Introduction to the conversion:

Are you wondering what does it take to convert a Civic Eg3 from carburetor to electronic fuel injection?

A bit of effort is the reply, but it’s worth every minute spent on it.

Why would you swap carburetors to fuel injection? Simply because it’s better in every aspect. 
It’s more controllable, it’s more efficient and will allow you to extract more power out of your engine simply by putting a better design intake, for example a d16z6 intake manifold.

Fuel injection conversion will also allow you to run the famous P28 ecu, (or P30 that is) which is tunable, so even more power can be extracted from the stock engine.

Fuel injected eg3
Civic eg3 fuel injected

Parts needed:

So, how do we start?

First off we, to convert a Civic Eg3 from carburetor to electronic fuel injection, make sure to have the following parts:

  • Civic Eg5 (D16Z6) Engine Harness
  • Civic Eg5 (D16Z6) Cabin Harness (only the front side of the harness, the one that goes from the engine bay fuse box to the ecu and then to the other fuse box under the steering wheel. No fuse boxes are needed since they’re the same. The main relay is needed but should be attached to the harness.
  • Civic Eg5 D16z6 Intake manifold or D16y8 intake manifold with throttle body, fuel rail, fuel injectors, fuel pressure regulator, idle air control valve, Air temperature sensor, throttle position sensor, Map sensor.
  • Civic Eg5 (i think any fuel injected civic Eg) Fuel tank with fuel pump and fuel level sensor preferably with complete fuel lines.
  • Civic Eg5 d16z6 P28 Chipped Ecu or any equivalent Ecu such as p30 of course chipped or with an Hondata installed.
  • New intake manifold gasket.
  • Civic Eg5 d16z6 or EK3 D15z6 distributor (i think that virtually any obd2a or obd1 distributor that bolts right in would work). I used an ek3 one since i had it lying around.
  • Something to put an air filter on! You can also use a stock Eg5 airbox or anything you like. I suggest a 63mm 45 degrees coupler, a 63mm straight aluminium tube and a 63mm pod filter.
  • Some spare wires + soldering iron + some electrical ability.

Now the fun begins:

Your Civic Eg3 from carburetor to electronic fuel injection conversion can now begin after you collected all the materials listed above.

To start, I suggest, after removing coolant from the system, to remove in this order: Battery, intake manifold, Engine wiring harness, Steering wheel, dashboard, heater core, internal wiring harness, rear seats, fuel tank and fuel lines.

To remove fuel lines, the procedure would be long and I think it would require you to drop subframe. Since fuel injection uses at least 3 bar of pressure, you cannot use carburetor fuel lines barbed hose fitting, that’s dangerous, don’t do it (little sidenote on this: I’ve seen factory cars coming with a barbed hose fitting and a worm clamp as Fuel line, but do that at your own risk. So if you dare, you could use your existing lines.).

In our case, to avoid dropping subframe, we used AN6 braided lines with 2  12mm banjo fittings, 1 for the pump and 1 for the rail and of course 1 filter in the middle.

You should end up with a D13 with a z6 intake, Obd1 distributor, Eg5 engine and cabin harness, a new tank with a pump and fuel lines to the rail installed.. 

Now what? First of all, since rear wiring wasn’t made for fuel injection, it doesn’t have a fuel pump electrical connection. You have to add 1 wire from the Main relay pin n7, yellow/green wire to the positive wire of the fuel pump, and add a ground to the other pin of the fuel pump connector.

You should now have a priming pump on ignition on and a car that could virtually start on a D16Z6 P28 base map but would be extremely rich and wouldn’t run any good. To run your Fuel injected EG3 you will now need a good base map for the fuel injection to work any good in your Eg3.

I can provide one, tested, which has the fuelling sorted, just get in contact with me.
What I’ve basically done is to use a D14A4 base map, sort fuel, sort ignition and removed unnecessary and unavailable features.

You can now add an adjustable cam gear to your D13 and start tuning on a dyno for good power. I expect it to be close to a tuned D14A4, which has proven to reach 100 Hp+ in NA configuration with breathing mods. You could also turbo it and make at least 160 Hp out of it.. 🙂

That’s all for it, thanks for reading and if you have any question, please contact me!