LLY: 03 lb7 to Lly swap

[lbydmax@diesel]

Another Lly swap thread.

Finishedmy Lly swap for about a month now. Everything was plug and play. Havin a few issues though fuel gauge is backwards reads full when empty. Can't get alternator to work correctly. Has 2 wires brown/grey when grey wire is connected truck won't run rite. Idles rough and has killed 2 alternators. Cut the grey wire which tells the cluster not charging and it runs fine but will only charge battery while in drive and have 14 volts on gauge. Another issue when I try to hook up my Ppe tuner and tune it truck will fall on its face doesn't build boost correctly shifts to early at any power level. Put it to stock runs like it should great on power... Anyone else who has done this swap and any of these issues?? Already swapped ecms. Same problem


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[dirty_max]

bcm tcm and cluster? just spit balling here, not very familiar with the electronic aspect.

 

[lbydmax@diesel]

Cluster is the same tcm also. Bcm gonna look into. Only mods to the Lly are full egr delete Ppe ported rail fittings Ppe race valve Lbz mouth piece turbo down pipe.


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[07keo02]

You either have to swap the values for the fuel reading around with efi live or use an lly sending unit for the gauge issue. Not too sure on the other issues. I assume you did the full swap, including all electronics? Is the alternator from the lly motor or your lb7, could be a differen amp rating which they plug in different locations but I don't think that would give you that issue. Only thing I can think of on the tuner is that it is up to date for the new year motor and is fully compatible.

 

[lbydmax@diesel]

I've read on other forums about the fuel gauge and fixin that with efi live. Which I will have done after I figure out these other problems. Alternators I've tried from Lly and lb7 same alternator same issue. Rite now it's running with a 04 escalade alternator with the grey wire to it cut.


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[RPM Motorsports]

Reverse the fuel tables and tweek the MAf sensor for the LBZ mouthpiece with EFI. Alt.., never had that issue, something must not be right in your harness.

 

[juddski88]

ALT issue sounds like something in the fuse box or a ground in the wrong place

 

[lbydmax@diesel]

Truck just came in to my work gonna tear out the harness and swap it. First gonna swap out bcm and fuse box see what she does.


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[RPM Motorsports]

If it was a running truck before the swap don't waste your time with the BCM or fuse box. Unless you used the fuse box as part of your swap. Check all connections and grounds (back of DS head, front of block both sides, frame behind DS bumper) if the motor was from a wrecked truck go through the harness. The wires get pinched 1/2 the time.

 

[lbydmax@diesel]

Yes truck was running before. And Lly was from wrecked truck. Gonna go through all the harness and grounds tonite.


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[lbydmax@diesel]

Haven't been on in a while. But figured out my issues. Bad ECM and bad harness. Now just need to get efi live to get maf tables done for Lbz intake and egr turned off.

 

[gmac32]

I just did the swap last weekend in an 04. I didn't swap anything but the harness and ECM. I tuned it with efi and reversed fuel sensor tables and it ran great

 

[07keo02]

I just did the swap last weekend in an 04. I didn't swap anything but the harness and ECM. I tuned it with efi and reversed fuel sensor tables and it ran great

You swapped the FICM right?

 

[Dee Perry]

No you dont relace the FICM. You use the lly FICM.