No I haven't messed with the injectors and they came with the engine. One of the very few parts I haven's touched. No idea what the scaling is and haven't done it.
CK5
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No I haven't messed with the injectors and they came with the engine. One of the very few parts I haven's touched. No idea what the scaling is and haven't done it.
You can do a search on HP Tuners site for how to do the injector scaling and I would pull the fuel rail and check the injectors for being plugged.
Amazon sells a nice kit you can pulse them on the bench.
Something else worth looking at are the gear ratios. If those numbers are wrong, you could hit one of the drivetrain torque limits. Without knowing which gear the trans is in and whether or not 4x4 is engaged, it must assume worst-case. It's probably going to correctly assume 2.43 first gear.
I know I keep bringing up trans settings, but without knowing there is no output speed sensor on the trans, the math would be converter stall/trans slip = engine RPM. Of course, it wouldn't know it's in park, either.
I know I keep bringing up trans settings, but without knowing there is no output speed sensor on the trans, the math would be converter stall/trans slip = engine RPM. Of course, it wouldn't know it's in park, either.
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I know for a fact an 8.1 will run with a dead cam sensor as I’ve driven a few Workhorse RVs with cam sensors offline either because the harness got ripped out of the timing cover due to a shredded serpentine belt or just a failed sensor. They will run, but not as good as they should. Most often they’ll have a prolonged crank to get them started while it tries to figure out TDC, other times they’ll start very close to normally. Engines engine only stop in one of 4 same locations anyway. If you’re really lucky, you’ll hit it just right and they’ll aways start on the first try with no fuss then haunt you again with higher RPMs. I’m not saying this is his issue, but verifying 3 wire positions in a connector costs nothing but 30 seconds to verify.
Personally, I’m still leaning towards a fuel supply issue, leaky injector or wiring issue. Not a tuning problem. We’ll hopefully find out soon enough once I can send him the tune from my K10 and Suburban. I don’t see a different tune changing the outcome but it sure would be nice if it did.
At one point it had a P0172 and 0175 code. GM strategy based diagnostics first wants the O2s and MAF verified then goes directly to fuel system diagnosis.
My money is with Larry on this as well, fuel issue. And I go right to the pressure and volume you've already seen.
While waiting for the new pump and regulator, if the injectors are unknown as factory you can double check the injector data matches what is in the tune. If they are incorrect then there are other issues. Even if they are incorrect fuel pressure and volume is still step 1.
While waiting for the new pump and regulator, if the injectors are unknown as factory you can double check the injector data matches what is in the tune. If they are incorrect then there are other issues. Even if they are incorrect fuel pressure and volume is still step 1.
The cold starting issue is still happening btw. I have to give it a little throttle input for 15 seconds otherwise it starts and dies over and over until I give it throttle. Warm it fires up no problem.
Leaky injector, check valve in the pump or fpr will cause the extended crank. Pretty easy to watch with a gauge on the rail. Put the gauge on it and run it for enough time to stabilize fuel pressure. Shut it off and watch the gauge.
It should hold pressure within 10 psi of what it was running at for an hour. It will naturally bleed off a little but not a ton. If you already only had 51 running and it drops more than 10 psi sitting the pump has to run more than the 3 seconds it takes to prime the system when you turn the key on. The engine will not start at 40 psi or less. Cycling the key a second time usually moves enough volume to fill the rail and get the pressure up enough to have the injectors work right.
The extended crank could be the crank sensor being wired wrong. We had to repin the cam sensor connector on my harness as it was set up for the early style and my replacement was a later style. It’s an easy fix to do and even easier to validate it’s right or wrong by looking at it.
It's definitely over 50 psi when I start it. I'll double check the residual pressure tonight however I remember it was holding 50 for quite a while.
Same for the cam sensor wiring, I'll check that tonight.
Cam sensor wiring looks correct.
Fuel trims reset and I have fuel pressure finally 
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Looks good from here
Check your email. Got a EFI Live copy of my tune sent to you and another copy coming hopefully, tomorrow in HP Tuners format. Not sure if it really matters what tuning software was used to copy the tune but one or the other should work for you
The resync has always done it for me.
Even then with the torque management it should fall on its face like that.
Even then with the torque management it should fall on its face like that.
I think I figured out the issue. I was modifying the tune from the 1st PCM and trying to upload it to the 2nd PCM.
That’s weird that resetting the fuel trims got you more fuel pressure, not sure how that works.
The added psi came from an aggressive dude with tool giving that little screw hell
lol that makes sense
