How to LS Swap a GMT400 (or any other vehicle)

[MJEngineering]

How to build a LS performance platform and swap it into anything, as demonstrated by MJE
Version 1

This thread will cover every aspect of a thorough build and will hopefully answer a lot of the frequent questions I get and be a single resource to those interested in LS performance or swaps.

The vehicle demonstrated is a 1999 GMT400 truck but it could just as well be a muscle car or offroad buggy the principles will all be the same - I will try to make clear what is universal or not.

When someone says “engine” they are really just talking about a big pile of parts and depending which ones you choose will drastically change how it all works in the end. I am going to break down every element of the powertrain and all it connects with, which is why I have used the terminology “LS platform” instead of engine.


PARTS SELECTION
I think the most common question I get is “what should I do to my vehicle for performance?” The answer is opinion based. I believe I am allowed to have an opinion as I have driven, built and dyno tuned every single type of vehicle and performance upgrade there is. American, European and Japanese; 2 wheels and 4; on and off the road. I have a truly unique perspective as to how vehicles operate especially under heavy use.

If you drive a truck (and in most cases) a car on the road, one of the best things you can do to it is to add a positive displacement type supercharger. My reasoning is that the only other thing that will make your vehicle act the same way as a positive displacement blower is a massive increase in cubic inches. The extra power of a positive displacement blower is available instantly from idle and 0 throttle – it moves the entire capability of the engine beforehand to the first third of the throttle afterward. Turbos and centrifugal blowers act the exact same way the engine did beforehand until a higher RPM when the boost comes on and you're doing well over 100 mph which is an extremely bad idea in a truck and an even worse idea for public roads. The positive displacement blower will not make as much boost at 6000 rpm as the other methods but without a race track there is no way to tell or use that power. But they are no slouch, I have seen 700 horse on our dyno from positive displacement blower cars. (I have seen double that from turbo cars so just remember the sky is the limit.)

The next most popular question I get is “what cam should I run?” And my answer 9/10 times is: stock. People think that since they read online it makes more “power” that it will make their vehicle better, this is false. You're taking the same engine and just winding it to a higher rpm. Horsepower = (torque x rpm)/5252 so the same engine will make more “horsepower” at more rpm. If you want to run your engine to 7500 rpm you better have a lot more than just a cam, the entire valvetrain will need to be replaced and most likely heads and entire rotating assembly. This is again much more useful on a racing vehicle and pointless on the street, especially in a heavy truck. Torque is ultimately the best indicator of how a vehicle will run and feel and 99% of cams for LS motors will lose ~50 ft-lbs below 4000 rpm which is where you drive every day.


ROLL CALL
The next big issue is “what conversion parts do you need?” Very few, especially to get this platform into this vintage GM truck.
Conversion Motor Mounts
Conversion Stainless Steel Braided Fuel Lines
Conversion Water Temp Sender
Steam Line Fitting for Upper Radiator Hose

What are the other parts to this build?
6.0 LQ4 shortblock and valvetrain
Machined Heads, Valves, LS9 Gaskets, ARP Head Studs
Whipple Supercharger, 4” Elbow, FAST IAT Sensor, Scoop, 6” K&N Filter, Mechanical TB etc
Aeromotive Stealth Fuel Pump, 65lb Injectors
Finish Line Transmission 4L65E and Custom Yank Torque Converter, SFI Rated Flywheel, 40k Cooler
LS1 Fans
Custom 2.5” exhaust / shorty headers / Magnaflow high flow cats / ****** Aerochambers / x-pipe / 100' exhaust wrap
TrueTrac Locker, Larger Bearings
Instrumentation (Stock LQ4 Oil Pressure Sender, 99 Vortec Water Temp w Street and Performance Adapter, AutoMeter Boost, AutoMeter G Meter, AutoMeter Wideband O2, Pillar Pod)
Wiring Harness, Body, Engine, Modify Factory, Accessories
Radio, Subs, Batteries
Lighting Interior and Exterior
EGR / Evap / AC / Cruise Delete, Fuel Tank Breather, Catch Cans
Paint
Hydroboost splitter.
NGK TR6 Plugs / MSD Wires
2500 Front Calipers, Stainless Braided Brake Lines, Prop Valve, Line Lock, ABS Delete
Shocks
New Alternator
Stock LS Power Steering / LS Water Pump / SBC Motor Mounts / Accessory Bracket

 

[MJEngineering]

ASSEMBLY
Unfortunately, reading this alone will not make you a good mechanic. Time and practice makes perfect. There are elements of the assembly that will not be covered and will assume you are competent enough to fully disassemble and reassemble a vehicle.

Remove the existing engine (and if so desired trans/transfer case). If removing engine and transmission it is easier to remove the grille shell and pull the entire driveline out in one piece. Leave the factory wiring harness intact, just disconnect it and ziptie it out of the way - it will save you a lot of work later.

This truck had already been swapped by me but it was my first attempt at doing so and was not very neat. It had survived many thousands of hard miles though.

All bolts you remove from the engine or body or anything else should go into ziplocks that are clearly labeled and organized. Even if you do not plan on using them again if they are clearly labeled you can find similar size fasteners in a pinch. Keeping them sealed up in ziplocks also prevents them from escaping / rolling out of the bags while in storage / transit as well as preventing corrosion.

Either build your shortblock, have someone else do it for you or just run the stock one. For medium to high boost applications you can run the stock pistons but you should cut the rings down so they don't chip the pistons under heavy load. I am running a totally stock shortblock and cam as extra proof how stout they are while performing very well. My blower only makes 10 lbs so I am in the safe region especially since it will be tuned right. Down the road I can swap this shortblock for a fully aftermarket built and larger bored and stroked version of this engine that is ready for more boost and then later swap to a bigger blower like the new Whipple 4L. Try to think ahead, think in stages – and try not to bankrupt yourself competing with people on the internet because you will always lose.

Clean the heads and pistons and get new gaskets. Make sure to find TDC for each piston when cleaning so you don't damage the cylinder walls. I had the heads machined and reconditioned locally, they now have higher compression and flow better as well as having the valves redone so there will be no turbulence or leaking. Make sure the engine block is either also machined for best head gasket sealing or prepped in another way, in this case I lightly used a 3M rotating air tool for cleaning metal without damaging it.

I chose LS9 head gaskets from the factory supercharged Corvette, they are stronger than the other factory head gaskets but fit this engine perfectly and are known to seal better to non-machined surfaces (my block). Seal them with Permatex head gasket spray. You cannot reuse the factory head bolts so ARP Studs were used for the extra clamping under high load. Before installing them, chase the threads on the block. To make a thread chaser take a stock head bolt and cut 3 or 4 grooves into it along the shank to the tip with a cutoff wheel. While you're there check the knock sensor mounts have not come loose as this will make tuning more difficult down the line. I installed a new oil pan gasket and there was no leaking from the front cover so it was left alone. Put a drop of RTV in the corners of the oil pan where it meets the timing cover and rear cover to help prevent oil leaks.

Follow ARP's procedures for torquing the heads down, +5 ft-lbs for a boosted engine. If you have the luxury of time, torque fully then loosen and retorque the next day or next week, etc several times to fully stretch and seat those studs which you do not want to have to do with the engine in the vehicle. Don't let the heads lift or you will ruin the seal from the gasket paint.

Once my longblock was buttoned up I taped it up and painted it. First in a high temp red, then with a red glitter paint that matches the rest of the truck's accents, finally with a high temp clear. Each step consisted of about three layers, the clear was several more than that. This process was repeated on the intake manifold, the water pump and the accessory bracket with power steering pump.

The intake, injectors, old alternator, idler pulley and water pump get cleaned and installed with a fresh coat of paint and all new gaskets. Before installing the valve covers, pour engine oil all along the valves and pushrods to help with start up oiling.

The Whipple supercharger was returned from Jon Bond Performance (https://jonbondperformance.com/) with upgraded ceramic bearings, an upgraded bypass and port/polish the insides. Coils and harness make an appearance for the first time.

The transmission is from Finish Line Transmission (http://www.finishlinetrans.com/) and was reconditioned and upgraded to their 2013 spec this spring as it was originally built for the first iteration of this vehicle in 2009. It utilizes the absolute best components available for this type of transmission as I did not want to switch to the 4L80 as (in my opinion) they are extremely heavy and slow, again going against the hyperactive instant throttle response I was looking for in this vehicle. The converter is a Yank (http://www.converter.cc/), about 2800 stall with lockup, custom built for my application and mates the SFI rated LS1 flywheel to the transmission with no other conversion pieces needed. The crank at the back of the block was about half an inch longer or shorter depending on the year and model of the engine in question, for those people running stock transmissions you will need either the right flywheel, transmission or torque converter to make it work. If you have specific questions you can always ask me and I can check my reference charts.

The converter is one of the biggest differences in driving from a single part so one that is matched to your application and desired driving style and use is critical. Remember to put a quart of ATF (for a 4L60E, a 4L80E requires more; check with your trans builder) in the converter before you install it. You will have to pour just a little ATF in at a time and let it sit to get a whole quart in most converters. To install the converter, gently place it on the input shaft of the trans as centered as possible and spin it several times to the right and left with your palm providing pressure on the mounting surface. If it clicks inward three times then it is correctly mounted. If you go to install the transmission to the flywheel and engine block and it seems like it is not going to fit, do not force it as you can break many expensive parts in a matter of seconds. Remove the transmission and converter and try it again, worst case scenario you can measure the distance from the converter surface to the engine mounting surface and compare it to the block to flywheel surface measurement. Too little or too large of a gap will require mods. With a modest gap you can add washers to space between the flywheel and converter but I am not a fan of that for high horsepower builds. I have even heard of (but not done) drilling the flywheel holes open a bit more to fit a different converter for those on an extreme budget. Use Red LocTite on the bolts that fasten the converter to the flywheel.

 

[MJEngineering]

On the topic of cranks – the largest single mechanical difference and hurdle to overcome and for tuning and getting a swap engine and computer to run between a LS1 style engine and the newer LS2+ (~2006+) style engines is that the crank sensor uses a different number of teeth. Yes the LS2+ engines have improvements all across the board but when performance swapping engines you can run the LS2+ style engine on a LS1 computer for simplicity and you would be surprised how similar the programming is. To run a LS2 engine on a LS1 type computer you can get a crank trigger resampling box from Lingenfelter Performance. I have worked with these and they do their job but they are sensitive to voltage and grounding and can cause inconsistent starting. All piggyback devices like this can be great and useful but you can end up cursing them when you're stuck on the side of the road because of a bad wire, etc. The other option is to physically remove the crank sensor from the crank and insert the one that corresponds to the computer being used. This process requires tools that are out of reach of most home mechanics and should be done by a knowledgeable machine shop. This is the only way to conversely run a LS1 style engine in a LS2 style car on a stock GM E38 computer aside from swapping the entire crank, etc.

The motor mount adapters are from Street and Performance (http://www.hotrodlane.cc/) they are nice billet aluminum ones but steel ones are available from many sources. They bolt on to the block and allow the factory small block Chevy clamshell mounts to be used as well as locating the engine and transmission in the proper place so that you don't need to move the crossmember. Mine move the engine backwards about 3” as that is roughly the length difference between the SBC and the LS with most of that space being taken up on the SBC by the distributor. For vehicles with unusual measurements there are mounts like the Dirty Dingo conversion mounts which allow you to slide the engine forwards or backwards several inches to match the rest of your driveline or space requirements. Use LocTite on all the engine mount bolts.

---------- Post added at 05:19 PM ---------- Previous post was at 05:18 PM ----------

Brought the truck home from the dyno to peck at the details in my off hours as I knew I would be spending weeks chasing every detail to the level I wanted.

You can install the harness before you drop it in the vehicle or after, I have done it both ways. I ended up pulling the harness completely off again on this round even though I had it on when I installed because I chose to mess with a few things so I would say skip the harness install beforehand. Also watch the coils, fuel rails and MAP sensor they are very fragile.

The engine bay was scrubbed and painted and cleaned and several things were removed. The AC system, the cruise control system, the evap system, clutch fan and shroud, abs and lots of wiring. The idea on the first build was to get the setup in and running and this time around now that most the bugs were worked out I wanted to make it look as clean and nice as possible. At least, that is under the hood - the body and general appearance of the truck is quite rough.

The factory has a temperature sensor mounted inside the MAF which would be installed in front of the supercharger. The air temperature that was actually going into the engine after being compressed in the blower would be an unknown. The more accurate the data about the incoming air temperature, the higher quality the tune can be. This setup will also be running no MAF which means an air temperature signal must be acquired from somewhere else.

The Whipple kit originally came with two injectors mounted in the intake elbow and a computer that turned them on. There are a lot of negatives to that system and I never had it connected. This time I drilled out the injector mounting holes and tapped them, allowing for a heavy duty FAST LS1 type intake temp sensor which will not leak under boost. The other hole was plugged and will be a perfect location for methanol injection later on, especially since this is a non intercooled setup.

The MAP sensor was a little loose and factory manifolds sometimes leak under boost so we fabbed a small bracket that holds it firmly in place while looking nice.

The header bolts were grade 10 units I got from Briarley Lumbard, a local machine supply shop which is extremely cheap compared to a big box store and has every fastener imaginable in the strongest grades. Many fasteners were sourced for this build from them. The headers were already fabbed from the previous build so they were painted in high temp black then wrapped. Wrapping is very tedious, requires two people and a lot of planning. Set aside several hours especially for tight tubes like mine has. Soak the wrap in water beforehand and it will be much easier to work with. I used wire to wrap and lock the collectors, lock twisting with my Klein sidecutters, the perfect tool for the job. After fully wrapped let dry for a day or more in the sunlight. Then paint several heavy coats of high temp clear. This will keep the fibers together during install and over time. Really let the paint soak in when doing this step. Let dry in the sun for a day or more.

I am using a mechanical throttle body, which is again a big benefit to creating a setup that has instant throttle response and feel. It is also a direct swap with the truck to the throttle body. This setup flows more air than the factory MAF is capable of reading, the MAF is also a restriction on the intake and for the type of tuning I will be running the MAF must be disabled. So for those three reasons the MAF has been removed and the new temperature sensor has been pinned to the proper locations on the PCM. There is a 4” diameter 45* silicone elbow on the throttle body, an industrial HVAC reducer which bumps the 4” to a 6” diameter with a 6” K&N filter. The filter is housed in a box which I fabbed from sheet metal, screws and rivets. Once formed the box was covered in Dynamat to keep down noise and to cover the rough edges. I also cut through the fender and attached a cheap stick on scoop but used screws to attach it. The front grille was also cut and a screen added in front of the air inlet duct to the fender.

 

[MJEngineering]

Ebay catch cans were installed using proper evap vent hose. The cans come empty so the trick to make them effective is to disassemble and stuff them with three bath puffs. The puffs turn into a long skinny tube once the string in the center has been cut. Each can holds one and a half puffs, stuff them in with a pencil; you will have to really cram it full. This will allow the cans to actually act as a filter.

For boosted LS vehicles I suggest the NGK TR6 plugs, which is what is installed here. Naturally aspirated LS vehicles should run TR5 plugs. This setup also has MSD wires and factory coils. The wiring for coils and injectors is tucked below the fuel rails as cleanly as possible.

I am running Delphi 65 lb injectors which are a direct match to the factory ones so no mounting or wiring changes were needed. The fueling is a return style system, there are stainless braided adapter lines with AN fittings from the factory LS rails to the factory truck hardlines. The fuel pump is an Aeromotive Stealth pump which delivers much more fuel than the factory one ever could yet easily installs in the factory pump sender. A high power pump like this gets its own dedicated and larger gauge wire run from the pump relay to the pump itself, and a higher quality ground. The operating system the PCM is using outputs the reported fuel tank level via serial data to a semi-digital dash so there is no way to integrate this into my 1999 full analog dashboard. I have the fuel level input to the LS computer and I can see the fuel level via my scanner if need be. The other option would be to run an auxiliary gauge. Earlier vehicles should not have this problem as they had mechanical not computerized and calculated fuel level gauges. I solved the problem by typically filling the tank full each time and resetting and using the trip odometer as a fuel level indicator.

---------- Post added at 05:20 PM ---------- Previous post was at 05:20 PM ----------

The entire EVAP system was removed. The hole on the intake was tapped and plugged. The charcoal can was removed as well as all the lines. At the fuel pump a short rubber line with a small fuel filter was attached to the old EVAP port.

LS crank pulleys are pressed on, with enough accessory load they can spin on the crank, becoming useless or damaged. This heavy load is created by the supercharger and so the following should be done on all supercharged vehicles. Remove the crank bolt, install drilling alignment tool or in a pinch you can do it by hand. Drill about half an inch or a bit more into the crevice between crank pulley and crank. Cut that exact length off the drill bit used to cut (or what came with a crank pin kit) but no longer because there will be no easy way to remove it and it will not allow the crank bolt to sit flush. Place the pin in the drilled hole. Drill 2 holes for a very heavy duty application. Reinstall crank bolt.

The grille shell, radiator and 40k trans cooler were cleaned and painted. Transmission coolers should be flushed with a can of trans cooler cleaner available from any auto parts store. LS1 fbody fans were mounted upside down and wired up with two 30 amp relays triggered from two pins enabled on the computer via EFILive. The relays have fused hots to all pins except one side of the relay; the coils which are grounded/switched by the PCM. The lower rad hose is a factory OBS one that fits fine with a little trimming. The upper hose is a NBS hose that was cut. The supercharger relocates the upper hose anyway so a 90* coolant line end is on top of the water pump and joins the NBS hose with a steel tube with a small fitting T welded into it which via rubber line leads to the factory coolant bypass or “steam” lines. The steam line going to the throttle body was disconnected and the throttle body steam vents were blocked off by routing one to the other.

The 6.0 came out of a vehicle that had hydroboost brakes, this means that the factory manifold did not have a port for vacuum brakes like this vehicle has. GM still included a port on the manifold for such a purpose but it is blocked by a quick release plug on these engines. GM offers a proper nipple part for sale that neatly slips into the plugged port at the back of the manifold and is sized properly for a GM vacuum brake booster such as this truck has. 5.3L, 5.7L or 4.8L motors will have a vacuum port from the factory. To remove the plug or vacuum adapter from the rear of the intake, press the little circle clip with a flat screwdriver and it will unlock the plug and it will pull out with minimal pressure.

If you want to spend a bit more on the build it is a good choice to convert the vacuum booster on the vehicle to hydroboost. Hydroboost brakes do not use engine vacuum for boost, they use the output of the power steering pump. This will provide a strong pressure assistance when you have low vacuum from something like an aftermarket cam or a very heavy vehicle like an extended wheelbase 4x4 with lots of accessories. This is an off-the-shelf swap for trucks as you can just order or find over the shelf stock parts from a ¾ ton 3500 or 2500 (master cylinder, brake booster, high pressure lines from power steering pump to brake booster and rubber return line, as well as brake pad and pedal from a 2500HD truck). For cars this can be a little trickier and I would suggest checking literature or forums for your specific swap vehicle.

I am running a stock hydroboost power steering pump which has two return fittings with a vacuum style brake system for the time being. The first time I set this up I installed a simple block on the unused return fitting on the power steering pump. This setup leaked all the time even though I messed with it several ways. For this build I put together a 3/8” T fitting from over the counter parts at the local NAPA. This T fitting inputs the return from the power steering box and split the output to both available ports on the power steering pump using high quality transmission fluid rated line. It has not leaked or otherwise incorrect behavior.

For this build as a mild upgrade to the brakes I am using a NBS (2003) style master cylinder. This will work to reduce pedal squish. All the OBS (88-98) cylinders were designed for rear drums whereas the NBS unit for 4 wheel disc brakes. If you do this swap make sure you get the 1500 1/2 ton cylinder as the 2500 one is meant for hydroboost. A spotters guide is that the half ton one is slanted front to back whereas the hydroboost one is even height from front to back. The ABS was mechanically removed and a 4 wheel Wilwood brake proportioning valve and line lock for the front were installed. Rear brakes will be converted to disc soon; most likely twin caliper, one for the brake pedal and another for a hydraulic handbrake. This will help initiate sliding and control the vehicle during racing. The rear will be lowered and traction bars will also be added. I will use the same calipers I did on my other truck; 1985 2500 4x4 GM truck with brackets I can get cut locally and simply weld to the axle. Disc rotors will either be 88-98 12” or new Escalade 13” depending on final measurements.

For every system great care was taken that it not come loose with lots of vibration, start to wear through from vibration, that it not be exposed too greatly to the elements and that there is no way it can touch a hot piece that can melt it and cause it to fail. Every bolt that can be should have the final torque checked after putting miles on the vehicle, several times if possible. If something comes loose, LocTite, Lock Washer or Teflon tape it. Places and fasteners where two or more different types of metal are brought together should usually use Anti-Seize gel as otherwise they will corrode together and require being drilled out etc to be removed later.

 

[MJEngineering]

WIRING
One of the best things about working with a LS1 style (99~04) computer is the ease of setup for a standalone system. You can swap operating systems on the computer to meet your needs quite easily. I am running a truck operating system on my computer and the wiring I will discuss will mostly be specific to that, but the principles would be the same if you were running a fbody, Corvette, standalone or other system.

The engine harness will be quite large and overwhelming to beginners but I assure you is nothing that cannot be managed with time and patience. You will be very glad to know how it works when you are done, that way you will fly through any repairs necessary down the road.

The best way to think of a computer controlled vehicle is that the control units simply manage a whole lot of inputs and outputs. The good news for LS1 owners is that most of those inputs and outputs are all on the engine so that they are a self containing system that does not extend out into the rest of the vehicle much. The newer systems (LS2+) do integrate the other functions of the vehicle in with the engine computer (and communicate via unusable serial data) and vastly complicate the installation of the engine in a different vehicle. The control unit just decides what to do with the inputs and the outputs will hopefully create a condition for the engine to run optimally. On a non-electronic engine these inputs and outputs will be managed mechanically, using things like vacuum control and levers.

So what are all these inputs and outputs? This is a list of the essential parts; there are emissions and other systems (like ABS) that will be integrated but usually can be easily disabled and are not included or elaborated on this list. To have an engine swap vehicle operate as well as a factory built all or most of these systems must be working and properly tuned.

- Electrical Inputs
MAF / MAP
WATER TEMP
O2 SENSORS
KNOCK SENSORS
THROTTLE POSITION SENSOR
VEHICLE SPEED SENSOR
BRAKE / (AND CLUTCH SWITCH)
CRANK / CAM SENSOR
AC
START / RUN
FUEL
SHIFTING / TFT / TFP / RANGE / PN
EMISSIONS
FLUID LEVELS

- Electrical Outputs
COILS
INJECTORS / FUEL PUMP
IDLE AIR CONTROLLER or ELECTRONIC THROTTLE
ENGINE COOLANT FANS
SHIFTING / PRESSURE / TCC
4X4 AND TCASE
INSTRUMENTATION
AC
(ALT)
EMISSIONS


Which ones are external to the engine?
POWER / START / GROUND
BRAKE / CLUTCH
FUEL PUMP / LEVEL
AC SWITCH / POWER
ELECTRIC FANS
4X4
INSTRUMENTATION: TACH / SPEEDO / MIL

 

[MJEngineering]

How do I build the harness for my platform?
Use the harness that came with your engine when you bought it. That will save you the most time and money. If you are unhappy with the quality of the harness you have you can buy another used one or a new standalone one meant for hot rodders. If you do buy a new one make sure it has new everything so that you get your money's worth (skilled labor, copper and connectors are not cheap) otherwise you will just be getting another one of what you already have.

Each sensor or connector will have a group of wires that runs together to the computer. There are several types of sensors, usually with anywhere from 1 to 5 wires going to them. These wires carry power and other electronic or data gathering feeds to the sensor and return the information back to the computer usually by exhibiting a different voltage than what was sent out to the sensor initially. This difference in voltage is interpreted by the computer and calculated to become the value associated with that sensor. With our tuning software we will calibrate these raw voltages to perfectly represent real-world measured data in regards to whatever metric the equipment is regarding.

Disassemble the harness you have down to the bare wires so that you can inspect them and route them in a more visually pleasing way than the factory did. You will also be removing a great deal of wires as there is no need to run emissions and factory idiot light wiring on a custom or racing vehicle. Once you have the harness down to the basics you can see how each connector or sensor has its own wire bunch and you can combine these bunches and route them carefully and ziptie and loom them or shorten / extend them to your heart's content. Just be sure to properly connect them if you do.

-How do you connect wires for an automobile so the connection can be counted on?
Do not use wire nuts on a car – ever.
Strip about 3/4” off the insulation of both wires.
Split the copper into two halves for each wire (four if it is a very large one) and twist these sections clockwise.
Hold the wire bases together and twist together the copper sections clockwise, split like a Y tie the 4 ends down to 2 and then twist the 2 ends to 1 – always clockwise.
Soldier this joint for maximum connection life.
Tape electrical tape (3M or better: throw away the generic stuff – it flakes off after a year and gets everything sticky) around the base of the two wires tightly.
Fold the copper connection over onto the newly taped insulation, and tape over it carefully, tightly and repeatedly to make it waterproof.
For maximum strength, fold over again and tape the folded piece again. This will help to seal it from the elements and to prevent it from ever pulling or vibrating apart.
Cut the tape instead of pulling it until it snaps so that it doesn't unwind after a day or two and look bad.

How and where do you locate the proper wires?
If you are lucky enough to be working on a Vortec 96-99 truck like this or a handful of other GM models from the late 90's early 00's, the wires you need will all be sitting right where you need them already crimped to the appropriate fitting pins for a LS1 computer. This is why I said not to cut anything yet and to just leave the stock vehicle harness intact during disassembly. The TBI and similar vehicles will be also easy as they have pins which can also be used but less sensors that directly carry over. (But most of their sensors go directly to the dash so their swap is even easier.)

Included for example are the pinouts to my truck operating system engine harness and the factory 1999 engine harness:
02 6.0 4X4 4L80 PDF
http://tharf.com/techpdf/02_60_c1.pdf
http://tharf.com/techpdf/02_60_c2.pdf
99 5.7 4X4 4L60 PDF
http://tharf.com/techpdf/99_57_c1.pdf
http://tharf.com/techpdf/99_57_c2.pdf
http://tharf.com/techpdf/99_57_c3.pdf
http://tharf.com/techpdf/99_57_c4.pdf

http://tharf.com/techpdf/ for a lot more diagrams

Look at the pin out like above of your model year computer. Look for any things that would carry over to the new computer. One at a time, disassemble each of the four (or whatever) PCM connectors are on the vehicle. Remove each one of these from the vehicle's original PCM connector and tag them with their full name, original pin number (printed on the connectors) and destination pin as listed in the tech documents. This includes:
START / RUN / HOT / GROUND / ACCY POWER
UNDERHOOD AND UNDERDASH FUSE BOXES
STARTER / RUN POWER DIRECTLY TO STARTER FROM IGNITION IF LOCKED OUT
CHECK ENGINE LIGHT / TACH / SPEEDO
VEHICLE SPEED SENSOR
O2 SENSORS (O2 Sensors designated as Sensor 2 or Sensor 3 are for emissions and not needed. Do not confuse with Bank 1 and Bank 2 which means driver and passenger sides.)
TRANS RANGE / FLUID TEMP / PARK NEUTRAL / TCC / BRAKE TRIGGER / …
FUEL LEVEL INPUT / FUEL PUMP RELAY
4X4 INPUTS AND OUTPUTS
AC INPUTS AND OUTPUTS (IF EQUIPPED)
COOLANT FANS (IF EQUIPPED)
CLUTCH SWITCH AND SHIFT LIGHT (IF EQUIPPED)
IAT (IF EQUIPPED: The Vortec SBC uses a 3 pin MAF and 2 pin IAT but the stock IAT sensor is not good at staying sealed tight under boost.)
WATER TEMP (IF EQUIPPED)
ALTERNATOR HOOKUP (IF EQUIPPED)
OIL PRESSURE (IF EQUIPPED)

What are the wires not on the engine computer harness? These mostly go to other vehicle body computers, circuits, or to the dash directly.
ALTERNATOR
4X4
OIL PRESSURE
WATER TEMP
POWER
PARK / NETURAL / RANGE

How do you install the wires / repin?
To make your installation look and work like factory we will actually disassemble the connectors that screw into the PCM.
Disconnect battery if it is not.
Remove the connectors from the computer if they are not already. (7mm)
Remove the plastic wire management bits if they are there still. (Old ones might need to be broken off.)
Carefully using a pick push in the tab on each end of the colored pin lock on the end of the harness connector. Only do one at a time so nothing catastrophic can happen to the arrangement and that you do not confuse which color connector you are working on while being very careful not to let any pins come loose, misaligned or half inserted during the process.
To remove a pin that is installed, with a pick you will lift the small white tab which is locking it in place while gently tugging on the corresponding wire. The pin will slide out easily, do not force it.
To install, simply find the correct pin number as printed on the back of the correct colored connector (red or blue).
Remove all the emissions pins from the LS1 harness. If you are using a 4l60 with your LS engine and the vehicle you are working on had a 4l60 then keep the factory transmission pins and swap them into the LS harness. If you are using a 4l80 then use the transmission pigtail harness you have (assumedly a 6.0/4l80 takeout).
Refer to the above list for the rest of the factory pins that should be installed into your LS harness. Remember if you have the right pins you can just install them directly, no cutting or splicing required.

How are the EFANS installed and controlled?
The fans are LS1 fans so they are from the same vintage as everything else in my setup. With EFILIVE I can turn on the fan control in the LS1 computer I am using which is otherwise left disabled in the truck operating system I am using. Some people choose to run one output but I chose to run two, one for each fan connected. This is selectable in the tuning software. The PCM will ground out:
CONNECTOR 1 BLUE PIN 42 LOW SPEED FAN
CONNECTOR 2 RED PIN 33 HIGH SPEED FAN
Those pins become grounds (which should be hooked to your fan relays) depending on temperature controls set in the tune, mine is set to run at 180* engine coolant temp all the time, temps above that tend to contribute to excess intake and combustion heat and temps below that do not allow full piston ring sealing. I wired the fan opposite of the intake side of the engine to be the low speed fan to avoid blowing hot air on my air intake.

 

[MJEngineering]

TUNING
Software
The first thing you have to do tuning wise is install an operating system that correctly matches your harness and intended use. Mine is running a truck operating system that is the correct version that allows me to run EFILIVE Custom Operating System version 5. This allows for me to have full control over my spark timing and fueling in the boosted operating system of the engine – which is something you cannot do with the stock computer or operating system.

The second critical step for tuning this vehicle is something known as a transmission segment swap. Since the base operating system used was for a 6.0/4L80 and the harness is wired for and to a 4L60 the tune must match. A similar operating system vehicle (5.3/4L60) is loaded into the computer for comparison and all the relevant transmission data is carried over to create the proper vehicle controlling tune. (Again, a snap thanks to the EFILIVE software.)

Thirdly, the factory LQ4 1 bar sensor has been replaced with a GM 2 Bar sensor. The factory sensor cannot read pressure into boost range. The two bar sensor allows to read accurately manifold pressures up to 2 bars (~30 psi). This sensor must be calibrated to report the correct atmospheric pressure to the computer.

The boost fuel ratio is very rich compared to typical driving scenarios. The system is set up to gradually ramp the fueling from lean and most efficient for cruising to the proper ratio for full throttle full boost scenarios. This system uses the O2 sensors for the lean regions and disables them for the richer ones, this is called Semi Open-Loop.

The factory MAF is not capable of reading the airflow of a highly boosted engine. The MAF also presents an airflow restriction on the intake. The MAF was removed from this system, putting the computer into what is called Speed Density mode. This mode calculates the engine airflow based only off the intake air temp and manifold pressure.

The transmission has many custom parts inside and was carefully calibrated by me to provide smooth driving when desired but aggressive shifting and pressure when needed. This is a painstaking process and several hundred tunes have been created to adjust to perfection the transmission programming. The programming was also adjusted for the aftermarket torque converter.

To set idle on a LS1 computer is a skill best approached with practice. Patience and experimentation is critical. The mechanical configuration will affect idle on all but completely stock motors and even then I find room for improvement. All spark plug and gasoline engines operate on the same principle: AIR / FUEL / SPARK. This is no different for idle. The trick to getting a custom engine to idle well is a repeating process:
Get a tune in that can drive even if it is very rough. Set the desired idle speeds higher than factory (700-1000 RPM) if you have a heavily modified setup.
If you are having trouble idling, set the open loop cold fueling to be stoichiometric (14.6 AFR) so that you can minimize flooding, fouling and possible issues. Watch what your wideband says.
Drive it or run on the dyno and tune it to get the fuel trims and airflow maps close for at least the idle area.
Adjust the base idle airflow numbers roughly by what percentage the other maps had to be adjusted by.
Idle the engine in closed loop and with a scanning tool take over and lock the timing and add or subtract final timing until the idle is strongest. Stockish engines run in the teens, cammed engines will need more.
Program the main spark tables and base spark tables to reflect the idealized timing you determined before.
Log the reported and desired airflow rates and adjust the airflow tables as needed. Remember there are modifiers on the base table so you cannot input exactly what you observe.
Log the IAC value (if equipped) and make sure it is fairly low when the engine is hot, if not then you should adjust the idle set screw.
If the idle still hunts then adjust the sensitivity of the learning for both airflow and spark.
Repeat from the beginning several more times.

Proper timing is the single most important part of making the power you want from the platform. When the spark ignites makes all the difference in how much pressure will be created in the cylinders. On a stock engine, especially the trucks - the factory uses weak timing tables. This is one of my hardest-won areas of expertise, as well as varies greatly based off many factors, so you will have to find what works best for you on a dyno or other experimentation.

Exact fueling is the rest of the equation for having the engine run well. If your front O2 sensors are good and the tune is set up for it then for most of your driving conditions the AFR will be locked out and self adjusting at 14.6:1. When you full throttle or boost the engine the fueling will need to richen up to increase power output and engine durability. Roughly WOT AFR of 12.5:1 is a good starting point for naturally aspirated gas motors and 11.5:1 for boosted. Use a dyno or a race track to figure out what works best for your setup.

Every single change from stock needs to be reflected in the computer tune or else you cannot expect factory-like operation. Dig through the software and the manuals to determine what you must do. Forums can help but I suggest if you have the opportunity to simply experiment and see what works for you – many tuning related things are neither right nor wrong, they are purely personal preference.

Hardware
Once assembled and running, many parts of the system will need checking or adjusting. For this build to get it running we needed to replace the old alternator, battery, master cylinder and adjust certain aspects of the wiring. All fluids must be checked and all bolts must stay tight. Everything that has been touched may fail and needs to be checked, topped off or adjusted.

When refilling the coolant and before first startup, do not only fill the radiator. Connect the lower hose to both the radiator and water pump and fill the radiator to the top with coolant. With the upper radiator hose connected to the water pump but disconnected from the radiator, fill the engine block through the water pump with a funnel and coolant while holding the line vertical to help the fluid flow. Also be sure to fill the overflow tank to the cold level. When the engine block will not accept any more coolant, attach the upper radiator hose and put the cap on the radiator. Start engine and recheck coolant levels in the overflow tank and the radiator after the thermostat opens.

Once the engine is idling the ATF fluid needs to be set, the level must be checked at idle in park on flat ground. Make sure you put the trans in gear/park and drive several feet if possible (even if only with wheels spinning in the air) several times each fill to work out air bubbles in the cooling system and get a true reading of level. Half a quart too low or high will negatively affect the performance and life of the transmission.

The idle butterfly set screw should be set if you have a mechanical throttle body. The IAC when the engine is warm should have low step counts (below 100) if the steps are too high or too low then open or close the throttle stop as needed. The set screw is a T15 Torx. Idle tuning is a fine mixture of mechanical setup and PCM programming.

To fill and bleed the power steering, jack the vehicle up off the ground and turn the wheel lock to lock 20-50 times while checking the fluid level. Do this with the vehicle off and then with it running.

Be sure to check the engine oil level several times and do not overfill or underfill. Check for vacuum leaks on every single line. To check for vacuum leaks either spray brake cleaner on the suspect location or water. Brake cleaner will make the idle raise temporarily if there is a leak, water will lower the idle. Check for coolant leaks from every single line. Check for power steering leaking. Check for ATF leaking and level after driving. A unused piece of 3/8” hose is a great makeshift stethoscope to listen around to individual engine parts and accessories for grinding or air leaking.


GLOSSARY
ALT: ALTERNATOR, THE DEVICE WHICH GENERATES ELECTRICITY
AFR: AIR FUEL RATIO, HOW MUCH FUEL THE ENGINE IS BURNING IN A GIVEN CONDITION
BOOST: HOW MUCH PRESSURE ABOVE NORMAL ATMOSTPHERIC PRESSURE (~14.5 PSI) IS BEING PRESENTED TO THE INTAKE
CAM SENSOR: THE DEVICE WHICH TELLS THE ENGINE WHERE THE CAM IS LOCATED
CRANK SESNOR: THE DEVICE WHICH TELLS THE ENGINE WHERE THE CRANK IS LOCATED
CONTROL: ANY KIND OF OUTPUT FROM THE COMPUTER OR SYSTEM
ECT: ENGINE COOLANT TEMP
FLEXPLATE: AN ENGINE FLYWHEEL, SPECIFICALLY FOR AN AUTOMATIC
IAC: A DEVICE WHICH HELPS ADJUST IDLE BY ADDING OR REMOVING AIRFLOW
BYPASSING THE THROTTLE INPUT
IAT: TEMPERATE OF THE AIR ENTERING THE ENGINE
KR / KNOCK: THE SENSORS WHICH DETECT IF KNOCKING / PREIGNITION IS OCCURRING BY MONITORING ENGINE NOISE
MAF: MASS AIR FLOR METER
MAP: MANIFOLD ABSOLUTE PRESSURE SENSOR
NA: NATURALLY ASPIRATED MOTOR, NO POWER ADDER SUCH AS TURBO OR SUPERCHARER
O2S: THE OXYGEN SENSOR WHICH MEASURES HOW MUCH FUEL IS BURNED
SENSOR: ANY KIND OF INPUT DEVICE TO THE COMPUTER
SPARK TIMING: WHEN THE SPARK IGNITES RELATIVE TO ENGINE POSITITON
TPS: THROTTLE POSITION SENSOR
TRANS: TRANSMISSION
TFT: TRANSMISSION FLUID TEMPERATURE
TCC: TORQUE CONVERTER CLUTCH LOCKUP
VSS: VEHICLE SPEED SENSOR
WIDEBAND O2: AN OXYGEN SENSOR CAPABLE OF READING RICHER FUEL MIXTURES THAN NORMAL O2 SENSORS
WOT: WIDE OPEN THROTTLE, USUALLY 80% THROTTLE OR MORE

 

[MJEngineering]

Place holder.

 

[imi4tth3w]

wow mike you've been busy!! this build is insane. i'd say your truck definitely deserves one of these

 

[carcrz]

very informative thread. sub