SMOG LEGAL ENGINE SWAP TO LS yesterday passed!
 

My son just got his CA smog cert motor swap approved yesterday from referee on his 90 GMC Jimmy. I am writing this up as still fairly fresh in my mind and don’t want to lose knowledge. We were also told his rig is first smog legal GM 90s truck engine swap to LS in Northern California. ALL BELOW IS GOOD FOR TRUCKS, SUVs.

This was almost year long process (although could have been done in month if really serious) and surprising amount of money involved. The result is he now has 2001 5.3L Tahoe motor in his Blazer he can play with. Also, better fuel mileage (16-20MPG vs 8-10MPG) and more stock HP. Once in, lots of fun things can be done with respect to tunes and add on’s (not CA legal, but a person could do between smog visits).

Choosing donor vehicle was not arbitrary; If you choose too modern, gets harder. If you choose too old, no point. He decided to shoot for 2000-2004 series motors as they represent decent version of LS motor and straight forward for smog reasons. He landed on a 2001 49 state Tahoe with 5.3L and 4L60E trans. The motor had 862 heads, make sure to look if you choose 5.3L. In retrospect, he thinks the sweet spot swap is 2002 Tahoe.

CA RULES:

Must be newer vehicle than your current one.

Must be same CLASS of vehicle (you cannot put car motor in truck or vice versa). GVWR is considered, motor must be designed to push similar vehicle (originally they said must be LARGER MOTOR, but turned out not to be true).

Any item associated with smog control MUST be from donor vehicle (trick is know what they truly are!).

IMPORTANT POINT!
You must know what version your squarebody is before you buy donor!!! California dealers, in his year, sold BOTH CA only versions and FEDERAL emissions versions of Square body. The donor vehicle MUST MATCH!!!! If you are forced into CA version of squarebody, the CA version of Tahoe had air injection that must be moved over. My son had federal Blazer/Jimmy, so he found federal (49 state) version of Tahoe in Nevada. Vehicles we considered were Tahoe, Denali, Suburban, Yukon.

To keep your life simple, GET AS A SET FROM DONOR CAR; ENGINE, ECU, TRANS, BODY CONTROL MODULE (YOU WILL NEED), AIR INJECTION (for CA version), CROSS OVER PIPE WITH O2 SENSORS MOUNTED IN CORRECT PLACES before and after each catalytic converter x2 (you will need different cats), ALL EVAP ITEMS (charcoal canister, OEM tank that will not be used, pressure sensor, purge valve), engine and transmission wiring harness all the way back to gas tank, no exceptions. ECU serial number drives everything else requirement wise, get all parts or you will play scavenger hunt hell!
All systems dealing any form with smog must be intact. In my sons case, the Tahoe had VATS system that cuts off fuel as part of theft deterrent. THIS MUST BE INTACT!. That does not mean column must be there, but the body control module will need to exist. This should come from donor car. Be advised, it will need to be hacked to satisfy all inputs including VATS, as it will throw check engine light and you will fail! My son stuffed unit under dash and installed VATS resistor and bypassed other necessary items to prevent error code. 1-wire bus must be connected back to ECU.

NEEDED ITEMS;

TIME! See my note about passing current smog before starting swap.
RESEARCH! COMMITMENT! This is far more work than typical engine swap. Make sure you know your rig and rig you are getting parts from. Take your time!

AC DELCO EP381 FUEL PUMP
VCX NANO TECH 2 SOFTWARE KIT
DIRTY DINGO AC BRACKET (allows use of R4 90s compressor), DIRTY DINGO MOTOR MOUNT KIT
4L60E TRANS from donor truck.
SPECTRE BRAND COLD AIR INTAKE CARB APPROVED
CARB APPROVED headers (will need as stock manifolds will NOT fit between frame rails).
Adaptor to connect your 4l60E to your transfer case (he had NP241C TRNSFR CASE).
New CARB approved CATS, Small enough to fit application. Lots of options, look at your actual requirements.
Fuel line converter connectors to mount old tank lines to new fuel lines.

Save yourself headache, buy new aluminum radiator! Will need extra cooling anyway!

KEEP ALL CARB APPROVED PARTS RECEIPTS AND PRINT OUT CARB APPROVED DOCUMENTS FOR EACH PART! HAVE ON HAND!
SERIAL NUMBER OF DONOR CAR!
GOOD AT WELDING EXHAUST PIPES. In the end, I hacked exhaust in just enough to drive to exhaust shop, then paid tech to piece new system together.

STEPS-

STEP 1: WAIT UNTIL YOU PASS AN ANNUAL SMOG TEST! You will want the time to ferry your rig around and time to work on nuisance issues.
STEP 2: PLAN, then buy.

NOTES:

YOU CANNOT HAVE CHK ENGINE LIGHT FOR ANY REASON!!
USE CA FUEL LINE FOR ALL FUEL RELATED ITEMS. Almost failed last run due to using vacuum line instead of fuel line for pressure sensor.

IMPORTANT NOTE ON EVAP TEST!!!! It seems that GM might have had issues with evap software in ECU for that generation; it is VERY common for evap to fail on that gen vehicle. Once can run test 10X times, get only 1 pass, and nothing be wrong. In the CA smog reference guide, evap test is not required for annual test, BUT MUST PASS FOR ENGINE SWAP!!!

ECU MUST BE FLASHED BY DEALER WITH LATEST VERSION FW, CHECKSUM MUST MATCH AND VERIFIED BY REFEREE. No cheating, it must be stock with no bypass. None.

You will need to know your engine wiring harness, wire by wire. You will need to know each pin on your ECU, function of each pin and how it connects. You will need to put power and ground on dozens of pins on your ECU.

O2 SENSORS IN EXHAUST; these must be mounted in similar location to OEM, and MUST be same distance from engine as OEM. 4 total, there are 2 on each side of engine, before and after each CAT.

The OEM crossover will not fit on your squarebody, too wide. Have exhaust shop put whole system together. Cost me $200 to have all done for me (not including parts I bought), not worth my time.

Cold Air intake: Rules say that intake must be for donor vehicle. OEM air box simply will not fit! He found SPectre CARB APPROVED version cold air intake, we found would not fit on passengers side. After anguishing about it for hours, we found we could mount it up-side down and fit on drivers side. Had to weld bracket to make it work. Referee examined this quite a bit and called supervisor, ruled to be OK. You may not modify ANYTHING AT ALL FROM ORIGINAL CONFIG.

Frame rail will need to be notched slightly to fit header in; right around EGR mounting point on passenger side.

Lots more detail, will post as time permits…

If you get into this and find yourself in trouble, you can email me. steve.vangent@att.net

Re: SMOG LEGAL ENGINE SWAP TO LS yesterday passed!
 

ALSO; The transmission MUST be controlled by ECU to pass smog-I.E. must be from donor and be engine/trans as a pair.

Re: SMOG LEGAL ENGINE SWAP TO LS yesterday passed!
 

That is an impressive write up. I don't know how this hobby still exists in your state.

Re: SMOG LEGAL ENGINE SWAP TO LS yesterday passed!
 

Nice! do the E-rod crate engines fall under the same class of car or truck engines as a donor.

https://ww3.arb.ca.gov/msprog/afterm...o/d-126-30.pdf

Re: SMOG LEGAL ENGINE SWAP TO LS yesterday passed!
 

Yes, E-rod is an option, not cheap ($10K -ish) and almost sample level complexity;

Re: SMOG LEGAL ENGINE SWAP TO LS yesterday passed!
 

This is why I’m so happy I have a 74

Re: SMOG LEGAL ENGINE SWAP TO LS yesterday passed!
 

@stevevangent Which ref did you go to? I’m assuming one near Redding.

We are just starting a 5.3 swap from a clean 2003 Yukon into an ‘86 shortbox with California emissions. Trying to piece back together the 80s computer controlled carb setup looks to be a nightmare so swapping it is. On the ‘03+ trucks and SUVs it is DBW and California emissions models no longer have air injection.

Interesting to know about the VATS setup. We were unsure whether the ref would allow VATS to be disabled in the ECU, so was going to hack together something to keep it all intact anyway.

Re: SMOG LEGAL ENGINE SWAP TO LS yesterday passed!
 

Excellent info for anyone choosing to be suppressed so heavily by a state.

Re: SMOG LEGAL ENGINE SWAP TO LS yesterday passed!
 

Do you think what you spent on doing the swap your way versus purchasing an E-Rod engine kit is a better route money wise?

Re: SMOG LEGAL ENGINE SWAP TO LS yesterday passed!
 

People let’s keep this thread focused on actual information about LS swaps that pass the California engine swap guidelines. My choice of living in California has a lot more factors than how cheap I can have one of my hobbies. Telling us that you don’t live here, and somehow tying that choice to the emission laws of this state, doesn’t add any value.

Re: SMOG LEGAL ENGINE SWAP TO LS yesterday passed!
 

Thank You! :metal:

Re: SMOG LEGAL ENGINE SWAP TO LS yesterday passed!
 

The Almighty one strikes again!

Re: SMOG LEGAL ENGINE SWAP TO LS yesterday passed!
 

Thanks for posting all that info, I'm sure it'll help someone thinking about doing the same thing in the future. How did you guys handle the fuel tank pressure sensor? I had an '89 Blazer and a wrecked '01 Yukon that I was planning on swapping drivetrains but that was one of the hang ups with the emissions part of the swap that turned me off that idea. I wound up selling the '89 Blazer and bought a '84 diesel Blazer (smog exempt) just to avoid all of those headaches lol.

Re: SMOG LEGAL ENGINE SWAP TO LS yesterday passed!
 

It looks like Steve van gent went with the '87+ pump module with EP381 route, so I'm not sure how he hooked up the EVAP to that system.

We are going to actually use the entire '03 Yukon fuel pump module and sender and modify a fresh tank to accept the wider module. So some fab work on the tank with the tradeoff of having a complete factory fuel and evap setup.

Re: SMOG LEGAL ENGINE SWAP TO LS yesterday passed!
 

Yeah I saw him mention the EP381 pump so I was assuming he used the stock TBI hanger/sending unit as well which had me curious about the EVAP stuff. I was planning on swapping in a newer sending unit like you mentioned since it's all self contained but besides having to modify the tank to fit the newer style sending unit (check out vette works for the adapter flange if you haven't already) you also have to modify the height of the newer assembly (NastyBuzzard showed why and how to do that part in his build thread a while back) and I wasn't sure how that would affect the fuel reading with the float not going through it's full range since that also affects how the ECM tells when to vent the purge solenoid, at least as I understand it... To be fair that might not have caused a problem at all but I didn't want to go through the trouble of making everything fit only to find out there's a problem and have to drop the tank again and figure something else out.

Re: SMOG LEGAL ENGINE SWAP TO LS yesterday passed!
 

It looks like NastyBuzzard was using the module out of a 20ga pickup tank which is much taller than the Tahoe/Yukon tank. We have a new '87 16ga baffled square body tank and a new '03 Yukon pump module and comparing them side by side the heights are close but hopefully workable.

Re: SMOG LEGAL ENGINE SWAP TO LS yesterday passed!
 

Sounds like you're lucky enough to have found a winning combo on the first shot which is great news for anyone else that comes across this thread. I'm using a taller 31 gallon Blazer tank and would have had the same problem NastyBuzzard ran in to. There are a lot of fuel pump modules out there that could work (car, van, truck, SUV, etc.) but I could never find anywhere online or in person that listed their heights to see which one could work and didn't want to drive my local parts store crazy ordering and returning them until I found one that worked lol.

Re: SMOG LEGAL ENGINE SWAP TO LS yesterday passed!
 

SOrry, been tied up at work- Butte Jr college is nearest ref;

Re: SMOG LEGAL ENGINE SWAP TO LS yesterday passed!
 

Probably with trans rebuild, all exhaust work, HP tuner (needed to diag issues), all-in probably about $3500 plus many hours. Some of this was due to mounting issues like width of OEM engine vs original space, engine mounts, A/C mounting issues, purchase of 12 different serpentine belts, etc.

However, I am sure the kit is not completely pain free or labor free;

Re: SMOG LEGAL ENGINE SWAP TO LS yesterday passed!
 

Pressure sensor we originally put next to charcoal canister under hood (we put the Tahoe canister in gap behind left headlight), then moved to filler neck return in rear thinking it was corrupting the test results. My theory was that the sensor should be able to be anywhere in the line between canister, tank, filler, etc-in the same 'void'. seems like that is true. What is VERY disturbing is that the evap test itself is riddled with bugs (which is why it is not required to pass on year to year testing) and must be patient and force vehicle to keep trying to run and pass test. We bought GM deal tool and forced test to run. Kept trying and trying. Many fails, only passed 2X times. Once it passes, fill tank to brim to prevent test from re-running before ref test!

Re: SMOG LEGAL ENGINE SWAP TO LS yesterday passed!
 

Good choice; Had we found that we would have used it. We did buy a high flow pump to get pressure way up;

Re: SMOG LEGAL ENGINE SWAP TO LS yesterday passed!
 

Yes, we had that issue, we used a Muxwiring module; it has a user adjustable look-up table that we 'tuned' the reading to match the actual level in tank. This feature can be used on the module to read any analog reading that is not normalized or linear to another input and adjust it to fit needs. pretty slick. We then used a decade resistor box to send all possible resistance values and real-time adjusted the look-up table to match requirements while watching reading on Tahoe ECM.

Re: SMOG LEGAL ENGINE SWAP TO LS yesterday passed!
 

The firmware and tuning in ECU MUST be exactly as OEM rig- you may NOT turn off VATS with tuner! They will check! This adds complications; for example, the resistance value of the fuel level sender is easy to change in ECM with tuner, but NOT ALLOWED! the ECM checksum must be from written document from OEM. Any tuning changes will change checksum.

ALso, the VATS system resistor value in ignition key is read VIA the body control module and sent to the ECM over GMs proprietary com bus.

Never fear however, if the body control module came from donor car, actually just becomes wiring exercise. Once you find the ignition key resistor value, just hard-wire a fixed value resistor to body control module.

Re: SMOG LEGAL ENGINE SWAP TO LS yesterday passed!
 

How much did this cost you to get to this level?

What fuel tank is in the truck?

Re: SMOG LEGAL ENGINE SWAP TO LS yesterday passed!
 

Motor / power plant from donor Tahoe with all parts was $1500; All in was about $6000 including trans rebuild and all exhaust work, drive shaft, motor mounts, etc;

OEM fuel tank in truck. No change.

Re: SMOG LEGAL ENGINE SWAP TO LS yesterday passed!
 

What dose this mean for running a manual transmission? If the engine/trans donor has a manual trans it should be ok, or dose it have to be a computer controlled automatic? Also would that mean that only a 4.8 or 6.0 be used? As the 5.3 never came with a manual.

Re: SMOG LEGAL ENGINE SWAP TO LS yesterday passed!
 

Presumably you're correct.

The original poster mentioned that the ECM coding had to be 100% stock in order to pass. Manual conversions require software tuning, otherwise they set the "check engine" light(another no-no) at a minimum.

Re: SMOG LEGAL ENGINE SWAP TO LS yesterday passed!
 

WOW. Glad I live in NY (can't believe I just said that!) You can put anything you want in a pre 96 car. 95 and older are safety only inspections. But then again you don't see many 30 year old cars on the road except on a weekend in the summer. Buddy put a crate 454 in a 95 Camaro . Just a PCV valve with a carb .

Re: SMOG LEGAL ENGINE SWAP TO LS yesterday passed!
 

Look up a VIN in the donor engines' model year with a manual transmission. They were available on the GMT800 chassis trucks.
Then re-code the PCM with a J2534 passthrough ( I use a WiFi MDI clone ). You use that VIN with a single VIN license in the web applet at the AC Delco TDS web page. Program as a replacement PCM and it'll dutifully program your PCM with manual transmission parameters etc for that VIN.

Re: SMOG LEGAL ENGINE SWAP TO LS yesterday passed!
 

the trans thing is crazy how the hell does that make a difference in emissions. fuel economy possibly if you kept say a th350 or 400 but emissions aren't going to change. I wonder how they deal with replacement engines on stock cars or say if this engine failed can you just swap in another 5.3? so many more things I wonder but im in ky so no point in me asking.

Re: SMOG LEGAL ENGINE SWAP TO LS yesterday passed!
 

The PCM expects to get feedback from sensors in the automatic transmission.
If you have an LS with the ECM TCM setup the ECM expects to get feedback from the TCM.
If the ECM or PCM doesn't get feedback from the TCM or transmission in response to its' requests it gets lost. Some ECM/PCM will drop you into limp mode and others just plain freak out.

Harvey Hardway would brute force it with a tuning package. You run the risk of missing something minor that'll freak out the ECM/PCM in some obscure manner if you try to be Harvey Hardway.

The easiest way to handle running a manual transmission or an older automatic transmission on a modern engine is to program the PCM or ECM using a manual transmission vehicle VIN and then fine tune the settings with your tuning package.

The fuel and spark tables from a 3/4 or 1-ton truck may be advantageous as well.

Re: SMOG LEGAL ENGINE SWAP TO LS yesterday passed!
 

I get that but it still doesn't make sense it has to be original same with the motor. so if he used a 4l80e which is totally doable he would fail or used a 700r4 which also is doable would fail. he cant retune it from the sounds either and delete or reprogram these things to work with one another. even if the engine is not creating any more emissions than it would stock. so on that token I wonder if he could use a 4l65e instead of the 4l60e. not the stock set up but nothing has to be changed in the ecm. or if ran a 10 model that has a a separate tcm unit and the ecm is same manual or auto. I think cali is overkill.

Re: SMOG LEGAL ENGINE SWAP TO LS yesterday passed!
 

I don't live in cali will never live in cali so I don't want to clutter up his thread only curious

Re: SMOG LEGAL ENGINE SWAP TO LS yesterday passed!
 

The peoples republic of California is run by the un-elected pencil pushers that have their little feifdoms for the benefit of the aforementioned pencil pushers.

What they do doesn't have to make sense. If you ask... it's because they say so.

Re: SMOG LEGAL ENGINE SWAP TO LS yesterday passed!
 

Just wanted to clarify because Im planning a swap in my 79 C10, are you using the OEM blazer tank or the OEM tank from your donor? My 79 has saddle tanks that Id like to reuse but I`ve also been thinking of swapping to a 87-91 Blazer tank to keep it simple with 1 tank.

Re: SMOG LEGAL ENGINE SWAP TO LS yesterday passed!
 

You can use the 87-91 saddle tanks with the baffles and senders with fuel pumps as high volume low pressure lift pumps and a fuel pump on the frame rail to push the pressure up to LS specs. You'll need to upgrade the NL2 dual tank valve to the motorized Pollack valve. The NL2 wiring and switch will need to be updated to the 1987-91 TBI setup using the fuel system power wire from the LS ECM in place of the same from the TBI ECM. This allows you to keep your 40 gallon capacity with two tanks.
The LS ECM should cut fuel pump power as soon as the engine stops so... as long as you're switching the fuel pump power with the ECM you don't need the oil pressure switch as a safety system.

The 1987-91 Emissions and Driveability books in my manuals thread have detailed information on how the power feed from the ECM feeds the fuel pump relay and the NL2 valve power. Look up the Dual tanks theory of operation thread for more information as well.

Several European and US automobiles use the in-tank HVLP lift pump to HP fuel pump scheme for fuel supply.

The TBI pumps will push significantly more volume GPH or GPM at lower restriction/pressure.

When tanks without baffles are your only option you can put a submersible LS fuel pressure pump in a slosh can with feed and return to-from the tanks and to-from the fuel rails. It's not needed with the 87-91 TBI fuel tanks.

Re: SMOG LEGAL ENGINE SWAP TO LS yesterday passed!
 

Thanks,great Info here. If I stick with the saddle tanks I will change them to the 1987 TBI tanks but I am also considering a blazer tank conversion. My main issue is making everything smog legal. I know they need a vapor pressure sensor or something like that. Figured swapping to a single tank would make things easier. The swb saddles are only 16 gallons each so I wouldn't be losing too much and rarely filled both tanks in previous trucks.

Re: SMOG LEGAL ENGINE SWAP TO LS yesterday passed!
 

The fuel tank pressure sensor is just like an old fashioned MAF sensor. You need a bung that it'll fit through tightly.

The rest of the LS version of the EVAP system is fairly simple. If you weren't in the Peoples Republic of California you could bypass the EVAP readiness test and plumb the less expensive components from the 1970's evap canister setup to the purge valve. It would work just as well as the LS system but your overlords have no doubt decreed you shall use the LS motor evap system or else... off with your head...:lol:

Re: SMOG LEGAL ENGINE SWAP TO LS yesterday passed!
 

We generally do not mess with 1976 and newer vehicles due to smog laws.

Re: SMOG LEGAL ENGINE SWAP TO LS yesterday passed!
 

This is why I will not put an Ls in my '91 suburban. I'll go 383 or 400. They have no idea what's under the valve covers. As long as it passes visual and emissions I'm golden