2003/2004 LB7 to 2004.5/2005 LLY conversion

[Tlisenby]

I have a 2004 LB7 crew cab short bed with a manual transfer case. Long story short I hit something in the road, found out 5 miles down the road that all the oil in my truck was gone. Insurance cashed me out and I’ve been wanting to go with a lly swap. I need solid info I’m so tired of hearing what people think it needs. I’d love actual information from people who wrench and have done it personally.

From my understanding the automatic 2004.5 to 2005 5 speed lly and the 2003 to 2004 lb7 are very similar in aspects of wiring.

I’ve never done the swap personally. If I order an engine from my local truck dismantler what all should I ask for? Don’t just say everything because they are gonna charge me for everything.

More than likely it’s gonna come with engine harness, turbo, ficm and maybe the accessories like the alternator, compressor, stuff like that.

Can anyone give me REAL DEAL information?

 

[Cougar281]

I'd just jump straight to a LBZ, but that's me.

For a LB7 - > LLY swap, you'd need the engine, engine/transmission harness, ecm, NSBU, GPCM, not sure if the accelerator is the same for LLY and LB7, alternator and ac compressor should be the same, some of the intercooler piping is different I believe.

LBZ would need everything the LLY would need plus TCM and either a complete transmission or swap the valve body and wiring, instrument cluster, shift lever, accelerator pedal and mounting bracket, and add some wiring for tap shift and the DLC.

I may be missing a thing or two... Its been a while since I swapped a LBZ into my 04 LLY.

Sent from my 2PZC5 using Tapatalk

 

[TheBac]

No need for the huge font. Its completely understood that you're upset, but treat the forum with some respect and you'll get it back.

Moved to Repower/Transplant. Lots of threads in here about LLY or LBZ swaps. Read away.

Anyway, Cougar has it down what's needed for the swap either way you decide to go. Quite a few others have done these swaps too and can help if needed.

 

[White Duramax]

I swapped an 03 to a LLY last year, Cougar is right on the parts. One other issue is the fuel gauge will read backwards, will take an efi live tune or swap the sending unit in the tank to a newer one.

 

[Tlisenby]

So as long as I get the engine pretty much complete, I should also ask for the under hood harness and the ecm? I planned on a lift pump, fuel filter head bypass, y-bridge, passenger side up pipe, efi live, bigger down pipe, it’s already got the cat deleted, intake, full 5” exhaust, and an upgraded hot side charge pipe.

 

[Tlisenby]

Also will there be any problems with the vvt? Does any wiring need to be de pinned and re pinned?

 

[DylOrr]

Also will there be any problems with the vvt? Does any wiring need to be de pinned and re pinned?

That will be taken care of when you swap all the harnesses. To do a swap I’d recommend a donor truck. Trying to piece one together gets crazy expensive, especially because LLY stuff is expensive.

 

[RPM Motorsports]

Also will there be any problems with the vvt? Does any wiring need to be de pinned and re pinned?

03/04 LB7 to LLY no re pinning needed, just install the LLY body side harness with ECM where you remove the LB7 harness. Since you’re most likely keeping the LB7 trans, keep the LB7 TCM. If you install an LLY trans, use the LLY TCM. If you get a complete motor and harness, ECM, intake, LLY NSBU and pass side boost tube you’ll be set.

 

[Nothinbuttroubleduramax]

Can we bring this topic up again? I broke the crank in my 03 lb7 so I swapped it out for an lly. Changed harnesses, ecm, etc. everything listed above in this post. Changed fuel rail fittings and plug with PPE fittings, egr delete and pcv re-rout. Still have the stock intake for now. Installed a new fuel pressure regulator while o had everything apart. Got the motor in the truck and had the ecm reflashed and tuned. Truck is running a small 110 lift pump and I can’t get the fuel rail pressure I need. Key on it shows 2.8k and cranking goes up the 3.4k. Lift pump doesn’t have a filter so I run through the stock filter so I still have the primer. I can prime the fuel until I can’t pump anymore and the motor will fire but I can’t keep it running without pumping the primer. And I have no throttle response. If I unplug the fuel pressure regulator and just let the cp3 go full bore it will idle with a nasty lope and smoke like crazy. Still no throttle response. And no matter what I do I can’t get the rail pressure up. I know this could be many things but if anyone has ever had this specific problem I would appreciate the help.