LMM CP3 on LLY engine?

[WVRigrat05]

I was gonna buy an lmm cp3 for my lly before i drowned it and I looked up what else I was gonna have to change and I found that thread, and from what got out of that thread I was gonna have to swap the wheels for it to work if I bought a used one with a wheel on it.

 

[hondarider552]

Nosir, that's only when you start swapping crankshafts in builds.

 

[WVRigrat05]

Oh, guess I should get my head out of my ass.

 

[Sud]

Mitch = copy cat. lol

Nah i think i may be just as well off leaving mine alone, since it doesn't seem to be weak at this point. However, I am going to try to check things out a little more closely with the CTS, just to make sure i'm not losing any rail pressure during a hard pull and just to see what all is happening.

if the pump is holding good pressure throughout, i may just put the FPR in it and leave it alone.

 

[Sud]

Drove the truck and checked rail pressure - got in throttle enough to get rail pressure up to 23k psi. held it there for at least 20 seconds - never dropped below 22k psi (saw 22 for a brief second then back up to 23 psi.) Watched it from rpm range of ~2000 - 2900.

As for the regulator - one morning it was about 50* out. started the truck, and i should have took a picture, but desired frp was around 5k-5.5k; actual frp was fluctuating from 13k-14k.

wayyy to high at idle.

as it warms up it gets better, but even warm the actual rail pressure will sometimes raise to as high as 8k-9k, while desired will be around 4.9k-5k.

When you hit the throttle and actually drive the truck, actual and desired stay within .2k psi of one another.

Is this a regulator issue?

 

[RPM Motorsports]

Lift pump psi set too high will do exactly that ^^

 

[Porno Joe]

I went the same issue with my lbz with dual pumps. Turned out it was in the tune. The tune only allows the regulators so much range, and mine was actually trying to close more than it could.

Mine would command like 4500 but actually would be 7-8k.

Quick check is when the rail pressure goes up unplug the lift pump and wait for like a minute. If if comes down it's the pump