LS Swap question

[skyphix]

Here's what I did:

2006 Yukon was my donor. Had it sitting in my driveway. Its 4wd, and my C10 obviously isn't, so...

1) Pulled the engine complete (including wiring harness... didnt end up using it but its good to have scrap wire around.)
2) Pulled the PCM and Fuse block (didnt use them, but good to have for future)
3) Pulled the accelerator pedal, TAC module, and harness
4) Reused the radiator (ended up having to order a new one, but got a stock replacement for the Yukon) and fans
5) Reused the positive and negative battery cables
6) Reused the battery (which I have since replaced with a replacement for the Yukon... this winter killed the 8 year old battery that was in the Yukon)

You actually can use more - fuel lines and trans cooler lines can be made to work. I went braided stainless from hotrodfuelhose.com and do not regret it.

I did NOT use the 4L60E out of the Yukon... ended up being cheaper to pick up a good condition used 2WD 4L80E which matches my future goals/needs better than having my 60E converted to 2WD and rebuilt.


The rest is going to the scrap yard. I sold enough off of it in parts, even though its rusty, to pay PSI to send me a harness, PCM, 2 position brake switch, and fan relays. Total from PSI was around 900 and truck runs like a dream. They took care of VATS, etc. They also started with a 6.0/4L80E PCM and adjusted the parameters to match my 5.3. I plugged it in per their instructions, wired it up to the chassis harness (really simple,) ran a wire for my fuel pump, and turned the key. See video below. I'll do more tuning myself this spring.

I'm using a dirt cheap Android tablet (that I got for free, but it was $30 new,) a $15 tablet mount, $5 software called Torque Pro for Android, and a fairly expensive (there are cheaper, but I like the higher resolution/refresh rate) bluetooth OBDII sender ($70) for my gauges and idiot lights. I did have to grab an oil pressure gauge, sender, and adapter, because the Gen 3 PCM I am using doesn't use oil pressure. No big deal for me - actually had everything laying around except the adapter.

Not saying the Holley kits aren't good - they are - I just decided to go GM instead and have zero regrets. I'll likely end up switching to a Holley kit once I add turbo's... but thats a built engine away (2+ years) and for now its nice, on what will be my daily driver, to be able to walk into a parts store and tell them I need X sensor for a 2006 GMC Yukon 5.3 with FlexFuel and they mostly have it on the shelf, even here in middle of no where Maine.

https://www.youtube.com/watch?v=r-xofqe-DgQ

[kev2809]

wow that thing fired right up! im leaning towards finding a whole truck just because its probably cheaper than finding the parts from a junkyard or seller. literally could have had a running 2004 yukon for 800 but decided to fix my avalanche instead

[kev2809]

Originally Posted by skyphix

Here's what I did:

2006 Yukon was my donor. Had it sitting in my driveway. Its 4wd, and my C10 obviously isn't, so...

1) Pulled the engine complete (including wiring harness... didnt end up using it but its good to have scrap wire around.)
2) Pulled the PCM and Fuse block (didnt use them, but good to have for future)
3) Pulled the accelerator pedal, TAC module, and harness
4) Reused the radiator (ended up having to order a new one, but got a stock replacement for the Yukon) and fans
5) Reused the positive and negative battery cables
6) Reused the battery (which I have since replaced with a replacement for the Yukon... this winter killed the 8 year old battery that was in the Yukon)

You actually can use more - fuel lines and trans cooler lines can be made to work. I went braided stainless from hotrodfuelhose.com and do not regret it.

I did NOT use the 4L60E out of the Yukon... ended up being cheaper to pick up a good condition used 2WD 4L80E which matches my future goals/needs better than having my 60E converted to 2WD and rebuilt.


The rest is going to the scrap yard. I sold enough off of it in parts, even though its rusty, to pay PSI to send me a harness, PCM, 2 position brake switch, and fan relays. Total from PSI was around 900 and truck runs like a dream. They took care of VATS, etc. They also started with a 6.0/4L80E PCM and adjusted the parameters to match my 5.3. I plugged it in per their instructions, wired it up to the chassis harness (really simple,) ran a wire for my fuel pump, and turned the key. See video below. I'll do more tuning myself this spring.

I'm using a dirt cheap Android tablet (that I got for free, but it was $30 new,) a $15 tablet mount, $5 software called Torque Pro for Android, and a fairly expensive (there are cheaper, but I like the higher resolution/refresh rate) bluetooth OBDII sender ($70) for my gauges and idiot lights. I did have to grab an oil pressure gauge, sender, and adapter, because the Gen 3 PCM I am using doesn't use oil pressure. No big deal for me - actually had everything laying around except the adapter.

Not saying the Holley kits aren't good - they are - I just decided to go GM instead and have zero regrets. I'll likely end up switching to a Holley kit once I add turbo's... but thats a built engine away (2+ years) and for now its nice, on what will be my daily driver, to be able to walk into a parts store and tell them I need X sensor for a 2006 GMC Yukon 5.3 with FlexFuel and they mostly have it on the shelf, even here in middle of no where Maine.

https://www.youtube.com/watch?v=r-xofqe-DgQ

and if im reading this right...u did not use the stock truck harness....instead had psi build you one?

[mongocanfly]

That's the way I read it...he used psi
The last 2 LS engines I bought came with the harness and both harnesses were ruint by whoever removed them...the 1st harness was evidently cut in 1/2 with a sawzall...then somebody put wire loom over it and I didnt see it until I got it home...resulting in a psi harness
The 2nd engine harness had several plugs cut of it ...so another psi harness..
Unless you pull it yourself , dont expect much...

[kev2809]

Originally Posted by mongocanfly

That's the way I read it...he used psi
The last 2 LS engines I bought came with the harness and both harnesses were ruint by whoever removed them...the 1st harness was evidently cut in 1/2 with a sawzall...then somebody put wire loom over it and I didnt see it until I got it home...resulting in a psi harness
The 2nd engine harness had several plugs cut of it ...so another psi harness..
Unless you pull it yourself , dont expect much...

lol which is why i dont want one pulled from a junkyard...they cut everything up.

did you use the donor truck radiator too or adapted your stock one?

[mongocanfly]

I've always used the stock radiators...they are plenty...but on the IH/LS the radiator was shot...but I had one built back to the exact size...and I've always used electric fans as well...I have dual fans on the C30, and a single fan on the IH..

[skyphix]

Originally Posted by mongocanfly

That's the way I read it...he used psi
The last 2 LS engines I bought came with the harness and both harnesses were ruint by whoever removed them...the 1st harness was evidently cut in 1/2 with a sawzall...then somebody put wire loom over it and I didnt see it until I got it home...resulting in a psi harness
The 2nd engine harness had several plugs cut of it ...so another psi harness..
Unless you pull it yourself , dont expect much...

Originally Posted by kev2809

and if im reading this right...u did not use the stock truck harness....instead had psi build you one?

Correct, I ordered a harness from PSI. Parting out the Yukon paid for it almost entirely in the end. I also ordered a PCM from them. I have two complete engine harnesses and two functional PCMs but I decided to go new on the wiring. 15 or so years in New England isn’t kind to much, including wiring. That said, I now have a bunch of spare connectors and a good amount of good condition wiring to use for other things. And the PCMs will get used as I tune and build other cars. Ultimately it was a lot quicker for me to just order what I needed and be done with it.

I got my Yukon for free from a family member that was sending it to the scrap yard. The engine is a lower mileage GM replacement and she was happy to see it live on. The second wiring harness and PCM came from an engine Im rebuilding. The truck LS engines are so prevalent here that people pretty much give them away. For $150 I got a running engine (bad lifters, hence the rebuild) intake to pan including the complete wiring harness, PCM, and fuse block.

I’ll probably use PSI for the harness for my next swap too. Their support was great and the quality of the harness was good too. The only thing a bit annoying was how short the MAF branch was primarily because I am using the entire intake tract from the Yukon, and they are up front about that. I just picked up a MAF extension but there are other options there as well. The money spent is well worth the time saved at this point in my life. I’d still be building the harness rather than buttoning up my swap if I had built it myself. Time is at a premium right now.

[kev2809]

completely understand....im not in a huge hurry so ill probably go the stock harness route.

i ran through ur build thread and didnt see the tablet gauges u mentioned. do u have any pics of them?

[skyphix]

Originally Posted by kev2809

completely understand....im not in a huge hurry so ill probably go the stock harness route.

i ran through ur build thread and didnt see the tablet gauges u mentioned. do u have any pics of them?

It’s not mounted in the truck currently, but let me charge the tablet up and I’ll take some photos. I have it pretty crowded right now to make sure everything is healthy but I’ll clean it up once I know all is good. I’ll post photos later today.

[LS short box]

Here's my .02.
I've done over a dozen LS swaps on my projects and friends projects. I've had the best luck buying the engine harness and ecm from one supplier. I've used Spear Tech on two swaps and Howell on all the others. I would be the first to admit I'm not an electrical genius so I like buying the ecm and harness from one supplier so if there is an issue only one place to call. With your engine/trans details they can program a base tune that will work until you get it to the "local" chassis dyno to get it perfect. Neither Spear Tech or Howell are cheap. Both use braided wire covering that I think looks so much better than the plastic ribbed covering. I ordered a PSI harness but ended up sending it back because I wasn't happy with how it was configured. They were very good at taking it back and I did speak to the owner about why I was returning it. In the end they seemed like a solid company.
Chassis wiring. Our trucks are old. Stock wiring is old and cracked. I've used Painless to rewire a number of cars and my truck. Autowire seems like a good choice also. Run a good size pos cable from the starter to the alternator. Make sure you go overboard on good grounds. Grounds from battery to frame. Good grounds from frame to engine.
Good luck with your project.

[C.I.Blazer]

This has been a great discussion for me as I am heading into this phase of my project next. I just got my motor and transmission installed over the weekend (huge milestone for me) and am now thinking about wiring. I have been contemplating both the Holley Terminator X system and purchasing a harness and PCM from PSI. The reality is when I finish pricing everything out the difference comes down to about $400-$500 dollars. Once I add in a cheap tablet, ODBII reader, etc. it gets even closer. If I actually want to try and learn to tune myself with HP tuners the cost difference is almost nil. Truly, with everything I am putting into my swap, I am more interested in finding the right solution rather than saving few hundred bucks.

So, my question is this. Outside of the cost, can you give me any advice on selecting between a stock setup versus the Holley. I understand the Holley has advantages if I want to boost my setup in some way (maybe down the road but who knows). But for a daily driver is one better than the other? I do like the idea of being able to use readily available parts. It also appears that the Holley system is a bit easier to learn if I want to get into some tuning on my own.

Gratuitous pic of my install below. Appreciate any input.

[LS short box]

Again I'm no expert but I like the OEM stuff. Nothing against Holley I'm sure they've done their home work to deliver a solid product. I like the OEM stuff because it's so readily available. The OEM's have spent millions of hours to get their systems as bullet proof as possible.
The benefit of Holley as I understand would be the adjustability for engine and trans parameters. And from what I've read on various forums the Holley system has better tuning capability when running bigger cams and such than the OEM. I would confirm with Holley that all "stock" engine and trans sensors are being used.
Might be worth contacting some well known tuners to see what they think. LS1tech would be a good source for tuners that don't supply harnesses so their opinion won't be biased.
Again just .02. Good luck with your project.

[MidLifer]

Board member 68 Four On The Floor used to sell flashed PCMs (VATs and Cats removed) and complete harnesses with the extraneous wires removed for reasonable prices. He may still do so, been a while since I did my swap. That’s what I used and it worked like a charm. Still needed a tune for the PCM but once I got it installed (used LT1swap to help with the fuses/relays/etc) it started right up.

RE fuel hose if you use stainless braided be use to buy PTFE hose or your garage will stink like gas and eventually it will rot and leak. The standard rubber hose doesn’t work with fuel.

No offense on the Holley systems but you can get er done for less cash using OEM stuff if that is an issue.

[LS short box]

I've used the name brand -6 hose with no gas smell or the hoses falling apart. My 98 Wrangler LS swap has over 11 years on it and no smell. BUT and this is a big if I always run no alcohol premium gas. Not a daily driver.
If I was to do it again I would PTFE if it could be routed easily.

[skyphix]

Originally Posted by LS short box

I've used the name brand -6 hose with no gas smell or the hoses falling apart. My 98 Wrangler LS swap has over 11 years on it and no smell. BUT and this is a big if I always run no alcohol premium gas. Not a daily driver.
If I was to do it again I would PTFE if it could be routed easily.

I ran PTFE - I chose to route it down along the outside of the frame, up along the firewall to the fuel rail on a returnless system, but I could have routed it along the inside as well. I took extra precaution to keep it away from the exhaust but that probably wasn't necessary. Mounted the fuel filter/regulator to the frame.

To the OP: I haven't forgotten about taking a photo of the tablet gauge setup for you, but my kids seem to have pilfered my tablet. Still searching for it after the Christmas mayhem.

[prodjay10]

I used the metal fuel/brake lines that bend easy and rubber fuel hose. Fuel injection hose on the supply and regular fuel hose on the return. While it does say not for fuel injection, the regular fuel hose will take up to 50 psi. No leaks no gas smell.

Even though the lines are supposed to be easy to bend they were kind of a pain to run through the chassis.

[mcmlxix]

I picked up a roll of NiCopp (Nickle Copper mix) 1/2" line that is fairly easy to form and is corrosion resistant. At the ends I am swapping over to OEM style nylon flex line with OEM connections for both ends, fuel rail and fuel pump.
Check out last couple pages in by build thread from the link in my signature.

[MidLifer]

Originally Posted by LS short box

I've used the name brand -6 hose with no gas smell or the hoses falling apart. My 98 Wrangler LS swap has over 11 years on it and no smell. BUT and this is a big if I always run no alcohol premium gas. Not a daily driver.
If I was to do it again I would PTFE if it could be routed easily.

That’s great that it works for you. One of the reasons I did my ls swap was to be able to get great performance from pump gas, unlike the finicky carbureted, cammed 350 that preceded it. I made the mistake of originally using rubber braided line and had to switch it out for ptfe. At the time I had kept my cab tank and the cab reeked of gas. The noise of the in-tank fuel pump drove me to change to a Boyd’s rear tank. At the same time I replumbed using PTFE.

Of course hard lines are the safest way to go if you have the skill and patience.
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[Rich84]

I used all the donor lines from the rail to the frame just below my tank. I mounted the filter - regulator there with about 20" of fuel injection hose to the sender. The donor offers all of the clips and bends and fits perfectly.

[skyphix]

Originally Posted by Rich84

I used all the donor lines from the rail to the frame just below my tank. I mounted the filter - regulator there with about 20" of fuel injection hose to the sender. The donor offers all of the clips and bends and fits perfectly.

This was originally what my plan was based on your build, Rich - my Yukon bends all looked great, but it was punky in a bunch of places (rust) so I didn't end up using it.

[verdell]

I've had great results by simply getting the PSI harness AND computer, plugging it up and rolling. Because of my cam selection and stall, I had to have it tuned as well but as far as the install, it couldn't have been simpler. Done it this way with quite a few and the results have all been flawless.

[skyphix]

Originally Posted by verdell

I've had great results by simply getting the PSI harness AND computer, plugging it up and rolling. Because of my cam selection and stall, I had to have it tuned as well but as far as the install, it couldn't have been simpler. Done it this way with quite a few and the results have all been flawless.

Exactly what I did. As soon as I had good fuel pressure, she fired right up.

[LS short box]

In one of the posts above they used regular rubber fuel line rated to 50 psi. Keep in mind the LS engines run at 58 psi.
Yes I can believe an in-tank electric pump with the gas tank behind the seat would drive anyone nuts. I'm running a 69 Camaro rear mount tank from Tanks Inc. 255 Walbro. You can hear at idle but as soon as you put in gear and get moving you can't hear it.

[prodjay10]

Normal fuel hose on return only. Return should have very little pressure. My system is also flex which is supposed to have lower pressure than that stated.

[C.I.Blazer]

Thanks for the input. I am talking with PSI and am probably going to go that route. Wanting a solid, reliable daily driver and no mods to the engine (yet). Should make everything a lot easier.