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Old 03-29-2025, 03:09 PM   #16
mkodama
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Join Date: Dec 2016
Drives: 2017 BRZ
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I’m having the same issue with the engine not starting, just stuttering for a few seconds at most when starting. I also track the car, also use an OpenFlash Tablet, and I’m also in NorCal, but the difference is my car is a 2017, I’m at only 44k miles, 63 track days. Zero issues up until I flashed my ECU back to stock tune after an engine rebuild and getting ready for a smog check.

Troubleshooting so far…

Reflashed software:
No difference.

Flushed out 0.5 gallons of old fuel:
No difference.

Checked low-pressure fuel system:
With a mechanical gauge to the low pressure fuel line, 64psi as found, specification 51-73 psi. Good.

Checked high-pressure fuel system:
Using OFT, reading was 204MPa or 29,500psi, and target was 4.03MPa. Specification is 3.00-5.00 MPa or 435 to 725psi. Bad

Checked codes:
P0193, Fuel Rail Pressure Sensor 'A' Circuit High"
P1193, incorrect intake air temperature voltage

Cleared codes:
Codes returns immediately.

Checked high-pressure fuel pressure sensor connector with a multimeter:
pin 1 - sensor 5V supply, measured 5.08V, good.
pin 2 - sensor ground, measured 0V and 0 ohms ground, good.
pin 3 - sensor output, measured 5.08V, bad. Should be 0.5V with 0 pressure and 4.5V max.

Pin 3 stays at 5V until a few seconds after the car turns off the ECU. At that point it measures 8.48 KOhm to ground.

It really seems like the ECU firmware is a bit corrupted and pulled two sensor inputs high. I’m going to continue with the Subaru P0193 troubleshooting guide. Maybe these ECUs can only be flashed so many times?
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