My 4GSwap Notes

These notes are based on 2 different swaps I did personally as well as information acquired from several others in the community.  The swaps that I did personally were an AWD 7 bolt, first with a 5 speed, then with an auto swap in a 92 3000GT VR4.  The next was a FWD 6 bolt with a 5 speed in a 95 3000GT Spyder.

Engine/Transmission Mounts

  • Contact Eric Englert for his custom made 4GSwap mounts for the driver side and rear mount.  He generally does group buys in this group ->   4G63 Swapped 3000GT/Stealth Owners Facebook group Rear 4GSwap mount mounts up to bracket from the AWD Manual DSM stamped "195", part number is MD136195.
  • On the transmission, you want a FWD manual bracket that bolts to the transmission itself, part number is MD738081 for the 5 speed. For the Automatic, you need the two piece bracket from a FWD auto 3000GT/Stealth.
  • Any 3S transmission mount from any year/mode will work.  Since the other two mounts are solid mounts, it is usually best to run a solid mount for that as well, I got mine from Maximal Performance.
  • Eric's Timing side mount bolts up to the 7 bolt timing side.  You can still use a 6 bolt motor, but you'll need a 7 bolt timing side to use the 4G swap mount.  I did this on my second swap which basically required that I take the 7 bolt mount side that bolts up to the block and grind it with my grinder.  There are tons of write ups on that online as people have been putting 6 bolt engines in 2G DSMs for years, it is the same concept.
  • I personally am not going to be running a front motor mount, Eric did not either.  One would need custom made if you wanted to.
  • If you are FWD, do NOT use a FWD transmission from anything except a 90-91 DSM, or you can use AWD DSM transmission of any year with a welded diff.
  • For the 5 speed, 1G and 2G DSM (Eclipse/Talon/Laser) AWD and FWD transmissions will work with the 3S 5 speed shifter cables.  You will want to get the bracket that the shifter cables go in to on the transmission from a FWD 3S model 5 speed transmission.
  • Rear diff needed for the 5 speed swap is the same one in the 91-93 3000GT VR4.  If your 3S is 94+, you will need a rear diff from a 1G VR4/TT to run the 5 speed transmission. To run automatic, you need the 6 speed rear differential from a 94+ VR4/TT.
  • There are multiple ways to handle the center drive shaft, but the best one is using 3000GT/Stealth back two sections and a 2G DSM front section, you have to remove the u-joint from the DSM shaft so you can get to the u-joint flange bolt. You can also run a 1G DSM full drive shaft, but you will need to drill some new holes in the rear diff plate that the drive shaft bolts on to.  Prior to this knowledge, I had a DSM yoke put on my 3000GT drive shaft by a drive shaft shop, these newer discovered options are much better.
  • Intermediate shaft should come from a 1996 Eclipse GSX if you plan to relocate the alternator. No other year of intermediate shaft will work for relocating the alternator with the Jay Racing kit.  I'd also highly recommend that kit. If you're running auto, you need to make sure your intermediate shaft is from a 96 auto, if it is a 5 speed, get it from a 96 manual.
  • Driver side CV axle required swapping the inner cup from a 3000GT driver side CV axle to the passenger side one, then use the shorter CV axle on the driver side.  From what I can tell, any year/model 3000GT CV axles should be able to be used to do this swap around.
  • Passenger side CV axle from a FWD 91 3000GT fits perfectly on transmission for passenger side. I tested this with a 1G 5 speed and a 2G automatic transmission. 91 is the ONLY year with 25 spline inner and 27 outer. Order from Auto Zone part number 8704N here.
  • 7 bolt 4G63 requires a 7 bolt starter plate no matter your transmission generation, the same goes for 6 bolt needing a 6 bolt starter plate.

Wiring / Electronics

The amount of information below may be intimidating to people with little wiring experience, but just know that it is only as long as it is because I wanted to go in to specific detail on what I did and what you will want to do so that there will be no question on what you need to do for your swap. Most of the wiring information below applies to the 1G 3S as it pertains to going from OBD1 to OBD2 and adding another connector at the ECU for that. I had VERY little wiring experience before I spent a couple of days going through wiring diagrams to figure out all of the information that I am going to break down for you below. It is not hard stuff and I personally had all of my wiring that I am listing below done in under an hour with minimal soldering experience once I gathered all of the information below.

  • 91-92 VR4 will use a green top CAS from a 1G DSM for a direct plug in.
  • 93+ will use the same cam/crank sensors that were used on the 2G DSMs for a direct plug in.
  • For a 93+ 3000GT/Stealth, you can either run the crank and cam sensors for a 2G DSM if you're running at 7 bolt engine, or if you're running a 6 bolt engine, you'll want to either create or buy the adapter harness to run a 1G CAS.  If you're running a 6 bolt in a 93+, I highly recommend reading this link for information on this.
  • Use a coolant temperature sensor from a 3000GT, it will thread right in to the thermostat housing from the 4G63.

My VR4 was a 92 fed spec, so the ECU harness only had 3 connectors that go to the ECU, the 2G ECMLink V3 requires the 4 plug and OBD2 vs my 3 plug with OBD1. I’ll explain what I did to make mine work, but there are some things to know first.

COLOR CODED ECU PINOUT IS IN THIS LINK ON DSMTUNERS. If you're not a member of DSMTuners yet, you need to be. It is the best source of information for all things 4G63, minus this swap ofcourse.

Year/Models with the correct wiring for plug and play application for a 2G ECMLink V3 ECU:

  • 94-97 DOHC Turbo 3000GT/Stealth
  • 94-97 DOHC Non-turbo (Cali spec) 3000GT/Stealth
  • 96-97 DOHC Non-turbo (Fed spec) 3000GT/Stealth You can opt to use a harness from any of those and not have to hack up your harness for anything except wiring in the wideband to the ECU and Dakota Digital tach manipulator for a 3S harness (will be talking about this below.)

Now if you’re like me and have 91-93, you can either swap in one of those ECU harnesses and OBD2 port from those year/models listed above, or you can do a little bit of soldering like I did, which is the easier route in my opinion if you don’t mind soldering. The 3 plugs on the ECU harness are correct except one wire needs moved to the missing 12 pin connector.

Things you will need if you want to go the route that I went on a 91-93 harness.

  • OBD2 port and pigtails from any of the year/models I listed above.
  • 12 pin ECU connector and pig tails from any of the year/models listed above.

1G Specific - Two wires from the 12 pin connector to the OBD2 port:

I cut that 12 pin connector and OBD2 port off of my 95 GSX shell personally, you can probably talk someone in to cutting them off a spare harness in one of the DSM groups for you or just buy a harness, you can usually get one for $150 from Performance Partout or from someone in the classifieds groups if you want to go that route. Otherwise, just see if you can find one in a junk yard. OBD2 ports are universal, but the colors on the wires will vary depending on what vehicle you cut it from if not from a 2G DSM.

  • The pink wire in pin 62 on the 12 pin connector needs to go to pin 7 on the OBD2 port.
  • The yellow wire in pin 56 (directly above 62) on the 12 pin connector will need wired in to pin 1 on the OBD2 port.
  • OBD2 pin 4 and pin 5 are ground (use black wires from old OBD1 port)
  • OBD2 pin 14 goes to ECU pin 86 for Vehicle Speed Sensor, yellow/white wire. Use from OBD1 port.
  • OBD2 pin 16 goes to ECU pin 80, it is backup 12v power. Red/black cable.
  • You can look at wiring diagrams to determine if you want to do anything more for your OBD2 port, this was all I needed though.

OBD2 port pins:

Top row (wider side of connector): [1] [2] [3] [4] [5] [6] [7] [8] Bottom row (narrower side of connector): [9] [10] [11] [12] [13] [14] [15] [16]

Wideband

  • Choose which o2 wire you want to use, ECU pin 75 is for the front o2, 76 is for the rear o2, both are white wires. I’m not running narrowband o2 sensors since ECMLink can simulate narrowband with wideband, so it didn’t matter for me. Cut your desired wire (75 or 76) and solder to the output signal wire from your Wideband to that wire.

Fuel injector wiring

  • Remove the electrical tape around the stock 3S front and rear injectors, then redo the tape around them but tape up each one individually back rather than taping them up together.
  • On the stock 3S wiring, if looking from the front of the vehicle, the injector wires on the rear bank are 6 – 4 – 2, the injector wires on the front bank are 5 – 3 – 1.
  • Injector wires 6 and 5 are obviously not used and can be either cut off, taped back, or just left hanging. It is up to you. I left mine hanging.
  • On the 4G63, injector order from looking at the front of the car is 4 – 3 – 2 – 1.
  • From the 3S rear bank harness, hook up plug #4 to injector 4 and plug #2 to injector 2, then front bank, hook plug #3 to injector 3, and plug #1 to injector 1.
  • I personally did not have to extend any of this wiring, but others have needed to extend injector wiring for 2 and 1. It may depend on which intake manifold you use.

Coil pack wiring

This is coil pack wiring based on if you’re using a 1G CAS or a 2G Crank and Cam sensor. They’re basically reverse of each other, you can also click the invert CAS option in ECMLink if you’re running that and got it wrong. I recommend making an adapter harness for this rather than splicing both ends, but it is up to you.

If running a 1G CAS

  • Blue and Black wire from coil pack connector on 3S harness to WHITE on coil pack.
  • Blue and Red wire from coil pack connector on 3S harness to BLACK on coil pack.
  • Black and White wire from coil pack connector on 3S harness to RED on coil pack.

If running a 2G Crank and Cam sensor

  • Blue and Black wire from coil pack connector on 3S harness to BLACK on coil pack.
  • Blue and Red wire from coil pack connector on 3S harness to WHITE on coil pack.
  • Black and White wire from coil pack connector on 3S harness to RED on coil pack.

Alternator wiring

  • Use an alternator from a 1G DSM, connector on it is the same as the stock 3000GT alternator.
  • If you use the Jay Racing alternator relocation kit like I did, you will want to open your main harness that has the alternator wiring in it, pull those 4 wires out for the alternator, then reroute them to behind the engine along the firewall or rear subframe. I personally extended my alternator connector wiring and routed it a weird way which I wouldn’t recommend, just reroute it behind the engine and tape the wires up, it is much better than how I did mine.
  • If you are not relocating the alternator and are keeping it on the front of the motor for the stock 4G63 location, the wiring should just plug in.

Speed Density

  • I’m running an AEM 5 bar MAP sensor and a GM IAT sensor personally. I purchased the Speed Density cable from ECMLink’s website and cut off the MAP sensor end and soldered on the pigtails for my AEM 5 bar MAP sensor, you can use a GM MAP sensor if you want to avoid doing the wiring on that, then it is just plug and play with their cable.

Air Conditioning

One big one that no one has documented yet is how to keep your Air Conditioning! AC is one of those creature comforts that is often deleted in cars that are just meant to go fast because it is heavy and inconvenient to work around sometimes. For those of you who want to do this swap and maybe even daily drive it, AC is a MUST in the summer in my opinion.

On to the important details. You can do this on either a 6 bolt or a 7 bolt 4G63 engine. Here is what you’re going to need:

  • All of your stock 3000GT AC stuff (compressor, evaporator, receiver, condenser, etc.)
  • 2G DSM (95-99 Eclipse/Talon 4G63 models) AC Compressor, bracket, and tensioner. It is VERY IMPORTANT that you get these parts from a 2G DSM that has a 4G63! 420a parts DO NOT FIT THE 4G63.
  • Two AC air compression fitting kits Figuring out the right combination of things that works was the painful part since I had to buy several AC compressors and several sets of AC lines from different cars to figure out what combination worked. My initial thoughts about what AC lines might work were wrong, none from any car I’ve found is a bolt up and go solution. Both AC lines will need to be modified to fit. I recommend the Doorman AC line splice kits. I didn’t measure what worked or where I made my cuts to tell anyone the exact measurements, but you can fairly easily figure it out with it in the car.

For the wiring, I will make this as simple as I possibly can. On the 2G DSM compressor, there is a triangle connector that has 3 black wires. Two are for the sensor on the compressor, 1 is for the clutch.

The 3000GT/Stealth AC compressor on the other hand has all of that and one more sensor that just has 2 white wires. I’m told that is an RPM sensor to shut off the compressor in the event of the belt breaking or something like that. That is some sophistication that the 2G DSM just didn’t have.

So what I did initially is not how I would do it again, and the only reason I say that is because it would have been easy to make an adapter harness instead of cutting the end off at the compressor and putting the other end on. But that is what I did for my initial test and here is how:

Method One:

  • On your 2G DSM AC compressor, cut the triangle connector off.
  • Look at your 3000GT/Stealth compressor connector, remember which wire went to the AC Clutch (maybe label it to save yourself the headache.) Once you know which is which, cut the connector off and get ready to put the connector from the 3000GT/Stealth compressor on.
  • When putting the 3000GT/Stealth connector on the 2G DSM AC Compressor, make sure you connect the AC clutch wire to the AC clutch wire on the DSM AC Compressor.
  • The two black wires from the sensor on the 2G DSM AC Compressor will connect to the two other black wires on the 3000GT/Stealth AC Compressor connector. It does not matter which is which.
  • The two white wires are for an RPM sensor which the 2G DSM compressor does not have, when you cut those, they’ll need soldered/connected together. The sensor would typically shut off the compressor if it is running and isn’t spinning to prevent damaging it, that is in the event of a belt breaking. That is just some sophistication that the 3000GT/Stealth had that a 2G DSM did not.
  • Done! Now you’re ready to put it on the car and plug it in. The big down side to “method one” above is that you need to do that again if you ever have to replace the AC compressor for any reason. That is why I decided to have a method two, which is a simple adapter harness that you can make on your bench easily if you have the spare connectors. On that note, I highly recommend buying some hacked up wiring harness to keep around. They’re infinitely useful for making adapter harnesses.

Method Two:

Making an adapter harness, you’ll need the following:

  • A female triangle connector with pigtail that plugs into the 2G DSM AC compressor. If you can get one from a 2G DSM wiring harness, that is great! Otherwise, this connector exists in several places and you can hack it off a spare 3S harness.
  • A male rectangle connector with pigtail that plugs in to 3S harness for the 3S AC compressor. I just cut this off the 3S AC compressor personally.
  • 2 foot of 16GA wire. I like to give myself some play room when making things like an adapter harness, and since I have a spare harness to hack off of, I have plenty of wire. Once you have the two connector you need, you just need to match up your wires. Best thing to do here is to plug in your triangle female plug with its pigtail right into your 2G DSM AC compressor so you’ll have a pretty straight line view of which wire is which. I cut the rectangle connector off the 3S AC compressor after labeling which wires were which, now you essentially want to wire them together to where they’ll be wire to wire all the same. On the 3000GT/Stealth AC compressor connection side, we won’t have where for those two white wires to go, so we want to write those two together inside of our adapter harness.

I highly recommend making an adapter harness over method one if you have the connectors or can source them. It will save you from having to redo all of the wiring changes if you ever have to replace your AC compressor.

I’m going to build several of these adapter harnesses and sell them for $50 shipped if anyone is interested.

Method Three:

The slice and splice method. Basically following all of the same information as method 2, except you just cut the rectangle male connector off of your 3S harness and put the 2G DSM triangle connector in its place while looping the two connections that go to the white wires on the 3S compressor connector. I’m not a big fan of cutting a good wiring harness up, so this isn’t my preferred method, but it will do the trick.

There it is folks! Now you can do your 4G swap and keep your AC without having to buy a bunch of unnecessary parts or do a bunch of research to figure it all out.

Exhaust

  • 2G GSX downpipe fits perfectly on the 7 bolt motor to the downpipe exhaust hanger.
  • Suspect any 3000GT exhaust should bolt up to the downpipe due to where it sits, but have not tested.

Intercooler setup

  • I personally had a bunch of left over FMIC piping that I had in my garage from some kits I bought cheap for my Eclipse and a core that I bought specifically for my VR4.  It was easy to route everything for me.  I'd assume that most normal 2G DSM FMIC kits would fit with my setup except the VRSF kit because it is a "short route" kit.
  • I wasn't able to use a 1G DSM FMIC because the pipes that came out wouldn't clear the AC condenser.  If you delete AC and use a 1G DSM radiator, you should be able to use a 1G DSM FMIC.

Miscellaneous

  • I used the thermostat housing, water pipe, and radiator hoses from a 2G Eclipse GSX/GST. Any 3S radiator will work with this setup.
  • To run a 2G power steering pump, you can unbolt the line from the subframe and carefully bend the power steering line that went to the 3S power steering pump out to make it go to the 2G DSM power steering pump.  The other line that goes to the power steering reservoir wasn't long enough, but it is just a hose you can get from any parts store.  Buy 2FT, cut it down to where you desire it to be.

In addition to these notes, please also check out the documentation provided by Eric Englert in the 4G63 Swapped 3000GT/Stealth Owners Facebook group here.