it out as you
suggested. Here is there report:

System Test and Diag Tech: 113
Engine stalls on highway.
Checked vehicle operation for stalling on highway. Checked DTC found P1574
present but not related to stalling issue. Carried out checks as per
customer request, checked plug leads and ignition coil connectors, all okay.
Carried out diagnostic check on select monitor, all okay. Checked wiring
connections at main harness connecter under bonnet and under dash, all okay.
Road tested vehicle and checked all data, all okay. Was unable to reproduce
fault at the time of testing. Have sent FPRS to Subaru regarding this issue.

Inspection Cost: $647.26

So it looks like I'm up shit creek. Does anyone know what P1574 refers to?

(Oh, I'm just joking about the inspection cost--there was no charge.

 

[1 Lucky Texan]

Thanks to all who have shown interest in my problem.  As I said, I havesent
it in for a checkup, and included a number of the suggestions you guys made
in a note I left in the car for the mechanic.  So they checked it out as you
suggested.  Here is there report:

System Test and Diag   Tech: 113
Engine stalls on highway.
Checked vehicle operation for stalling on highway. Checked DTC found P1574
present but not related to stalling issue.  Carried out checks as per
customer request, checked plug leads and ignition coil connectors, all okay.
Carried out diagnostic check on select monitor, all okay.  Checked wiring
connections at main harness connecter under bonnet and under dash, all okay.
Road tested vehicle and checked all data, all okay.  Was unable to reproduce
fault at the time of testing. Have sent FPRS to Subaru regarding this issue.

Inspection Cost:  $647.26

So it looks like I'm up shit creek.  Does anyone know what P1574 refersto?

(Oh, I'm just joking about the inspection cost--there was no charge.  

That code appears to be manufacturer specific, for some cars it's a
bad brake light. BUT (yes, it's a big but) for Subaru (according to
this link anyway; http://www.aboutautomobile.com/DTC/P1574 ) IT'S THE
KEY IMMOBILIZER COMMUNICATION. Seems to me that could very well stop
the car! I dunno. Maybe someone else knows more.

Carl

 

[S]

Hi Blank!

So it looks like I'm up shit creek. Does anyone know what P1574 refers to?

I had to do some research, but:

P1574 EBTCM System- Stop Lamp Switch Circuit High Voltage

EBTCM is a GM thing; Electronic Brake Traction Control Module. How
that applies to your Soobie, I couldn't say. Anybody?

Sadly, I can't think of much else you can do to diagnose the problem.
Intermittent problems are every technicians nightmare; it's
considerably easier to fix a problem once you know what is causing it.
But then Murphy's Law states very clearly that the glitch will never
occur while you are watching. What to do.

You might try connecting a data logger to the OBDII port while you're
driving. You can get scanners and software that run on a laptop fairly
inexpensively, check out ScanTool.net.

What to look for? Internal combustion needs three things to work; an
air/fuel mix at somewhere near the proper ratio (~14:1), adequate
compression, and ignition at something like the correct time, say
10-30 degrees before TDC.

I think we can eliminate compression from the equation; it's purely
mechanical, and either is or isn't happening. Watch for unusual
numbers in the MAP sensor, fuel trim and O2 sensor channels occurring
just prior to a stall. Engine RPM and timing advance might show
abnormalities as well. You'll have to educate yourself on modern
engine control systems before this info will be particularly useful.
Try wikipedia to start off:

http://en.wikipedia.org/wiki/Fuel_injection


This all takes a lot of time, patience, and a fair bit of luck, but
_if_ you can catch a glitch, you have a starting point, anyway. Or you
can do as I suggested earlier and go over the wiring harness with a
fine-tooth comb, all it takes is time, patience, and luck . . . ;-)

Now you can begin to see why the dealership isn't real anxious to jump
right on your problem.

Best of luck with this.

ByeBye! S.



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

 

[1 Lucky Texan]

That code appears to be manufacturer specific, for some cars it's a
bad brake light. BUT (yes, it's a big but) for Subaru (according to
this link anyway;http://www.aboutautomobile.com/DTC/P1574) IT'S THE
KEY IMMOBILIZER COMMUNICATION.  Seems to me that could very well stop
the car! I dunno. Maybe someone else knows more.

Carl

I also read there can be problems with 2 or more immobilizer-chip keys
on the same key ring. Try making sure your wife has no other such car
key near the ignition. Also, you could try swapping keys with her if
you never encounter the problem. Though the problem certainly could
be in the steering column or wherever the transceiver is for that
security feature.