Engine cranking but not running after rebuild.
 

Update 2024-04-04: found the cause! Crank timing was off 360 degrees.

Please help if you can. I’m getting a little desperate because shops are declining to help.

Everything was looking great during my engine rebuild, fine tuning oil clearance and adjusting valve shims, etc. up until I went to crank the engine and it doesn’t run. I get at most a rough idle for a few seconds..

Vehicle: 2017 Subaru BRZ 44,000 miles.

Additional details: prior to the rebuild, I was frequently flashing between E85 and stock tune with an OpenFlash Tablet. 63 trackdays. The rebuild of the engine is with 13.5:1 pistons and stronger rods but all else stock. I added 10 gallons of 100 octane unleaded to a tank that had maybe 0.5 gallon of E85.

Troubleshooting so far…

Reflashed software between OEM, E85 OFT, and 93AKI OFT tunes with no difference other than OEM gives live diagnostic readings of 204.00MPa fuel rail pressure while the OFT tunes give 26MPa. ECU target was 4.00MPa. Specification is 3.00-5.00 MPa or 435 to 725psi. Bad

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 codes:
P0193, Fuel Rail Pressure Sensor Circuit High Input
P1193, Fuel Rail Pressure Sensor "B" Circuit High Input
Cleared codes and they return with enough cranking.

Checked high-pressure fuel pressure sensor connector with a multimeter:
ECM check, engine on, not running:
A36-19 (VC) to A36-29 (E1): 5.01V good
A34-7 (PR) to A36-29 (E1): 4.09V bad
A34-9 to A36-29 (E1): 0.53V bad

Harness open check:
A34-7 (PR) - C46-1 (VOUT2) 0.9ohms good
A34-9 - C46-3 (VOUT1) 0.8ohms good
A36-29 (E1) - C46-2 (GND) 0.9ohms good
A36-19 (VC) - C46-4 (VC) 0.9ohms good

Harnesses short check:
A34-7 (PR) or C46-1 (VOUT2) - body ground OL good
A34-9 or C46-3 (VOUT1) - body ground OL good
A36-19 (VC) or C46-4 (VC) - body ground OL good

I’m not sure if this high pressure fuel rail reading is a red herring or not because from my understanding the FA20 uses port injection for starting?

The most recent test I did was checking ignition, so I took out all the coils, disconnected the port injectors per service manual, stuck some old spark plugs in the ends of the coils and grounded them. The ignition coils in the video going from left of the frame to right is 1-3-4-2. 3 and 4 are closer to the engine and 1 and 2 are further away because that’s how far the wiring harness reaches:

https://youtu.be/biHpl4DOpxo?si=Zu7kY_WG6j-0h9td

Now correct me if I’m wrong, FA20 firing order is 1-3-2-4, but in the video they are firing 4-2-3-1?

1-3-2-4 is the correct firing order.

Swapped the engine control modules with a 2017 Toyota 86 unit and identical behavior. Not the ECM.

I took out the ignition coils again to confirm and they are definitely not firing in the correct order.

A friend linked me to a TSB that has a lot of similarities. Trouble starting, rough idle. https://static.nhtsa.gov/odi/tsbs/20...67832-0699.pdf

Additionally, I did replace my timing cover which holds the camshaft position sensors…maybe?

It sounds like the crank shaft sensor plate is out of correct orientation.

Fuel pressure codes may be nothing. I had a lot of weird codes pop with my 15’ that went away that where all sensor circuit out of range or high voltage that I could clear after I started the car but not before.

I've triple-checked at this point. Correct direction, fingers pointing towards the crank position sensor. Flywheel installed flat, so it's keyed correctly to the dowel pin on the crankshaft.

I'm pretty sure you're right. The code hasn't come back for me after a whole bunch of cranking the engine.

I wonder if plug harness is flipped left to right. Haven’t checked myself to see if it’s possible

I timed it 180 degrees off! I have it on video! The first time I did the timing chain install I did it correctly, then took it apart again to do valve lash, and the second time I did it wrong and turned the crank clockwise instead counterclockwise!

There is an nhtsa bulletin in the timing that is easier to follow.

https://static.nhtsa.gov/odi/tsbs/20...87902-5448.pdf

Issue confirmed and changes made!

Pink links should line up with the lines on the cam sprockets.
Blue links should line up with the “link” imprint on the crankshaft sprocket.
The triangles/areows on both pairs of cams on both heads should point at each other at the same time.

If one head is timed 360 crank degrees off, one pair of cams will have their arrows pointing towards each other and the other pair will be pointing in opposite directions. The valves will be fine, but ignition and injection will not happen at the right time and the engine will not run.

Correct timing: