I have seen the impossible!

blk smoke lb7

blk smoke lb7

<-----Lots of green $
Nov 8, 2010
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RPM Motorsports said:
03-04 you just use the LLY harness NSBU and ECM, do an emergency relearn and away you go, it's that simple.
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use the lly ecm? and harness i thought the original guy used all lb7 stuff except using the lly heads and splicing in the injector wires?i want to use the lb7 bridge so i dont have to change ic pipping and intake and all that stuff
 
RPM Motorsports

RPM Motorsports

smokinum
May 13, 2008
3,271
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Central Valley Ca.
Re read, there are two different swaps that are being talked about between the 01-02 and the 03-04.
You having an 04, could grab a complete early Lly with harness, ECM, NSBU, Lly cold side boost tube, Lly intake. Drop it in the truck, plug the harness in, do an emergency relearn and away you go.

01-02 a lot of work mixing and matching, and a few ways to do it.
03-04 plug n play
 
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RPM Motorsports

RPM Motorsports

smokinum
May 13, 2008
3,271
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38
Central Valley Ca.
THEFERMANATOR said:
The origanal poster here said he tried this and the LB7 ECM would not talk to the LLY FICM, this is why he said he went back to an LB7 FICM and made the hybrid harness.
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Just for the hell of it I tried an LLY FICM and it didn't work, the LB7 FICM fires right up. I'm glad because I have a bunch of LB7's laying around from other swaps ;)
 
D

dirtybutclean

New member
May 30, 2012
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Okay i have the opposite of everyone. lol. I bought a 04.5 lly truck that somebody put a 01 lb7 in. when i got it ran rough, 4 blown injectors and a bad wiring harness. just put a new set of injectors and it still ran rough. fuel pressure is through the roof at idle its about 20000+... it was running on an lly ficm and lly ecm. swapped to lb7 ficm now it wont start. took it to a shop to flash it, still wont start.. I have efi live but dont know enough... anybody have any insight? thanks!
 
Trippin

Trippin

SoCal Diesel
Aug 10, 2006
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The ECM and the Ficm need to match each other. The LB7 and LLY ecms and ficms communicate using different protocols.
 
duratothemax

duratothemax

<--- slippery roads
Aug 28, 2006
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Trippin said:
The ECM and the Ficm need to match each other. The LB7 and LLY ecms and ficms communicate using different protocols.
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They are both use the same J1939 250k CAN databus standard (otherwise you wouldnt be able to swap LB7 and LLY TCM's), so is it just the messages themselves that are slightly different?

Its odd that GM would make the LB7 and LLY FICM incompatible. The databus never changed from 01-05 and was the same until 06 when they went to 500k GMLAN/CAN2.0.

Or maybe GM actually put some identifier message in there specifically to prevent someone from using an LB7 FICM in an LLY.......
 
D

dirtybutclean

New member
May 30, 2012
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the 01 lb7 ran with the lly ficm and ecm but the rail pressure is stupid high. Which i thought the ficm would cause by not letting enough fuel through and causing high pressure. Can i run the lb7 computer on a 04.5 truck somehow? all i want to do is fix and sell it right away.
 
duratothemax

duratothemax

<--- slippery roads
Aug 28, 2006
7,139
10
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Wyoming
Just unplug the LB7 ECM harness from the fuse box and plug in the LLY ECM harness. Thats all you have to do. Its plug and play.

The LB7 TCM will work fine.

You will need EFILive only because the fuel sending unit on the LB7 and LLY is reversed. If you dont reflash the LLY ECM with a flipped fuel sending unit table, the fuel gauge will read backwards.

But you dont need EFILive just to get it running.
 
THEFERMANATOR

THEFERMANATOR

LEGALLY INSANE
Feb 16, 2009
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duratothemax said:
You will need EFILive only because the fuel sending unit on the LB7 and LLY is reversed. If you dont reflash the LLY ECM with a flipped fuel sending unit table, the fuel gauge will read backwards.
Click to expand...

I thought the switch over was 06 with the LBZ, but I went and looked at an LLY VS LB7 and seen it in it. That's wierd that GM would have made a change mid year like that, and even stranger that they kept the gassers with the early style for longer.
 
T

troutfisher

New member
Jul 29, 2012
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Very interesting the injectors are out on my 02 lb7 and I can get a 05 lly for $1000 so it looks like I will be doing this swap also. I have a couple questions do I need lb7 or lly head gaskets and should I put in head studs or just new bolts not going to be trying to make big power also is anyone selling the injector harnes for 01-02 LB7 to LLY/LBZ swaps and does anyone have a tune for this or what do I need to do to mine I have read the thread several times but just dont understand what to do to the tune I am running a dsp 5 from Idaho Rob.
Thanks Ed
 
C

Calgary

New member
Jul 16, 2012
4
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Calgary AB
im in the process of the lly engine swap from 01 lb7 to a 05 lly rite now. i found the injector wire colors are not the same. just swaping spot for spot on the c1 and c2 clips. see how it works out . Any advice from people that have done the swap would be helpfull....also what other road blocks have you guys run into.
Will
 
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