by Skidtron89
ODB0 to ODBI conversion for a 88-91 CRX Si.
I know it sounds like a long division problem that you wouldn’t want to do on paper, but it’s actually the title for a full set of instructions to put a D16Z6 OBD 1 conversion in your 88-91’ Honda Civic/CRX Si. Many people want to use piggyback computers and non-CARB approved parts, but why run your car illegally when you could get it done right the first time and be legal in the process? This swap will include the D16Z6 motor swap as well as all of its associated support equipment such as the P28 ECU and the full engine and ECU wiring harnesses.
There is no other emissions related device to worry about, as there is no EGR for either the D16A6 or the D16Z6 just a charcoal canister neither of which is electronically monitored by the ECU for the evaporative emissions like an OBD 2 system has. You will notice also that there are many parts being changed on the new motor. This is not necessary but if you do put new parts on the engine it won’t need to be serviced for a while, and you will have the peace of mind that comes with having a bunch of new parts on it. This is intended to be a guide not a perfect step by step although I have tried to make it as accurate as possible.
I have included a price vs. parts list as well. Hopefully there are very little mistakes and your swap goes well. It will be your responsibility to get your car / engine certified by the state of California when you are done with the swap. You can do so by going to you’re nearest state emissions referee. The California state referee scheduling center telephone number is 1-800-622-7733. I believe they can also tell you where the nearest referee is and how to get there. For further information concerning smog in the state of California you can check out the California Air Resources Board website at:
http://www.arb.ca.gov/
If you do everything right you could have one of these if you live in the great state of California. I have been pulled over twice now with the emissions certification and been “searched” both times they haven’t asked any further questions after showing them the label and the CARB paper work for the Greddy turbo kit. One officer just said “That’s a nice setup you’ve got there. I’ve seen enough have a nice night.” I would have been sent to the referee both times for inspection if I didn’t have the label already not to mention the court time and costs.
And you engine bay should look like this when complete minus the turbo stuff of course.
Price vs. Parts
These were my approximate costs for the swap. Your costs will vary but this will give you a good idea of what you’re looking at. Also remember a lot of my cost was due to new replacement parts which theoretically you do not have to buy. And before anyone says I could have swapped a B-series motor in for the same you are most definitely wrong as I didn’t have to:
1. Buy special mounts that only left me with three mounts instead of four hence mounting the motor incorrectly and not as Honda designed it. Also allowing it to move more freely as there is no front torque mount.
2. I did not have to cut anything to make the motor fit
3. I did not have to bend anything or hit things with hammers
4. Nor did I have to swap my axles
5. I could have easily used my stock air conditioning setup with out buying a special mount
6. My shift linkage is the same as stock so no cost there
7. Another point is that a B-series motor wouldn’t cost $500.00
8. Nor would the replacement parts or the aftermarket tuning parts be as cheap as they are for a D16Z6
9. Plus the D16Z6 weighs less. Not a ton but enough to matter
Just remember there are a lot of hidden cost in a motor swap so make sure you have some extra money in case you break something and you need the new part to make your car run. I have tried to give you an idea of the cost but remember your engine might come with parts missing or broken so be careful with where you buy it. I am not saying a B-series engine wouldn’t be good in this car I am saying it can’t be done for as little money as this swap. Unless pretty much all of the parts are free
| Motor swap | Cost |
| D16Z6 motor (Complete) | $ 500.00 |
| Exhaust manifold and down pipe | $ 75.00 |
| D16Z6 car wiring harness | $ 75.00 |
| Clutch set 89-91 Si | $ 189.00 |
| Rear main seal | $ 8.00 |
| Timing belt | $ 45.00 |
| Water pump | $ 40.00 |
| Auto tensioner | $ 45.00 |
| Crankshaft seal | $ 6.00 |
| Camshaft seal | $ 6.00 |
| Spark plugs | $ 20.00 |
| Pilot bearing | $ 2.00 |
| Flywheel resurfacing | $ 50.00 |
| O2 Sensor | $ 70.00 |
| P28 ECU | $ 150.00 |
| Electrical connectors and misc. | $ 40.00 |
| S20 Transmission back up switch | $ 12.00 |
| Total cost | $1,343.00 |
Proper wiring harness appropriation
The picture below shows you how the D16Z6 engine wiring harness and ECU wiring harness need to be removed from the donor car to make your life easier.
Here are some pictures of how the interior wiring harness or the “car” wiring harness should be cut to leave you with the part you need to follow my swap instructions. In the first picture you can see I have an entire 92-95 Si/EX wiring harness. The red shows where to cut the harness and the blue circle show key parts of the harness you will need. In this first picture every thing to the right of the right most cut resides under the dash and most of it is all on the driver’s side of the car or the center console. All of it is garbage as far as this swap is concerned.
See the top blue circle? Those are the ECU / Engine connectors they reside in the engine bay on the left side by the strut tower there are three you need. See the bottom blue circle? That contains both the ECU connectors and the Data link connectors. See the other pictures for close ups. The top red cut a connector going to parts of the engine bay that are not needed for this swap cut it off. See the fuse box? Cut it off! And see the last red cut mark I haven’t said anything about yet? Cut that off too! Hah!!!
Now in this picture you can see the ECU connectors and the ECU / Engine connectors a bit better. See the grommet in the middle of the wiring harness? That is where the wiring passes through the passenger side of the firewall when the harness is still in the car. Now draw a line in you mind from the ECU connectors to the ECU / Engine connectors. That is the part you want with a bit of the wiring going towards the upper cut so you can splice a few of the wires to the car’s existing wiring harness.
The easiest thing to do when the harness is still in the donor car is to cut off the wiring going to the fuse box and the wiring that goes to the left if you are viewing the portion of the wiring harness that is inside the car from the passenger seat. Next you would cut off the wiring that leads to the connector that is at the bottom of the picture you would see it leading towards the headlights on the passenger side of the car.
Now in this picture you can see the ECU connectors and the ECU / Engine connectors a bit better. See the grommet in the middle of the wiring harness? That is where the wiring passes through the passenger side of the firewall when the harness is still in the car. Now draw a line in you mind from the ECU connectors to the ECU / Engine connectors. That is the part you want with a bit of the wiring going towards the upper cut so you can splice a few of the wires to the car’s existing wiring harness. The easiest thing to do when the harness is still in the donor car is to cut off the wiring going to the fuse box and the wiring that goes to the left if you are viewing the portion of the wiring harness that is inside the car from the passenger seat. Next you would cut off the wiring that leads to the connector that is at the bottom of the picture you would see it leading towards the headlights on the passenger side of the car.
This picture gives yet even a closer shot of the ECU connectors and the data link connectors are at the bottom of the shot. The grommet at the lower side of the shot is the one in the chassis leading to the door like the stereo and power window and locks stuff. All of which is not needed and can also be cut loose while the harness is still in the car.
Considerations:
Some things to note before starting are that it will be easier to do the swap if you don’t want your air conditioning anymore and if you get a complete engine with all it’s parts to include the distributor and entire intake manifold with the fuel injection parts that are stock. Also note that you must use the proper injectors and the old ones will not work, as they are another type of injector that is incompatible with the 92-95’ ECU. You will have to jumper the check engine connector from now on to pull codes from the ECU so it is important that you install it and the data link connector or you will not be able to troubleshoot if you run into problems nor will you be able to get your engine certified by a state referee.
Also get a higher pressure radiator cap since the 92-95’ engine runs it’s stock radiator cap at a higher pressure than an 88-91’ Civic. It may be only due to the size of the stock radiator on the 92-95’ in comparison to the 88-91’, which is about half the size, but it will help your engine stay cooler anyways. It is easy to do and will let the engine run much cooler. If you go to AutoZone you can get an Accord / Prelude radiator cap that runs at 16psi instead of 13psi which is what the stock one runs at. They look identical and are usually hanging right next to each other. If you are having trouble finding it just find the stock one and look around next to it till you see the higher pressure one that looks the same. They say what they’re pressure rating is on the top of them.
Also you could go to a colder thermostat like I did. I found a 170-degree thermostat instead of the stock 195-degree thermostat. Since I live where it is often 100 degrees in the summer this helps a lot but if you live in a cold climate then just stick with the stock one. I also run Redline Racing’s water wetter to keep the temperature nice and cool find it at
http://www.redlineoil.com/ . Their oil is probably one of the best on the market today also. Other than that just take time and look over your new engine and make sure it is in good order. Also get any parts you want to replace ahead of time so you don’t have to leave your car on jack stands for a week waiting for parts. It would make life easier if you had the repair manual for both of the engines / cars and a good idea of what you’re doing before you start. Take your time and consult an educated mechanic for anything that you don’t understand.
Quick note: If you have a D16Z6 that is a manual then take the flywheel off of it and take it to the machine shop to have it resurfaced while you are doing the rest of the swap. Chances are that you will need it right about the time the machine shop is done with it. It usually takes 1-2 hours for them to do it. It is cheap insurance against a slipping clutch. The last thing you want to do is get the swap done and have to drop the transmission again to resurface the flywheel. If your D16Z6 was automatic in it’s previous life then you’ll just have to wait till you get the D16A6 flywheel out and then send it to the machine shop but don’t worry it shouldn’t slow you down too much. The 89’+ flywheels are the same and all use the same clutch disc and pressure plate. The 88’ flywheel clamping surface is smaller and the clutch is smaller and weaker. It is highly recommended to use an 89’+ flywheel and clutch. If you have an 88’ transmission then unless you get a newer one you are stuck using the 88’ flywheel and clutch.
D16A6 engine and transmission removal
1. Apply the parking brake
2. Disconnect battery
3. Loosen the front lug nuts
4. Jack up the car
5. Support car with jack stands
6. Remove front wheels
7. Remove the splash shield
8. Remove hood
9. Drain coolant
10. Drain engine oil
11. Drain transmission oil
12. Remove air intake tube from throttle body to air box
13. Remove battery
14. Remove battery tray
15. Disconnect the fuel line from the fuel rail
16. Disconnect the return fuel line from the fuel pressure regulator
17. Disconnect and unbolt the wiring harness that runs to the resistor so that it is free of the chassis
18. Unbolt the ground strap from the valve cover
19. Disconnect the throttle cable
20. Unplug the engine wiring harness connectors from right rear of engine bay
21. Unbolt the engine wiring harness from the chassis by the left strut tower
22. Disconnect the alternator wire from the under hood fuse box
23. Disconnect the brake booster vacuum hose from the intake manifold
24. Disconnect the emissions control vacuum hoses from the intake manifold
25. Disconnect upper and lower radiator hoses from engine
26. Disconnect heater hose from the engine
27. Unbolt radiator mounts
28. Unplug all radiator fan plugs
29. Remove coolant overflow tank
30. Remove radiator with fans still attached
31. Disconnect both pieces of shift linkage from transmission
32. Disconnect clutch cable
33. Remove speedometer drive cable be sure to keep the retention clip (Don’t loose it or the cable won’t stay in and no VTEC for you!)
34. Unbolt exhaust manifold down pipe from the catalytic converter
35. Unbolt the 14mm through bolts at the top of the strut forks
36. Remove the forks from the struts and lower control arms
37. Remove the two 17mm nuts on the lower ball joints
38. Lift the hub out of the lower control arm
39. Unplug the half shafts. Swing them out of the way.
40. Fold all wiring and hoses onto the engine that are attached to it
41. Hook up lifting chains to the engine
42. Lift engine slightly
43. Remove all motor mount bolts
44. Check that the engine is free one last time
45. Lift engine and transmission from engine bay slightly angled down on the passenger side
And that’s how you take it out; it shouldn’t take more than 2 hours with one person with hand tools. Me and my friend Jake took one out it 20 minutes with hand tools before and our average time is 30-40 minutes with smoke breaks and chitchat
Engine Bay Prep:
1. Clean everything that you can’t when the engine is in the car also paint anything that needs it
2. Unplug the wiring harness from the MAP sensor and purge control solenoid
3. Remove the MAP sensor and purge control solenoid assembly from the firewall. You can set this aside as you won’t be using it on the new engine.
4. Unbolt and unplug the resistor from the left rear of the engine bay. You can set this aside as you won’t be using it either on the new engine.
5. Unbolt old catalytic converter and remove it (Only if you have a new one to replace it though)
6. Install new catalytic converter
Now is a good time to re-route any hoses or wires that are hard to get at when the engine is in the car. It is also a good time to take a leak or eat something. Now is a good time to take the air conditioning equipment out of the car if you would like to do so. Although it’s not necessary it will save weight and a lot of space.
Also you won’t have to modify the condenser fan to fit the D16Z6 exhaust manifold to your engine. I took mine out to save weight and get a lot more space in the engine bay. Plus I don’t care anyways about having it. I am building the car to go fast not carry parts that I will only use half of the year.
D16A6 un-preparation:
1. Unbolt valve cover and remove it
2. Unbolt upper timing belt cover and remove it
3. Unbolt harmonic damper and remove it (This is better done with an impact gun)
4. Unbolt lower timing belt cover and remove it
5. Unbolt motor mount from the block like in the picture below
1. Unbolt down pipe and remove it
2. Unbolt exhaust brackets and remove them
3. Unbolt engine brace and remove it
4. Unbolt flywheel access cover and remove it
5. Unbolt water neck from front of head and remove it you’ll need this later so don’t loose it
6. Unplug back up switch and remove it if you have a hydro back up switch from the S20 transmission (92-92 Hydraulic transmission) if not leave it in there
7. Unbolt starter and remove it
8. Unbolt transmission and separate it from engine
9. Now put the engine back together so you can sell it on EBay or whatever
These steps should take you about 30-40 minutes with regular hand tools and an impact gun.
Transmission preparation:
1. Clean exterior of transmission gasoline works best or brake parts cleaner
2. Clean transmission bell housing
3. Undo throw out bearing retention spring
4. Remove old throw out bearing
5. Remove release fork and throw out bearing retention spring
6. Clean release fork and throw out bearing retention spring
7. Clean input shaft of the transmission
8. Grease input shaft
9. Grease tips of release fork
10. Install new throw out bearing, throw out bearing retention spring, and release fork
11. If you have received the S20 transmission with the D16Z6 then remove the back up switch and put it in the L3 transmission as it will be able to plug into the wiring harness correctly. Otherwise you can splice the wires of the L3 back up switch to the wires of the D16Z6 wiring harness you will know which connector it is because it won’t have anywhere to plug into one everything is plugged in. You could also get a S20 back up switch from the junkyard like I did if you don’t have the S20 transmission to steal it from and still want the cleaner install.
This step should take you no more than 30 minutes with hand tools
D16Z6 Engine preparation:
1. Unbolt valve cover and remove it
2. Unbolt upper timing belt cover and remove it
3. Rotate engine to TDC
4. Unbolt harmonic damper and remove it
5. Unbolt lower timing belt cover and remove it
6. Unbolt motor mount from the block and set it aside as you will no longer need it
7. Bolt on the 88-91 motor mount onto the block
8 Loosen the auto tensioner
9. Remove timing belt
10. Remove auto tensioner
11. Remove water pump
12. Remove camshaft gear
13. Remove camshaft seal
14. Remove crankshaft gear
15. Remove crankshaft seal
16. Clean the block where the timing covers usually are
17. Install new camshaft seal
18. Install new crankshaft seal
19. Install new water pump
20. Install camshaft gear
21. Install crankshaft gear
22. Install new auto tensioner
23. Install new timing belt
24. You will have to trim the timing covers to fit the new motor mount.
Remember measure twice cut once!
25. Install lower timing belt cover
26. Install harmonic damper
27. Make sure the engine is timed properly
28. Install upper timing belt cover
29. Install valve cover
30. Remove old spark plugs
31. Install new spark plugs
32. Remove old water neck at front of head. You won’t need this for the swap.
33. Install D16A6 water neck
34. Unbolt and remove distributor cap
35. Unbolt and remove distributor rotor
36. Bolt on new rotor
37. Bolt on new cap
38. If you had a 88’ then you will need a clutch set and flywheel for a 89-91 Si instead of the 88’ as it has a different amount of teeth on the input shaft and the clutch is smaller (Read: weaker) anyways. You need an 89+ flywheel too! The flywheel and clutch sets for 89+ are all the same except when you get a set for a 92’+ hydraulic transmission you won’t have the correct throw out bearing so to make it easy on yourself get a 89-91 Si set. I have a lifetime warranty 91 Si clutch set from AutoZone and have gone through two free clutches this way all I had to do was the labor to swap it.
39. Remove pressure plate and old clutch disc
40. Remove flywheel
41.Get flywheel resurfaced. You didn’t think of this already? You didn’t read the quick note at the beginning of the article? You never did follow directions very well did you? He He! This is optional but make sure it’s in good condition if you are not going to resurface it. Also make sure there is no oil on it if your not sure clean it well with a degreaser. This goes for all the clutch components because if there is oil on them your clutch won’t work.
42. Remove rear main seal
43. Clean block
44. Install new rear main seal
45. Install new pilot bearing into flywheel
46. Install resurfaced flywheel
47. Install new clutch disc and pressure plate
48. Remove old oxygen sensor
49. Install new oxygen sensor
50. Clean the block more!
51. Bolt the transmission to the D16Z6 engine
52. Bolt the D16A6 starter onto the transmission
53. If you didn’t have the S20 transmission back up switch then you need to splice the two wires on the L3 transmission back up switch to the ones on the D16Z6 engine wiring harness. There are in a two-pin connector and it doesn’t matter which one goes to which, but try to be smart and match the colors if possible.
Depending on your skill getting the engine ready to be dropped in could take a while. And remember that it’s easier to time the engine while it’s out of the engine bay so get it right the first time. Remember to turn the motor over by hand a few times to make sure it stays in time as you do not want to kill your new engine as a result of bad timing.
Valves do not like to share the same space as pistons!
Interior of car/ECU preparation:
1. Pull back carpet on passenger side floorboard
2. Unbolt ECU shield and remove it
3. Unbolt and unplug ECU and remove it go ahead and put that baby on EBay too!
That was an easy one!!! !!! This guy’s car was unnecessarily messy I would recommend having a cleaner environment to work in. It will make it easier to work on.
Wiring Concerns
Important note:
Whenever wiring is concerned the pins are counted left to right top to bottom while looking at the wire side of the female connector with the release for the connector at the top. Take a moment and picture that so you do it right as this is the way Honda does it and if everybody does it this way the world would be a better place! The only exceptions are noted on the diagrams that have the exceptions.
All connections that don’t need to come apart for any reason should be soldered and heat shrink to maintain stock reliability as many kinds of connectors come loose after vibrating and being exposed to the elements. Also note that I have used Molex connectors in my installation that is of course optional as they are expensive and in some cases hard to find. I like them because they give a professional look and maintain their connection very well even under adverse conditions.
You can find them at Fry’s Electronics or Radio Shack or whatever electrical parts store is near you. I think Radio Shack calls them molded nylon plugs. Get extra pins in case you mess up and get the pin extractor tool, as you will probably need it. I used the crimp style ones but you could get the solder ones if you like. Oh! Yeah the crimper for them is costly too but I have used mine so much it has paid for itself many times. Or you could use quick disconnect style connectors if you would like but they have a tendency to not make very good connections and I use as little of them in my car as possible. This is a picture of what they look like that I stole from the
http://www.radioshack.com/ site. You will find them classified as power connectors.
0.093” Is the bigger of the two sizes that Molex connectors come in and more appropriate for automotive. There is also a 0.062” size but it is harder to work with and if current is pretty high you would want to stick with the 0.093” size anyways. Or you could just use what ever connectors you usually use.
If you decide to solder the connections or use butt splice connectors then follow the Wiring walk thru at the end of this article instead of the following procedures. The connections are the same but on the
walk thru the wires are done one at a time in steps to help the less electronically inclined folks. It also leaves the burden on you to decide where wiring should be able to be detached for engine wiring harness removal in the future.
Don’t do things like this! Just follow the directions
D16Z6 Wiring harness preparation:
I have described the process as if the wiring harness was lying in the engine bay as it does when the engine is installed so right means your right when you are looking at the engine from the front of the car. I know it is not proper automotive way since that is the left of the car, but I didn’t want people looking on the wrong side of the car. So like I said pretend you are looking at the wiring harness from the front of the car, as it would be installed regularly. It is assumed that the stock D16A6 wiring harness is removed already with the engine as it is not used and should be set aside. Only the wiring harness that is attached to the car should remain. Refer to the below picture if you need to see what the connectors look like:
1. Remove engine wiring harness from D16Z6.
2. Open wiring harness loom from the fuel injectors side to the engine / ECU connectors. This is on the main loom that goes across the engine you can leave the small loom that goes to the sensors alone.
3. Label wires at junction C125 (Which is at the right rear of the engine bay on a 92-95 SI/EX) and also on the side by the main harness. All the wires are yellow with a black stripe so pay attention. C125 looks like a plug that is blocked off you can’t miss it
4. Cut wires close to the C125 connector and close on the main harness then reconnect them so that the connector wiring is now very short
5. The 8th wire on the C125 junction needs to be cut off the 14 pin connector and extended to the engine / ECU connectors You can use the cut wires from the above steps to extend it so you can keep the wire all one color. Remember solder and heat shrink!
6. Cut off the 14 pin connector that is also at the right rear of the engine bay label them if you think you will get confused, but every wire on that connector is a different color than each other so there should be no confusion.
7. Pull all wires from the 14 pin connector to the other end of the harness
8. Cut off the two pin connector with the thick gauged black with a white stripe and the black with a yellow stripe wires at the right rear of the engine bay
9. Pull these wires to the other end of the harness
10. Cut the thick gauged black with a white stripe and the black with a yellow stripe wires to the length of the engine / ECU connectors and put connectors of your choice on them. This is the only place I used quick disconnect connectors in my install since the wires need to be able to be unplugged in case I pull the motor out for maintenance. See the connection below after step 16.
11. After all the wires have been pulled from the right to the left close the harness back up like how it was and recover it with new electrical tape.
12. Tie wrap the C125 junction to the main harness so it won’t move and so when the harness is installed it will be hidden under the intake manifold
13. Cut all wires from the 14 pin connector to the same length to make the connections cleaner
14. Build the Molex #2 side B,15 pin connector as per the pin out below
Engine connector (Molex #2) Pin out side B (Male side)
These are the 14 wires from the connector you cut off on the right side of the engine bay. Remember?
| Molex Pin # | Engine Wire Color | Engine Wire Function |
| 1 | BLK | Ground |
| 2 | YEL/BLK | Junction C125 |
| 3 | BLU/YEL | Electronic air control valve |
| 4 | YEL/RED | Oil pressure switch |
| 5 | RED | Purge control solenoid |
| 6 | BLU | Tachometer signal |
| 7 | BLK/YEL | Alternator |
| 8 | WHT/BLU | Alternator |
| 9 | YEL | Back-up switch |
| 10 | GRN/BLK | Back-up switch |
| 11 | YEL/GRN | Coolant temperature sender signal |
| 12 | GRN | Coolant temperature switch |
| 13 | YEL/BLU | Vehicle speed sensor (N/A but there for future use if needed) |
| 14 | YEL/WHT | Vehicle speed sensor (N/A but there for future use if needed) |
| 15 | N/A | N/A |
15. Cut off the wires from connectors C210, C211, C212 (In the under hood fuse box, closest and parallel to the firewall), and C217 as you need them to build the Molex #2 side A, 15 pin connector. See below for the location of the connectors:
16. Connect the thick-gauged black with a white stripe and the black with a yellow stripe wires from the car’s harness you just cut to the ones you just pulled on the engine wiring harness. If you do not do this the car will not start and the distributor won’t have power! When you are finished with that continue with building the Molex side A connector as per the pin out below.
Engine connector (Molex #2) Pin out side A (Female side)
These are the wires that are cut off the stock wiring of the car to be connected to the wiring you moved on the D16Z6 wiring harness. The two cars have them on opposite sides of the car hence the reason for moving the other wiring to this side. There are only a couple exceptions that didn’t make it worth it to have an extra wiring harness on the right side of the engine bay. Not to mention all the wiring is on one side and away from the drive belts this way. It also makes for less clutter in the engine bay.
| Molex Pin # | Harness Wire Color | Harness Wire Function |
| 1 | BLK | Ground C211 pin#5 |
| 2 | BLK | Junction C125 (Run wire to pin#8 and 10 on Molex #1 side B) |
| 3 | BLK | Electronic air control valve (Run wire to pin #2 on the Molex #1 side B) |
| 4 | YEL/RED | Oil pressure switch C211 pin #6 |
| 5 | BLK | Purge control solenoid (Run wire to pin #5 on the Molex #1 side B) |
| 6 | BLU | Tachometer signal C211 pin #8 |
| 7 | BLK/YEL | Alternator C211 pin #1 |
| 8 | WHT/BLU | Alternator C211 pin #2 |
| 9 | YEL | Back-up switch C217 pin#3 |
| 10 | GRN/BLK | Back-up switch C217 pin#6 |
| 11 | YEL/GRN | Coolant temperature sender signal C211 pin#7 |
| 12 | YEL/GRN | Coolant temperature switch C212 pin #5 |
| 13 | N/A | N/A |
| 14 | N/A | N/A |
| 15 | N/A | N/A |
17. Put the harness back on the motor and make sure it’s secure and installed properly so nothing gets damaged or tangled in a rotating part
18. Pull out the left over plugs and wiring that are no longer connected to anything to make the install cleaner.
Now the Engine bay should be wired and there should be no wiring going to the right side of the engine bay at all. The white plug C313 that is ` in shape left behind on the right rear of the engine bay could be cut off and the wires tucked away for cosmetic reasons at this point if you wish to do so. Also then you could close up the harness on that side. See picture below:
D16Z6 ECU wiring harness preparation:
1. Open up the cut up wiring harness’s loom from the donor car. All of the loom should be removed from the harness at this time so that you can easily access the wires.
2. Remove all wires that do not go to either the ECU connectors or the three main engine wiring harness connectors. You should just be able to pull them and they will slide out from the harness since they are not connected to anything. You shouldn’t have to cut anything at this point.
3. If you are using the Molex connectors then build the Molex #1 side A,15 pin connector as per the pin out below.
ECU connector (Molex #1) Pin out side A (Male side)
These are the wires coming from the new ECU’s wiring harness that need to be spliced into existing wiring that is on the car already. Most of which are cut off of the stock ECU’s wiring harness.
| Molex Pin # | ’95 ECU Pin # | ECU Wire Function |
| 1 | A7/A8 | Fuel pump control signal (GRN/YEL) |
| 2 | A9 | Electronic air control valve signal (GRN/WHT) |
| 3 | A12 | Radiator fan control signal (YEL/GRN) |
| 4 | A13 | Check engine light signal (GRN/ORG) |
| 5 | A20 | Purge control solenoid signal (RED) |
| 6 | A23 | PGM-FI Relay ground ties to A24 (BLK) |
| 7 | A24 | Engine ground ties to A23 (BLK) |
| 8 | A25 | Power to junction C125 tie to B1 (YEL/BLK) |
| 9 | A26 | Engine and data link ground (BLK/RED) |
| 10 | B1 | Power to junction C125 ties to A25 (YEL/BLK) |
| 11 | B9 | Starting input for ECU and PGM-FI relay (BLU/WHT) |
| 12 | B10 | Vehicle speed input signal (YEL/BLU) |
| 13 | D1 | Battery input (Hot at all times) (WHT/BLU) |
| 14 | D7 | Data link connector (TXD and RXD)(LT.BLU) |
| 15 | D10 | Electronic load detector signal (GRN/RED) |
4. Cut the wires off of C451 (Plug A), C452 (Plug B), and C453 (Plug C) connectors from D16A6 ECU harness as you build the Molex #1 side B,15 pin connector. After you are sure that all the proper wires and connections have been made you can cut off the remaining wiring and pull out the stock ECU wiring harness. You will no longer need it after this point. Build the Molex connector for this side B as per the pin out below.
ECU connector (Molex #1) Pin out side B (Female side)
These are the wires that are cut off of the stock ECU wiring harness so that they can connect to the new ECU wiring harness
| Molex Pin # | Harness wire color | Harness connection |
| 1 | GRN/BLK | Wire from C451 Pin #14 and 15 |
| 2 | BLK | Run wire to Molex #2 pin 3 side A |
| 3 | YEL/GRN | Wire to C452 pin #12 |
| 4 | GRN/ORG | Wire from C452 pin#13 |
| 5 | BLK |
Run wire to Molex #2 pin 5 side A |
| 6 | BLK | Wire from C451 pin #9 |
| 7 | BLK | Wire from C451 pin #10 |
| 8 | BLK | Run wire to Molex #2 pin 2 on the side A |
| 9 | Engine and data link ground |
| 10 | BLK | Run wire to Molex #2 pin 2 on the side A |
| 11 | BLU/WHT | Wire from C452 pin #7 |
| 12 | YEL/RED | Wire from C452 pin #18 |
| 13 | WHT/GRN | Wire from C452 pin #1(WHT/BLU) |
| 14 | Data link connector |
| 15 | GRN/RED | Wire from C452 pin #10 |
Also be sure to connect the ignition timing check and data check connectors at this point as you will not pass smog if you do not have them!!! They may be disconnected or partially disconnected due to cutting at this point. These are a two-pin connector and a three-pin connector near the ECU some of the wiring might not be connected anymore so you will have to splice it back in where it belongs on the ECU harness.
It’s not a big deal just follow the following wiring diagram below to verify that the connections are correctly made. The main thing to check is that pin 2 on the three pin connector has the wire running to a power source. I have chosen pin D1 as it is easy to access and in the same area saving you from running a wire somewhere to get 12Vs.
Dropping in the new motor
1. Hook up lifting chains to the engine make sure it is leaning towards the transmission side again
2. Slowly, slowly lower the new engine back into it’s new home once you get it close you can slide the motor mount bolts in and hand tighten them all first. Keep them relatively loose till they are all started so that you can wiggle the motor around a bit.
3. Slide the half shafts back into the transmission
4. Lower the hub’s lower ball joint back into the lower control arm
5. Bolt the 17mm nuts back on to the lower ball joints
6. Put the forks back in between the struts and lower control arms
7. Bolt the forks up again
8. Bolt up the shift linkage
9. Bolt up the down pipe to the catalytic converter
10. If you are using the D16A6 exhaust manifold (Which is more restrictive) then there is no fitment problems, but if you are using the D16Z6 exhaust manifold and retaining your air conditioning then you will need to modify the condenser fan a bit for the O2 sensor to clear it.
11. Put the radiator and fans back in
12. Bolt up the radiator and plug in the fans
13. Put the overflow tank back in and hook up the hose
14. Connect up the heater hoses
15. Connect the upper and lower radiator hoses
16. Connect the brake booster hose to the intake manifold. It will be a bit of a reach this time as the location is slightly different
17. Connect the emissions hoses
18. Connect the throttle cable
19. Connect the clutch cable
20. Connect the speedometer drive cable or no VTEC!!! (You might not get it in right the first time usually it takes driving the car and messing with it a couple times to get it right!)
21. Bolt on the valve cover ground strap
22. Connect the return fuel line to the fuel pressure regulator
23. Connect the fuel line to the fuel rail
24. Bolt in the battery tray
25. Put the battery in
26. Put the intake tube back in. It will barely fit if you use the stock air box it is better to have an aftermarket intake at this point
27. Add coolant and water
28. Add oil to the motor
29. Add oil to the transmission
30. Put the splash shield on if you want to I didn’t
31. Put the hood back on
32. Put the wheels back on
33. Lower the car
34. Final tighten the lug nuts with the car on the ground
35. Connect the battery
36. Double check everything to see if it’s hooked up
37. Make sure the ground strap going to the valve cover is attached
38. Make sure the grounding point by the thermostat housing is attached or the car won’t start!!!
39. Triple check!
40. Turn the key to the run position to check for fuel leaks if there are address them accordingly don’t catch your car on fire cause you didn’t check!
41. Start the motor!!!
That wasn’t so bad and you still might even have some money left at this point. You should be able to hit mid 15’s in the quarter mile all day long now. Faster if you’re a good driver and your car is set up well. Don’t forget to check your lug nuts for tightness after about 100 miles of driving.
Wiring walk thru
First take a good look at the wiring diagrams I have added to this they will help you a lot and should keep you on the right track. When you read a pin number you will see that it will have a letter in front of the number which tells you what plug to look at i.e. “A12” So you would look at plug A for the correct harness and then find the 12th pin on that plug.
Pay close attention to the directions so you don’t get lost as you could damage the ECU or a sensor if you do not follow the directions. Read through all the steps before performing them so you have an idea of what is taking place before you dive into the wiring.
Step 1 is the grounding for the fuel injection relay and the ECU:
1. On the old ECU plugs cut off the wires going to pins number A9 and A10. They are both black.
2. Connect the wires from pins A9 and A10 together but keep in mind that two more wires need to be connected to them also
3. Look at the new ECU plugs now and find the wires coming from pins A23 and A24 make sure you have the right ones they are black
4. Connect the wires from pins A23 and A24 together but keep in mind that two more wires need to be connected to them also
5. Now connect the wires from pins A9 and A10 from the old ECU to the wires coming from pins A23 and A24 from the new ECU
Step 2 is the purge control solenoid signal:
1. On the new ECU plugs locate pin A20 it is a red wire that needs to be extended to reach the engine bay.
2. The wire it connects to is red, which goes directly to the purge control solenoid. It is one of the 14 wires you moved to the other side of the car when you modified the D16Z6 harness.
3. Just connect the two wires with whatever connectors you have chosen to use.
Step 3 is the fuel pump control signal:
1. On the old ECU plugs locate pins A14 and A15 and cut them off. They are green with a black stripe.
2. Connect the wires from pins A14 and A15 together but keep in mind that two more wires need to be connected to them also.
3. Look at the new ECU plugs now and find the wires coming from pins A7 and A8 make sure you have the right ones they are Green with a yellow stripe.
4. Connect the wires from pins A7 and A8 together but keep in mind that two more wires need to be connected to them also.
5. Now connect the wires from pins A14and A15 from the old ECU to the wires coming from pins A7 and A8 from the new ECU.
Step 4 is a “hot at all times” wire for the ECU from the under dash fuse box:
1. On the old ECU plugs locate pin B1 and cut it off. It is white with a green stripe.
2. On the new ECU plugs locate the wire coming off of pin D1 (White with a blue stripe) and splice it to the wire you cut from B1 on the old ECU plugs.
Step 5 is the radiator fan control signal:
1. On the old ECU plugs locate pin B12 and cut it off. It is yellow with a green stripe.
2. On the new ECU plugs locate the wire coming off of pin A12 (Yellow with a green stripe) and splice it to the wire you cut form B12 on the old ECU plugs.
Step 6 is the check engine light signal:
1. On the old ECU plugs locate pin B13 and cut it off. It is green with an orange stripe.
2. On the new ECU plugs locate the wire coming off of pin A13 (Green with a orange stripe) and splice it to the wire you cut from B13 on the old ECU plugs.
Step 7 is the start signal for the PGM-FI relay and ECU:
1. On the old ECU plugs locate pin B7 and cut it off. It is blue with a white stripe.
2. On the new ECU plugs locate the wire coming off of pin B9 (Blue with a white stripe) and splice it to the wire you cut from B7 on the old ECU plugs.
Step 8 is the speed sensor signal from the gauge cluster to the ECU:
1. On the old ECU plugs locate pin B18 and cut it off. It is yellow with a red stripe.
2. On the new ECU plugs locate the wire coming off of pin B10 (Yellow with a blue stripe) and splice it to the wire you cut from B18 on the old ECU plugs.
Step 9 is the electronic load detector signal:
1. On the old ECU plugs locate pin B10 and cut it off. It is green with a red stripe.
2. On the new ECU plugs locate the wire coming off of pin D10 (Green with a red stripe) and splice it to the wire you cut from B10 on the old ECU plugs.
Step 10 is the electronic air control valve signal:
1. On the new ECU plugs locate the wire coming off of pin A9 (Green with a white stripe) this wire needs to be extended to reach the wiring in the engine bay.
2. The wire it connects to is blue with a yellow stripe, which goes directly to the EACV. It is one of the 14 wires you moved to the other side of the car when you modified the D16Z6 harness
3. Just connect the two wires with whatever connectors you have chosen to use.
Step 11 is the power wire to junction C125:
1. On the old ECU plugs cut off the wires going to pins number A6 and A7.
They are both yellow with a black stripe.
2. Connect the wires from pins A6 and A7 together but keep in mind that
three more wires need to be connected to them also
3. Look at the new ECU plugs now and find the wires coming from pins A25 and B1 make sure you have the right ones they are yellow with a black stripe
4. Connect the wires from pins A25 and B1 together but keep in mind that
three more wires need to be connected to them also
5. Now connect the wires from pins A6 and A7 from the old ECU to the wires coming from pins A25 and B1 from the new ECU plugs while adding in a wire that's run from the connection you just made to the wire that it connects to in the engine bay which is a yellow with a black stripe wire and is the same wire you had to extend that is on junction C125. It is one of the 14 wires you moved to the other side of the car when you modified the D16Z6 harness.
Step 12 Make sure that the data link and check engine connectors are wired correctly. The main thing to check is that pin 2 on the three pin connector has the wire running to a power source. I have chosen pin D1 as it is easy to access and in the same area saving you from running a wire somewhere to get 12Vs.
Next is the wiring in the engine bay. Here are a few pictures that may help you understand where some of these connectors are located:
Step 13 is a ground wire:
1. On the C211 connector of the car’s wiring harness next to the strut tower and fuse box locate pin # 5 it is a black wire and cut it off.
2. Connect the wire you cut off to the black wire from the 14 wires you pulled from the other side of the D16Z6 harness.
Step 14 is the oil pressure sender wire:
1. On the C211 connector of the car’s wiring harness next to the strut tower and fuse box locate pin # 6 it is a yellow wire with a red stripe and cut it off.
2. Connect the wire you cut off to the yellow wire with a red stripe from the 14 wires you pulled from the other side of the D16Z6 harness.
Step 15 is the tachometer signal wire:
1. On the C211 connector of the car’s wiring harness next to the strut tower and fuse box locate pin # 8 it is a blue wire and cut it off.
2. Connect the wire you cut off to the blue wire from the 14 wires you pulled from the other side of the D16Z6 harness.
Step 16 is an alternator wire:
1. On the C211 connector of the car’s wiring harness next to the strut tower and fuse box locate pin # 1 it is a black wire with a yellow stripe and cut it off. Do not confuse this wire with the thick-gauged black wire with a yellow stripe that was described in steps 10 and 16 of the D16Z6 engine wiring harness preparation section!!! That wire is for the power to the distributor.
2. Connect the wire you cut off to the black wire with a yellow stripe from the 14 wires you pulled from the other side of the D16Z6 harness.
Step 17 is another alternator wire:
1. On the C211 connector of the car’s wiring harness next to the strut tower and fuse box locate pin # 2 it is a white wire with a blue stripe and cut it off.
2. Connect the wire you cut off to the white wire with a blue stripe from the 14 wires you pulled from the other side of the D16Z6 harness.
Step 18 is a back up switch wire:
1. On the C217 connector of the car’s wiring harness next to the strut tower and fuse box locate pin # 3 it is a yellow wire and cut it off.
2. Connect the wire you cut off to the yellow wire from the 14 wires you pulled from the other side of the D16Z6 harness.
Step 19 is another back up switch wire:
1. On the C217 connector of the car’s wiring harness next to the strut tower and fuse box locate pin # 6 it is a green wire with a black stripe and cut it off.
2. Connect the wire you cut off to the Green wire with the black stripe from the 14 wires you pulled from the other side of the D16Z6 harness.
Step 20 is the coolant temperature sender signal:
1. On the C211 connector of the car’s wiring harness next to the strut tower and fuse box locate pin # 7 it is a yellow wire with a green stripe and cut it off.
2. Connect the wire you cut off to the yellow wire with a green stripe from the 14 wires you pulled from the other side of the D16Z6 harness.
Step 21 is the coolant temperature switch:
1. On the C217 connector of the car's wiring harness next to the strut
tower and fuse box locate pin # 5 it is a yellow wire with a green stripe
and cut it off.
2. Connect the wire you cut off to the green wire from the 14 wires
you pulled from the other side of the D16Z6 harness
Step 22 is the vehicle speed sensor wiring:
1. These wires are not needed!!! They are the two wires left from the 14 your pulled from the other side of the D16Z6 harness. One is a yellow wire with a blue stripe and the other is yellow with a white stripe.
2. You could cut them off or leave them or burn them or whatever you want as you do not need them since you are using the vehicle speed sensor from the gauge cluster to tell the ECU how fast the car is traveling. That is why you must have the speedometer drive cable installed correctly or no VTEC and a code 17 for you to cry about. I went ahead and built them into only one side of the Molex connector in my car so they would be there if I decided to do anything with them in the future. Although I have had no use for them to date and probably never will I’m sure.
Step 23 is to copy steps 10 and 16 from the D16Z6 engine wiring harness section. It may be necessary to read some of the other steps to understand what is going on if you become confused.
That should do it for the wiring portion. Are you still wanting to do the swap? I hope so it isn’t as hard as it was to right this article that’s for sure! Good luck and have fun!
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Hybrid Mode
