1.8 ecu running 2.2

[scottzg]

So, what would be involved in using a 1.8 ecu to power a 2.2? Will it run lean open loop? Can one take a 1.8 powered car, drop in a 2.2 engine, plug in a 2.2 ecu, and swap to 2.2 sensors and drive away?

[vrg3]

What year Impreza?

Our cars use mass-flow engine management, so fueling will always be more or less correct, as long as you're not reaching the limits of the MAF sensor or fuel injectors. So if you use the entire EJ18 engine management system (i.e. don't mix an EJ18 ECU with EJ22 injectors), fuel should be okay.

But, ignition control will be suboptimal. For one thing, the correct ignition timing at any given load and RPM is different for EJ18s and EJ22s. But also, load calculations will be somewhat inflated as the EJ22 generally consumes more air than an EJ18. Also, at least some years the EJ18 had no knock sensor, and so no ability to learn ignition timing or to adapt to bad fuel or whatever.

It'd probably work out though.

The EJ22 ECU won't plug in in place of the EJ18 ECU, but it could be wired in. You'd use some of the stock EJ18 stuff, like the cam and crank position sensors, and some of the stock EJ22 stuff, like the injectors and MAF (if different). You may need to add wires for stuff like the idle switch and knock sensor.

[THAWA]

Also note that the EJ18 uses air injection, or something, so you probably wont be able to just throw an EJ22 in there and be done with it.

[scottzg]

err 95 impreza. What about leaving the mani and sensors and ecu for the ej18 and throwing in the ej22 longblock?

Thx for the info!

[MConte05]

Bumping this up again from the dead since it's the only topic that directly addresses this.

I have read that the 1.8ECU can run a 2.2 better at high RPMs due to a more aggressive timing map. I have a stock 1997 Impreza 2.2 engine running high RPM delta cams since it is used in my rally car. I see sustained high RPM (never drops below 4k rpm) on the stages, and curious if dropping in a 1.8 ECU would be worth the effort.

Topic is almost 7 years old, so maybe some new life has come out of this?

[mike-tracy]

The 1.8 doesn't have a knock sensor, so if anything the timing would be more conservative to protect itself, right?

[kimokalihi]

That's what I've read. People run the 1.8 ECU on the franken engine to help avoid detonation because the 1.8 is less agressive with timing due to not having a knock sensor. But I don't know much about it. Search NASIOC. I saw a thread about it recently on there with matt monson I think talking about this.

[MConte05]

The 1.8 doesn't have a knock sensor, so if anything the timing would be more conservative to protect itself, right?

But the head/piston/fueling design might be different that it isn't "aggressive" on a 1.8 setup, but when put on a 2.2L setup, it is aggressive for that particular setup.

Does anyone know what the timing is at high RPM and load on a 2.2 vs a 1.8? That published anywhere?

[Legacy777]

I would second the suggestion trying to search or contact Matt Monson.