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Ok guys, I've been thinking more about my project and what to do with it. I'm really leaning towards a Z6 swap, upgrading to OBD-I with VTEC :twisted: And I'm considering a future turbo on it.

The first order of business is getting the engine and doing the swap. What is involved with getting this engine to run (correctly) in my 88 Si with OBD-I? I know I'll need a P-28 ECU, but that's all I really know. Would I need the civic gauge cluster? What else is required?

Then later, the turbo. This is the sort of thing I'm not comfortable with doing it myself. How much would it cost and what needs to be done to build a Z6 to safely run a turbo setup? (Hint hint...for example if I were to drop it off at Icon and have it done?)

Thanks guys for reading.

45 Posts
Well, You don't have to upgrade your cluster or VSS (Vehicle Speed Senor) unless you want to but it's unrelated to the swap.

You're already MPFI (Multi-Point Fuel Injected) so that helps alot.

--Make OR Purchase an OBD0->OBD1 Jumper Harness
OR you can splice it into your existing dash harness. The Jumper Harness makes for quick removal should you move the ECU into another OBD0 car (long ways down the road hopefully ;) )
--Part of the conversion is running wires from the ECU to the VTEC Oil Pressure Switch and VTEC Solenoid (easy)
--Another part of the conversion is the distributor wiring. You can either reuse your OBD0 Plugs on the OBD1 Distributor OR you can transfer the OBD1 plugs (engine harness side) onto your existing engine harness. I personally de-pinned the old connectors (OBD0) and put on the OBD1 one.
Picture of my first personally made OBD0->OBD1 Conversion Jumper Harness with the P08 (JDM D15B ECU - BTW, this ECU uses your original 1-Wire O2 Sensor)

--If you use the P28 you'll need to convert to a 4-wire *(Heated) O2 Sensor. This is fairly easy as well providing you can solder.

--You'll want to use the Intake Manifold that comes with your new motor. You only need to transfer your Fuel Injectors. Your Fuel Rail (OBD0) will NOT fit onto the OBD1 Manifold. You can opt to keep your current Peak & Hold Injectors or use the OBD1 Saturated Injectors (Need to remove Resistor Box for this) If you're going turbo you'll want to keep the Peak & Hold's.
--Motor Mounts: The only mount you'll change is the Driverside Mount. Transfer the mount on your old motor onto the new one. The 92-95 mount won't line up. Picture of me trying to use 88-91 Body Mount on 92-95 Engine Side Mount.... Hard to see but the studs don't line up.

--If your old motor has an Oil Cooler located where the oil filter screws on, transfer that to the new motor. Helps a little.

--Air Conditioning - If you have and want to keep it then re-use your old A/C Bracket. The 92-95 is heavier by a couple pounds and the mounting points are different. In the pic, left to right are 92-95 & 88-91

Still thinking.... :)

82 Posts
^^^^^^^ = looks like good info. (dont have time to read it now, though)

The swap itself is pretty straightforward. Ive got a Z6 in my 90 HF and love it.

As far as the wiring goes, here's how I did it:

Step 1 - BUY THIS

Step 2 - Follow the directions that came with it:

JK OBD0 - OBD1 Conversion harness: REV C

Please be careful with this harness. There are 10 wires that need to be connected for proper usage. If there are certain sensors that your engine/ecu does not require, just tape off that numbered wire and leave it unhooked. You will need to have a STOCK wiring harness where it plugs into the ecu. No vtec wires, No O2 wires...STOCK. You will connect all these wires later. So after you have a stock harness, plug this one into the stock ECU harness plugs and Lets go:

Parts Lists:

OBD0 - OBD1 conversion harness
OBD1 injectors (Optional)
OBD1 Distributor
OBD1 Ecu
OBD1 injector clips (Optional)
Extra Wire
Soldering Supplies (If not, cut and splice and use electrical tape)

1. Connect the BROWN wire to one of the black wires on the 4-wire O2 sensor.
(02 Heater Control)

2. Connect the PURPLE wire to the green wire on the 4-wire O2 sensor.
(O2 Ground)

3. Connect the YELLOW wire to one of the black wires on the 4-wire O2 sensor.
(O2 12V Switch)

4. Connect the GREY wire to the white wire on the 4-wire O2 sensor.
(02 Signal)

(Because of the number of different O2 wire colors, these may vary, and you may need to try moving these some. These pin outs should match the OBD1 civic and OBD1 Integra O2 sensors.)

5. Connect the BLACK wire to the Vtec solenoid. This solenoid is a
little canister in front of the distributor. It is a gray, 1 wire square shaped plug.

6. Connect the GREEN wire to the Vtec Pressure switch. It is located below the Vtec solenoid. Connect the GREEN wire on the conversion harness to the BLUE wire on the pressure switch. The other wire needs to be connected to a good ground source. This plug is green and round with two pins.

7. Connect the WHITE wire to the one wire knock sensor located on the back of the block. It is a one-pin plug above the oil filter.

8. Connect the BLUE wire to one side of a toggle switch. Refer to Step 9 to complete the check engine light SCS connector.

9. Connect the ORANGE wire to other side of the toggle switch from Step 8. Wire this up so that you have access to check your engine codes. The OBD0 has a LED on the ecu and the OBD1 you must jumper the check engine light to flash the codes. Hooking this up with allow you to check the codes through the check engine light with the ease of flipping a toggle switch. *If you do not use a toggle switch, these two wires need to be covered to keep from grounding out. *

10. If using the GSR manifold and ecu, you may choose to use the IAB secondaries. If so, you will need to connect the RED wire to the IAB Pink/Blue wire off of the GSR manifold. The Black/Yel from the IABs wire needs to go to a 12V power source.

(Optional if using the OBD1 injector clips and OBD1 injectors)
If you decide to run OBD1/2 injectors, the only thing left that you need to do is take the injector resistor box located on the driver shock tower, rectangular and silver with a green plug. Cut the plug off the resistor box. Discard of the resistor box at this time. Take the 5 wires that are left from the resistor box and solder them together. Use some electrical tape to shield. This is it.

Double check all connectors and start it up. You will need to re-pin the OBD1 distributor to match the (88-91) OBD0 plug as well. This step is fairly easy. Just match all the colors up. There should be 2 white wires that are on the OBD0 distributor plug and only one on the OBD1/2 plug and an extra yellow/green. The larger of the two white wires on the OBD0 side needs to go to the yellow/green wire on the Obd1 side. Therefore, the smaller white wire on the OBD0 side needs to go to the white wire on the OBD1 side. Basically you want to have 2 of the like plugs, either male and female OBD0 or OBD1. You can also cut and solder on the new plugs. REV. C
Step 3 - ENJOY!

OH, also a pointer on dropping the engine in. Its a LOT easier to get her where she needs to be if you take of the tranny side mount. After you drop the engine in, lower it down a bit and bolt it back on. That sucker can really get in the way sometimes.

I'll post some more info when I get a chance.

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