Found a solution to the P0193 CEL

[norcalpb]

Well I got another awesome 3 years out of her before this next P0193! This time it came back with a vengeance. Nothing I did with my OFT helped the disabled throttle. It happened as I was warming up the car for my next track session. Car now has 193,000 miles and I think I’m gonna finally start replacing parts. New HPFP, sensor, and radiator on order. I will post back when it’s all put together again.

[mkodama]

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?

[tomm.brz]

i have 1065 flashes on my ecu.
No one has ever seen a corrupted ecu in this car, Subaru and toyota swap them because they aren't allowed to reflash the ecm, only to update it if it's out of date
but surely you can try with another ECU if you have someone near you, but must be same generation and same transmission

[mkodama]

Originally Posted by tomm.brz

i have 1065 flashes on my ecu.
No one has ever seen a corrupted ecu in this car, Subaru and toyota swap them because they aren't allowed to reflash the ecm, only to update it if it's out of date
but surely you can try with another ECU if you have someone near you, but must be same generation and same transmission

Thanks, good to know.

I was monitoring HP fuel rail pressure with my OEM tune and the E85 tune. OEM tune is pinned at 204.00MPa while the E85 tune is at 4.00MPa and then slowly rises to 10MPa. The tune and OFT are seeming much more suspect.

[norcalpb]

Originally Posted by mkodama

Thanks, good to know.

I was monitoring HP fuel rail pressure with my OEM tune and the E85 tune. OEM tune is pinned at 204.00MPa while the E85 tune is at 4.00MPa and then slowly rises to 10MPa. The tune and OFT are seeming much more suspect.

Here is my diag from the local shop I had my car towed to. I since had it towed back north so I get to be the one to do it.

"Verified customer concern. Found code p1604 start ability malfunction and p0193 fuel pressure sensor circuit high input and p0087 fuel pressure too low began by using scan tool to monitor fuel pressure noticed high side pressure at 56 psi indicating a fault with high pressure side disconnected high pressure fuel pump spill valve and verified circuits are ok and found no issues applied power and ground to spill valve and noticed no change in pressure indicating faulty high pressure fuel pump also noticed erratic pressure readings from sensor one second reading 3000 psi and the other second about 1000 psi then 50 verified sensor connection was ok and circuits ok indicating faulty fuel pressure sensor recommend replacing high pressure fuel pump and pressure sensor"

I've also had minor suspicions about the OFT being the cause. It doesn't help that my p0193 journey began directly after I loaded my first tune 10 years ago. But even though flashing between tunes and using a scan tool to clear the permanent code have miraculously fixed the car, this time nothing is working. I can clear the code, but after 10 minutes of semi-rough idling the car begins to choke, and you can really hear this by how loud the direct injectors are. Then it withers all the way to a stall.

When you rebuilt your engine, did you replace the HPFP with the 2018 revision?

[mkodama]

Originally Posted by norcalpb

When you rebuilt your engine, did you replace the HPFP with the 2018 revision?

I have a 2017 engine so I already have a slightly different HPFP and reduced lift cam lobes if I remember correctly.

What updates happened for 2018?

[norcalpb]

Originally Posted by mkodama

I have a 2017 engine so I already have a slightly different HPFP and reduced lift cam lobes if I remember correctly.

What updates happened for 2018?

To be honest I'm not too sure on the differences, I know the newest one was released as a "fix" for the crickets noise.

The newest first gen fuel pump is flat on the top, whereas the older ones are rounded on the top.

Here is the TSB:
https://static.nhtsa.gov/odi/tsbs/20...53209-9999.pdf

[mkodama]

Originally Posted by norcalpb

To be honest I'm not too sure on the differences, I know the newest one was released as a "fix" for the crickets noise.

The newest first gen fuel pump is flat on the top, whereas the older ones are rounded on the top.

Here is the TSB:
https://static.nhtsa.gov/odi/tsbs/20...53209-9999.pdf

Yep, those are all the parts that came on my 2017 car. No cricket noises yet!

[norcalpb]

Originally Posted by mkodama

Yep, those are all the parts that came on my 2017 car. No cricket noises yet!

I need a few more test drives to confirm, but switching to your car’s year fuel pump and a replacement pressure sensor has the car running well again. I’m not sure which of these made the biggest difference but I’d bet it was the sensor.

[mkodama]

Originally Posted by norcalpb

I need a few more test drives to confirm, but switching to your car’s year fuel pump and a replacement pressure sensor has the car running well again. I’m not sure which of these made the biggest difference but I’d bet it was the sensor.

Sensor makes the most sense.

So far I haven’t had the issue come back on my car, but I have the replacement sensor ready to go.

And enjoy the new fuel pump. Mine is still like new after 63 trackdays, half on E85, so I guess it’ll hold up for the life of the vehicle.

[norcalpb]

Originally Posted by mkodama

Sensor makes the most sense.

So far I haven’t had the issue come back on my car, but I have the replacement sensor ready to go.

And enjoy the new fuel pump. Mine is still like new after 63 trackdays, half on E85, so I guess it’ll hold up for the life of the vehicle.

I hope it lasts a while too. I wish I took the time to inspect the roller on the bottom of the HPFP's cam follower but taking that piece out requires some specialized rtv when putting it back so I wasn't going to mess with it.

I was able to go on a 20-minute test drive and the car is driving great again. Situations where I felt I had to slip the clutch more than usual to keep the engine happy is now causing me to chirp my tires. Time to relearn the car I guess haha.

[mkodama]

Originally Posted by norcalpb

I hope it lasts a while too. I wish I took the time to inspect the roller on the bottom of the HPFP's cam follower but taking that piece out requires some specialized rtv when putting it back so I wasn't going to mess with it.

I was able to go on a 20-minute test drive and the car is driving great again. Situations where I felt I had to slip the clutch more than usual to keep the engine happy is now causing me to chirp my tires. Time to relearn the car I guess haha.

Mine had zero wear on the roller; just a little bit of wear on the bucket above the roller from rocking, but nothing of concern.

If you do want to ever take the pump out you can use Nissan 999MP-1217H sealant and a high leverage ratio caulking gun. It’s cheaper than Subaru or Toyota for the same Three Bond 1217H.

[norcalpb]

Just as an update; the car is driving amazingly now. See everyone in 2028 for my next breakdown

[FrickingReallySlow]

Can pre-facelift FRS use a 2017-2020 HPFP? is it hard to replace to get rid of the chirp sounds

Originally Posted by norcalpb

I hope it lasts a while too. I wish I took the time to inspect the roller on the bottom of the HPFP's cam follower but taking that piece out requires some specialized rtv when putting it back so I wasn't going to mess with it.

I was able to go on a 20-minute test drive and the car is driving great again. Situations where I felt I had to slip the clutch more than usual to keep the engine happy is now causing me to chirp my tires. Time to relearn the car I guess haha.