CA legal LS swap

[JBswth]

There is SO MUCH misinformation out there on doing a CA legal swap! I've now done two. My first was a 3RZ swap in a Toyota. The second was a LQ4 swap into my V2500 Suburban. I thought I'd post some details of the swap while it is still fresh in my mind. This is by no means a replacement for the engine swap guidelines from the Bureau of Automotive Repair, but as you'll see when you look at them, they're clear as mud to the layperson. I hope this article will shed a little light on what is needed to do a CA legal engine swap.

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PART I: MY SWAP STORY

I purchased a 1991 V2500 Suburban. It came with a TBI 350, which back in 1991 had a whopping 185 HP. Transmission was a 4L80E. I was loving the old Squarebody, but the poor old truck couldn't get out of it's own way! The first week of owning it I was already dreaming about engine swaps.

I knew enough details about the CA engine swap requirements to know I needed to pick a donor vehicle that was somewhat similar to my vehicle. Knowing the LQ4 was found in 3/4 ton vehicles, I guessed it was going to be ok in my 3/4 ton Suburban. With what I know now about Emissions Category Certifications, I got lucky. I should have done some deeper digging on the requirements. I'll elaborate later in this article.

I decided the 6.0L LQ4 was what I wanted and when I found a fair price on one at a local wrecking yard, I took the plunge. I knew the owner of the yard, so I was able to take the donor truck home for a month and pull the engine myself. It was really handy having the donor just outside the garage. Anytime I needed a bolt, bracket, clip, etc., I could source one off the donor truck. The donor was a 2002 Chevy 2500HD 2wd. Tranny was a 4L80E, but the yard had already sold the tranny.

Just as I decided to pull the trigger on this engine swap, I got the weekly email that comes from this GM Squarebody forum. In the email was "1991 5.3L 2500 Burb" listed in the engine swap forum by Kelvin. I couldn't believe my eyes! Talk about good timing! You can find the thread here https://www.gmsquarebody.com/threads/1991-5-3l-2500-burb.31558/

I read through the thread and found that he was nearly finishing his swap. I ended up contacting Kelvin and next thing I knew he was texting me his entire parts list, which he's since added to his engine swap thread. Please check it out, so much good info there. Saved me hours of research and tracking down part numbers.

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Using the same motor mount adapter plates as Kelvin, the engine bolted right in, requiring no changes to my transmission crossmember. Technically it required no frame mods at all... however it was really tight at the passenger side manifold, where it bulges out for the EGR pipe. I ground a little steel off the upper edge of the frame to be sure it wouldn't hit the frame when the motor torques over on it's mounts. The other spot the engine is really tight is behind the driver's side head. It did fit without firewall modifications or massaging.

Not knowing how many miles were on my existing 4L80E, I opted to have a local shop with a great reputation (Bob's Almaden Transmission, San Jose) build me a 4L80E. I'm really glad I did. My 91 tranny was one of the first years of the 4L80E and many improvements were made over the years. I also learned one (maybe more than one) of the shift solenoids must be changed out to work with the newer PCM, so I didn't have to deal with that, since I had him build me the correct 4L80E for my 2002 motor.

And now... lets get to the specific CA stuff. CA requires that the motor be 100% functioning as it was from the factory, all the way down to secondary O2 sensors, EGR, EVAP, etc... this was the main reason I wanted the donor vehicle nearby while completing the swap. I wanted to know every little piece was available to me.

The EVAP system requires that the PCM know the pressure in the fuel tank. My 91 tank had no provision for that pressure sender. I ended up filling the tank with shielding gas and then welding a bung to the tank, to get the thickness required to hold the sender. Then I drilled through the bung and slid my sender into place. I read some guys have just put a T in their gas tank vent line and installed the sender there, since it'll be measuring the same pressure. I just kept envisioning getting a stickler of a referee, so I opted to put mine directly in the tank, as it was designed.

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For anybody in California thinking of buying a Square Body and putting an LS in it, your best bet would be to get a 73 or 74, (no smog checks!). That way, you can put a distributor and a carburetor intake on it and no damn EGR valve, no AIR pump, no computers, and no catalytic converter. You can run REAL dual exhausts and Tri-Power in it.

James in California

 

[bs01cam]

Beyond that, you'll need to install the rest of the EVAP system with your donor engine. This includes the purge valve (located on top of the intake manifold), vapor canister (large black plastic box located beside the gas tank) and vapor vent valve (located beside the vapor canister).

For my engine wiring harness, I was using a Painless wiring harness #60217. That harness doesn't include provisions for secondary O2 sensors or fuel tank pressure sender. You must also add Painless emissions control harness #60322, which adds in the wires and connectors for secondary O2s and fuel tank pressure sender.

If you're going to use an aftermarket harness, I highly recommend you have a stock harness available to you that you can cannibalize. I ended up adding several more wires, which requires the correct pin at the end of the wire, so that you can clip them into the large electrical connectors at the PCM. Having a factory harness I could cut-up let me have those pieces on hand, and even let me keep wiring correctly color coded to aid in trouble shooting.

The LT1Swap web site was a great resource for me. Especially this page that has the complete pin outs for both PCM connectors for GenIII LS truck motors. https://lt1swap.com/99-02_vortec_pcm.htm

The Painless harness will have 95% or more of the wiring done for you, but you may have to add to it. The most notable circuit I added was the fuel level sender. Painless should have made this part of the emissions control harness, but it's not. GM designed the PCM such that it will not run the EVAP or O2 sensors tests if the fuel tank level is over 85% or under 15%. You must wire your fuel level sender to the PCM so that it has this data and can run the tests. Without this your EVAP and O2 monitors will never set.

The 1991 GM fuel sender in my tank was a 0-90 ohm unit. The PCM was designed to work with a 40-250 ohm sender. One option is to wire in a 100 ohm resistor when you wire the old style sender to the PCM. That will make it a 100-190 ohm sender, which is within the 40-250 ohm range the PCM is looking for. The problem I ran into with this setup is that your fuel gauge will no longer work. The PCM is a 5V system and your gauge is a 12V system. Not even the good ol' diode trick will allow you to use one sender to satisfy both the PCM and fuel gauge.

My solution was to modify a 40-250 ohm sender and put it in the tank beside my existing sender. It's not the prettiest looking solution, but it's hidden inside my fuel tank, so I never have to look at it. It did require drilling a hole through the top of the assembly so the extra wire could exit the fuel tank. Of course, you'll have to seal the hole very well, since the EVAP system measures tank pressure. With two separate fuel level senders, both my fuel gauge and PCM are happy, and with no resistors.

A quick note on monitors... ALL monitors must be set to pass your referee inspection. I read several places that you an pass with one monitor not set. That is either outdated or just plain bad information.

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I’m in the middle of this swap right now. I’ll be filming all of it and posting a few videos to YouTube so folks can follow suit. Hopefully I can also pass.

My question here is on the fuel sender. Why couldn’t you tee the signal from your level sender in that tank and add the 100 ohm resistor in line to the PCM and not both the PCM and gauge?

Just curious if I’m missing something here.

 

[BRetty]

Swilson143,

This was a very very informative write-up indeed.

It's odd how govenment rules and policies, when administered by very informed govt employees who seem motivated to, how can I say this, "get things done", can be strict-but-possible. Wheras you feared encountering a "referee" who would want to make you fail, who only saw their job as enforcing "rules" with no regard for helping the public (their ultimate "customers") learn about, work within, and comply with said rules.

I don't mean to thread-jack, but any discussion that is essentially about government rules and regulations, is necessarily about politics, not in the "red/blue" sense but in the sense of governance, and public benefit. It's unfortunate to have laws where the individual public servant's interpretation of the law, even maybe on that given day, is make-or-break judgement on your investment of $xx,*** in something you want to build.

To contemplate: What is unique to your "permitting" experience here, that results in semi-clear laws and good guidance from govt officials, so that you can get this done...as opposed to the opaque regulations in housing, construction, oh IDK, weed dispensaries... lots of stuff in California? Are there ways to make those things better? Or is maybe the entire point to make it impossible to do anything without bribes, lobbying, graft, etc?

I'm a carpenter, I have built furniture and restored some very $$$ antique pieces. The restrictions on chemicals and solvents in CA make that all but imposible now. ~15 years ago, the author of THE BIBLE on wood finishing, had a whole section on environmental laws, with a sub-section on California, then a sub-sub-section on Southern California, then a bit about SCAQMD. At the end, he simply said:

"It is normal to be confused by regulations." (*)

Truer words never spoken.

Political content: Is there any hope that those making regulations might try to understand the huge difficulty and cost of all this inspection and compliance? It seems like in California, the only rhetoric that gets votes is the language of justice/punishment. Lots of talk about shutting down, making them pay, silence about working things out and keeping businesses thriving, people employed, etc.

I'm not optimistic, but stories like yours and the referee (more like "coach") whose job was to get your vehicle compliant and licensed,
not tosed out and scrapped, give me hope.

BR

(*) He also wrote, "

If you are not sure what is permitted in your area, call me (or my company) and we will do our best to help you. [phone number]"

This guy instantly got my lifelong custom.

 

[JmoeVigil]

Lot's of great info. I am rebuilding a 2003 5.3 from an escalade for my 85 c10 in NorCal. Glad I found this as I am rebuilding it bone stock and have the 4l60e with it along with harness and PCM. going to be a long process and I am nowhere near being complete but this gives me hope