Aussie 07 Impreza Engine Stalls on Highway

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. :)

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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;

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) IT'S THEKEY IMMOBILIZER COMMUNICATION. Seems to me that could very well stopthe car! I dunno. Maybe someone else knows more. Carl

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1 Lucky Texan

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:

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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

Reply to
S

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.

Reply to
1 Lucky Texan

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