LLY: Ficm interchanges?

[02greysixer]

Trying to figure out my truck. I thought maybe it was the cp3 but I'm still not sure enough to just throw one at it since it builds good pressure. It has a substantial miss, cuts in and out, shuts off, extremely hard to start. All the while though the rail desired and actual are spot on perfect. So are the balance rates. Even when I have to crank for 15-20 seconds the actual rp will climb to 15k psi before it starts. Then it will start, knock like hell, shake, then smooth out and be normal. No smoke. I'm going to do bottle tests today to see what that gets me.
But if they are normal within spec I think I'm going to swap ficm's with a buddy to see what happens. Will they interchange without hurting anything? His is also 05lly
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[jc1843]

Have you addressed this common LLY problem--

At the passenger side of the alternator-- the FICM wire harness is tied down to the FICM bracket with a zip tie. The sharp corner of the FICM bracket cuts into the wire loom and the wires. Cut the zip tie and inspect the wires inside the plastic loom. Repair the wires as necessary-- Best to isolate the harness with a short piece of heater hose. Common problem with LLY engines.

 

[02greysixer]

Yes I have. Twice. And ice picked all injectors. I don't think this is a common lly issue. I'm also starting to wonder if it is indeed a fuel issue. It just runs to strong when it's on to be a bad pump. I feel like The miss and cutting out is also to violent to be fuel related. It's bad enough it chirps the tires when it goes in and out. I've been in trucks starved for fuel, this feels different.

It's it at all possible or heard of for cam or crank sensors to fail and cause an intermittent cutting out issue? I got a code p0374 code this morning when it was acting up bad. I know that isn't a cam or crank sensor code but it got me thinking about them for some reason. It has since cleared up and only breaks up when over 2800 rpm now

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[02greysixer]

Reluctor rings for cam and crank are both tight and where they're supposed to be. Both sensor ends were in tact and not broken. And I swapped my ficm into a buddy's 05 and his truck ran perfect. So that tells me it's working fine. Going to try a crank sensor when it gets here Tuesday

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[jc1843]

Check the cam sensor-- and wiring. Someone had that code, and when he removed it, it came in two pieces.

 

[02greysixer]

I'm going to check wiring in the morning. Weather ran me inside for the last time today. The cam sensor itself did look good though and was in one piece.

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[02greysixer]

I believe the truck is fixed. Crank sensor seems to have done it, only driving it will tell for sure. But as of now the tach is working right, it cranks better, revs smoother, and the tranny even shifts better

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[DuramxMan]

Is there any way to check the resistance of the crank sensor?

 

[BlkMax]

If you didn't get it yet, check the ground wire to the block down low on the passenger side. All sorts of bad things happen if that is loose.