3.8 Supercharged Swap for 94-96 GP (from L67Swap.com)

Michael_Gavan · Posted: Jan Sun 30, 2005 12:47 am

Things you should buy:

1 Walbro High pressure fuel pump #255
2 L67 engine
3 4T65E ? HD transmission
4 Large pry bar
5 36mm axle nut socket
6 L67 High pressure power steering lines
7 L67 tranny lines
8 L67 engine bay fuse box
9 L67 cruise control module and cable (if you want cruise control)
10 Zip ties are essential
11 HD tranny axles for re-fabrication
12 Impact wrench was absolutely necessary for my wheel hub bolts
13 Penetrating oil for hard-to-break nuts
14 Engine hoist
15 Jack stands
16 Metric set of socket and wrenches (I used mostly 7,10,13,15,19 mm sizes)
17 DHP reprogrammed PCM (recommended)
18 Interior harness from an L67 (or if you find someone willing to cut one up ? I have the specific plugs you need from the harness ? just e-mail me)
19 Engine harness from L67
20 Engine harness from your car year
21 New coolant recovery tank
22 Highly Recommended: Engine Scan Tool for getting codes and engine data

Fuel pump installation:

1 First raise and support the back end of your vehicle
2 Then go underneath and find end of the fuel tank closest to the engine bay. There are two straps that run under the tank to hold it up. You want to remove just one side of each strap (the side closest to the front of the car ? they are much easier to get at) and then swing the straps out of the way. I had to remove the exhaust heat shield by the tank to get at the bolts holding the straps on.
3 Once straps are removed, disconnect the fuel feed and return lines and the line that runs to the evap. canister purge valve from the front of the tank.
4 Then swing the straps completely out of the way w/ as little bending as possible and lower the tank.
5 Only the side that you removed the straps from will lower b/c there are still connections running into the back of the tank that you need to disconnect including the fuel pump electrical connection. Remove those and completely lower the tank.
6 Clean off the top of the tank as best as you can b/c there will be dust and dirt on top of it that you don?t want falling into the tank when you remove the pump.
7 There is a lock ring on top of the pump assembly that requires a ?special tool? ? my special tool consisted of two screwdrivers. Put one screwdriver on one clip and push counterclockwise ? while using the other to push from a different clip (this keeps the clip moving in a circular motion and not in a linear one as would occur if you used only one screwdriver).
8 Once removed lift up on pump assembly (you will have to tilt the assembly to get it out).
9 Now remove the pump and filter and install your new Walbro pump (which comes with some directions on pump removal and installation).
10 The way I reinstalled the tank and straps was with the help of a friend. One person hold the tank in place while the other positions a strap and uses a jack to push the tank upwards far enough for the strap to meet it mount holes. I placed the jack across the strap as close to the end of it as I could to help the strap get snug against the tank.
11 Then install the bolt.
12 Repeat process for the other strap.
13 Reconnect all the lines you disconnected ? the ones in the back are a PITA to get back on b/c they are so inflexible. You may want to try and put them back on before you mount the tank ? I found that approach to infeasible, so I managed doing it after I mounted the tank.

Pre-swap Recommended Checklist:

There are a couple of things you can do before the swap that will make it a lot quicker and easier to do.

1 Number one ? Acquire all of the things I have listed above before doing the swap.
2 Get the wiring done (I sent mine to Brian Teel).
3 I did my fuel pump pre-swap, but you don?t have to.
4 Install serpentine and supercharger belt

Removal:

1 Put the front of the car up on jack stands and remove the wheels (make sure your parking brake is on).
2 Next ? remove the calipers (two large star keyed bolts) I tied them to the strut springs so they wouldn?t get damaged
3 Remove axle nuts using a 36mm socket and a lot of leverage ? penetrating oil and blowtorch help. I used the torch to heat up the nuts and it helped a little.
4 Pull off rotors to reveal wheel hubs.
5 The wheel hubs have four 15mm bolts tightened to some ungodly ft/lb. This is where my problem came into play. I couldn?t make them budge at all ? so I borrowed an electric impact wrench from a friend, and used that. Next problem was getting the massive wrench in there to use it ? a universal joint caused the wrench to lose a lot of power and wouldn?t turn the bolts. I ended up removing the control arm (two large bolts and screws attached to the cradle) and swinging it out of the way to get the wrench in there. I still had to use a universal joint on the upper two bolts, but at a very slight angle.
6 Once these are removed you can pry the axles out. This helps to have two people. I wedged a crowbar between the axle and the tranny while a friend tapped on the metal portion before the boot and it slid out eventually (as Ed Morad Suggested). With these out ? you can either take them out of the wheel hub, or not - one of mine was stuck on (so I left it) and the other slid right out ? not a big deal either way.
7 Now you want to move on to the engine bay
8 Remove the hood (two bolts on each side ? plus the hydraulic lift assists)
9 Take off the air box
10 Remove strut tower braces, and upper engine mounts
11 Remove wiper fluid tank, and battery
12 Drain coolant, and remove coolant recovery reservoir
13 Detach upper and lower radiator hoses
14 Detach any and all vacuum hoses
15 Detach throttle and cruise control
16 Detach heater core lines from the back of the engine
17 Disconnect C100 (firewall electrical plug).
18 Disconnect PCM and passenger side fuse box.
19 Remove alternator, coil packs, and map sensor to allow access to the vacuum lines behind the engine.
20 Disconnect those vacuum lines.
21 Disconnect the down pipe.
22 Go underneath the engine and disconnect the lower engine and tranny mounts (2 bolts on each side).
23 Remove brake master cylinder.
24 Remove both cooling fans (I did not remove my radiator ? however it is recommended by most)
25 Now you?re ready to hook up the hoist and pull that baby out!
26 Have a few people around that to make sure nothing clips anything and pull it out!

In between:

1 Have your axles made ? or make them yourself. (For the money I thought it was worth it for someone else to do it) ? What you need to do is use the old axles up until the boot that mates w/ the transmission. Take the metal parts that mate w/ the 4T65E tranny and remove them from the new axles ? you are going to want to put those on the end of your old axles ? that way you have axles that mate to your old wheels and your new transmission.
2 Install new power steering lines ? THESE NEW LINES WILL NOT FIT RIGHT! ? You need to use a pipe bender to make the fit better. They won?t fit exactly as the previous ones did, so make them work as best as you can. Mine are bent above the down pipe because there was more room above then below. I didn?t want them contacting the pipe and making noise. You can also replace some of the hard metal line with flexible rubber fuel line (1/4 I believe). You should only do this on the return line (the one the has a rubber hose attached to the P.S. reservoir). The return line doesn?t carry as much pressure as the feed line ? so you can cut it and use rubber.
3 Its best to have your new harness plugged in to the engine before you install it.

Install:

1 Drop the new engine in ? lower the tranny side first, and mate the studs to their holes, then lower the other side and mate them accordingly.
2 Reattach all your vacuum lines and hook up your battery
3 Install your master cylinder, and brake lines
4 Attach power to your L67 fuse box
5 Hook up harness to the C100 (firewall plug), fuse box, and PCM
6 Connect radiator and heater core lines.
7 Attach fuel lines.
8 Install cooling fans.
9 Attach new tranny lines.
10 Fill up all fluids, and turn her over.
11 You will have to bleed the power steering lines, and the brake lines before driving.

Troubleshooting Tips:

- If it doesn?t crank when you turn your key you will need to bypass the security relay under the dash. I attempted this, but could not make it work ? so I ran a line directly from the yellow ignition wire (running from the steering column) to the starter solenoid, and it works just fine.
- I had to use some starter fluid (ethanol) to start her for the first time. Once I did this ? she started up, but was revving up and down, and not running well at all. This I solved by putting a jumper wire between any pink wire in the fuse box, and the large gray wire. This replaces the fuel pump resistor that 97+ cars have. It tells the pump to come on all the time, and keeps the fuel flowing.
- After fixing that, I had a problem with a high idle. It idled at 3,000 RPM?s. It was because I had the plug for the coolant temperature sensor and the TPS mixed up. I thought it was a bad TPS, so I replaced that. When that did not fix it ? I noticed the backwards plugs. After I switched them around and replaced the TPS it still had no effect. Eventually I figured out the TPS was installed backwards. I inserted it and turned right, while you?re suppose to insert and turn left. This solved the problem, and she idled just fine.
- On my first drive the tranny was slipping pretty badly. I added some more fluid, and it shifted fine.
- Also the first time out I heard a really loud squealing noise that got worse when I revved the engine. I thought it was a belt or perhaps a bad supercharger bearing. I replaced my S/C oil, and drove around for a while. The noise went away, so all is well.
- I got a couple of codes when I first started her up. If you do, just clear them, and see if they come back. If they do ? then worry about them.
- I had some fitment problems with my power steering lines, and I was leaking fluid to the point of making noise, and eventually losing power steering. I had to extend the rubber hose from the reservoir to the metal return line. It attaches right where the line gets all curvy for heat dissipation. I was considering replacing all of that heat dissipation curves with rubber line if I couldn?t get it to fit around the tranny pan. I, however, did get the metal line to fit decently enough, so I didn?t replace it with rubber line. You can if you need to.
- I had problems fabricating a heater core inlet hose; b/c the firewall size is different from the engine size. I tried forcing hose into hose, and it broke apart and sprayed coolant all over my engine bay. So I had to go get a coupler for different size hoses from NAPA auto parts. This fixed my coolant problems.
- This is all I can think of for the moment, but if you come across any problems during your swap or have any questions regarding the process ? feel free to contact me via e-mail and I will be glad to assist you

Written by Jason J Mccool. (Mccool95)