some LS questions

[colonel mustard]

what is up all yall.

so, I'm ready to do this. I decided on 6.0 ls. and I have some questions.

I am keeping my sm465 trans. when I get the trans mounted up and engine in...is the LS factory wiring harness no longer needed? it should be replaced with an aftermarket harness correct?

also what is the most reliable engine management system? are yall just using the ecu that came out of the donor truck? if so does that ecu need to be flashed?

 

[4WDKC]

what is up all yall.

so, I'm ready to do this. I decided on 6.0 ls. and I have some questions.

I am keeping my sm465 trans. when I get the trans mounted up and engine in...is the LS factory wiring harness no longer needed? it should be replaced with an aftermarket harness correct?

also what is the most reliable engine management system? are yall just using the ecu that came out of the donor truck? if so does that ecu need to be flashed?

It doesnt need to be replaced but can be. Stock ecm is the cheapest as you can usually get them with the engine from the donor, or buy in a yard for as low as $35 plus harness.

 

[colonel mustard]

so keep the ECU but get a new harness

 

[Crispy]

The ls harness is stand alone in a way. You can use the oem harness as is from the donor, you can use the stock harness and modify it by removing unnecessary circuits, you can send the oem harness to a 3rd party for the previously mentioned modifications, or you can buy a 3rd party stand alone harness. The last two options start at around $350 and go up.

Look up videos on YouTube for diy ls harness and determine if your time or money is more valuable.

 

[smurfasaur]

As others have said, stock ECM can be used as long as you’re sticking with the stock fuel injection. Go backwards to a carburetor or aftermarket FI and you’ll need an aftermarket controller.

You can use the stock harness and rework it to take out the unnecessary stuff as Crispy said, which is what I did in my swap. However, knowing what I know now and how much time I spent on getting it right (months), I would purchase an aftermarket harness if you have money in the budget for it. Howell EFI makes very good harnesses and are pretty competitively priced. I think they’re around $650-850.


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[colonel mustard]

this is great info guys...

can you give me some examples of unneccesary circuits? I plan on keeping the 6.0 ls stock other than a cam.

 

[Crispy]

Rear O2 sensors, EVAP / EGR / emissions stuff, air conditioning, Low oil pressure, low coolant, fuel composition. There are more. If all you're doing is a cam then stock PCM is good to go. Just make sure you give the cam specs to the tuner.

Watch these videos and decide if you're gonna budget for a harness or DIY.

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[Camar068]

@Crispy good example. It references LT1swap as well. Biggest thing is doing as much research as you can prior to the install so you have fewer "oh ****" moments and waste money cuz you bought something when you'd rather you'd bought the "other" brand (as an example).

 

[Crispy]

LS Swaps arent necessarily bolt in, but they are so common and have been done on so many vehicles that you can spend hours researching and learn where the tricky spots are. This will make the swap easier.

BTW, I believe those videos are by the owner/operator of LT1swap.com

 

[Camar068]

yeh there was another set of vid's that looks similar, mixed 'em up lol.

 

[Duckylsx]

I've done a few square body ls swaps.
Unless you have tons of extra time, buy a painless harness.
With purchase they will unlock and flash your stock ecm.
Great customer service and there is no way to make a harness simpler.