Long crank on warm start, 2012 Impreza

[JayS]

Posted this original over in the Impreza thread but really wanted to get it over in tech where it might get more views/help. Couldn't post here originally because I was new and didn't have 3 posts yet.

Got my daughter a 2012 Impreza Sport Limited wagon, 93k miles. Runs great, no codes, but sometimes gets a long crank to start. Almost always starts perfectly when it's cold. Much more likely to get a long crank if you drive it until it's warmed up, park, and then restart it within an hour or two. Turn key off, try again, most of the times it starts right up. Every now and then it takes a 3rd try. When it starts it runs perfect. Throttle response is great, car NEVER stumbles or misses.

What I've done so far.
Checked battery voltage, fine at 12.6 volts. Load tested at Autozone, passed at 95%. Battery is a Duralast from 2022.
Scanned for codes, nothing, not even pending.
Replaced the crank sensor, no change.
Replaced the plugs with NGK 92274 Ruthenium HX, no change. Old plugs looked good.
Removed and cleaned EGR valve. Had a decent amount of carbon buildup. No change.
Removed and cleaned the throttle body. Wasn't that dirty honestly. Did the idle relearn after this job as the idle was bit off, likely because I had the battery disconnected so long while changing the plugs. Idle was perfect after the relearn, but no change on warm start.

I did see there was a service bulletin about this issue for 2014+ cars but couldn't find anything about 2012 so going to stop by the dealer and see if there is something I just didn't find there. Kinda out of ideas at this point. Don't think it could be fuel pump since it runs perfect once it starts. Tried reading some real time data with my bluetooth OBD2 adapter and ODB Fusion app but didn't see any options to read fuel pressure like I can on my wife's Buick Enclave. Going to hook up a physical fuel pressure tester to see what's happening during a long crank as soon as I have time.

Air filter looked really clean. I had it out when I changed the plugs because that required pulling the air box for access. I ran a bottle of techron fuel cleaner through it a few weeks back.

Last night I took it over to a friend's shop that had some Subaru software to read all the sensors, but he thinks his software didn't have the right configs for this specific Impreza. Specifically he wanted to see the readings coming off the fuel pump. He was able to dump the ECU file so he was going to look into why he couldn't see all the systems he normally could and rescan it when he figures that out. He and I are both confident it's a fuel issue with something causing the ECU not to deliver enough fuel on warm start.

Any help greatly appreciated. First Subaru so I don't know this platform that well. Pretty advanced shade tree mechanic and willing to pick up some Subaru specific tools/software since I expect my daughter will have this car for a while. I already have the Rosstech cable and VCDS for my Audi S5 so I'm familiar with digging deep into manufacture specific coding, just haven't had to do it in the Subaru world before so no idea what is needed.

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[AceKingNYC]

It's kind of a known issues with subarus, i think there may even have been a TSB for the '14 Impreza. Some info can indicate it being a faulty fuel pump, but if the car runs perfectly fine after startup then i do not suspect that is the issues.

I am also experiencing this issue with my wife's Forester. It usually starts right up but sometimes it cranks for like 3-4 seconds before finally firing up and then it's fine. It could potentially be the fuel check valve (it's in the fuel pump) that's releasing fuel back out of the lines, rather than holding them there for startup.

The reason is happens after warmed up is most likely bc the heat could be affecting some of the gas/vapors. One thing I read was to turn the car on to ACC for about 3 seconds, shut it off and repeat this about a half dozen times. I just did this a few days ago and asked my wife to let me know if it takes long to start again or not. Overall, i don't think it's anything to be super worried about, especially since you've already replaced some parts and it runs fine

[EloMungo]

I was going to post about this myself, I have a 2013 XV. Been running fine, but sometimes cranks a while before it starts. Checked battery acid strength in the summer, all was fine.
Car has 175K Km's on it.

The only other issue I've noticed is that though very rare & no code comes up on the scanner, the recirculation button flashes, any ideas what's that about?

[EloMungo]

I was going to post about this myself, I have a 2013 XV. Been running fine, but sometimes cranks a while before it starts. Checked battery acid strength in the summer, all was fine.
Car has 175K Km's on it.

The only other issue I've noticed is that though very rare & no code comes up on the scanner, the recirculation button flashes, any ideas what's that about?

[JayS]

It was the ECU software update. Took it to the dealer tonight, showed it never got the update that came out in 2015. Flashed the ECU and it’s started perfectly since.

[mjdejan23]

Originally Posted by JayS

It was the ECU software update. Took it to the dealer tonight, showed it never got the update that came out in 2015. Flashed the ECU and it’s started perfectly since.

Do you remember what was the Technical Service Bulletin number that the dealer updated? Or the .PAK file number?

[JayS]

Originally Posted by mjdejan23

Do you remember what was the Technical Service Bulletin number that the dealer updated? Or the .PAK file number?

They never gave me any of that. Just hooked the car up and once their computer ran the VIN it saw an update was needed. Since it was done on the side by a tech for cash I don't have an invoice I can check or anything.