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Discussion Starter #1
To start off I did my swap about a year ago now. It was out of a 95 legacy so it has dual port heads. My car is an AT with 4.44 gears and I still have the original 2.5L ECM.

A few things I've noticed and wonder about or am maybe concerned with.
1. I noticed zero fuel economy difference from before and after. I was slightly hoping for at least 1mpg improvement as I read most people have economy gains from this swap which makes sense seeing as its smaller. Anyone who has done this swap have the same results or better?

2. I recently drove a 95 legacy with a 2.2 and noticed the tach shows redline at 5500 where as mine shows redline at 6300 or so. And if I go wide open it takes it at least to 6k before shifting. Am I over revving this 2.2?

I have ZERO issues with this engine and haven't regretted the swap for one second. My concern is if my current ECM allows for it to rev higher than it was engineered for? Or if I got an ECM from a 2.2 car if I would notice a slight economy gain but maybe with a slight power loss?
My local picknpull has these cars constantly so getting a new ECM will be a piece of cake. Curious if anyone has tried this and if its worth it or has zero effect.
 

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the problem with swapping the computer is that they made changes to the set up. the computer has to match the wiring harness in the car. so depending on what years you are dealing with swapping computers may throw a code.

but that does not mean the engine will not run nor does it mean you would not see better gas mileage. but since you do not have to swap the computers to swap the engines most folks do not , have not bothered. but for about 40 - 50 bucks you can try. i would get a computer from a ej22 car the same year as your car.

what year is your car?

i mentioned an ej22 swap to a local mechanic recently (subaru driver but not a subaru mechanic per se). he drives a turbo baja and he didn't know they would swap. he then asked, ''maf system? that would work''. apparently with a maf system the computer can compensate and adjust for the fuel air ratio.

i have not seen better fuel economy in my 97GT, but i never really drove before it made the swap. but for the longest time my mileage was so crappy i was about ready to sell it. then i learned my speedo was off. this makes it impossible to get an accurate measure of MPG. (not your problem.)

i have just finished swapping in tire that are a perfect match to my speedo. mileage is improved but not great. of course i have over 160k miles on the engine and i have never cleaned the IAC, EGR or run seafoam through it. i really should try at least one of these.

BUT i don't get good mileage in any of my cars. i'm beginning to think it is the way i drive.
 

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Maybe look into getting a computer tune done? Not sure I can really answer this one. :)
 

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Kirtydandra, I have the exact same swap as you in my 98 Outback and have not gotten any mpg increase either. However, I did find the following things helped out a lot with gas mileage:

1) Keep oil changed regularly in front and rear diff
2) Make sure your MAF sensor and TPS are adjusted/functioning properly. Neither was in my car. I bought a new MAF sensor at a yard for $20 and got a buddy of mine to adjust my TPS, big difference.
3) How you drive makes a big difference, as canubaru mentioned. For one tank I basically tried to keep the RPMs as close to 2K as possible (yes, this means driving like Granny) and I got 27 mpg. I usually get about 23.
4) I think original spec wheels and tires do make a difference. I'm running WRX wheels with bigger tires (more overall circumference than the original OB tires) and I think things would improve if I switched back to the 15s with 205/70 R15.
5) Probably goes without saying, but keep it tuned up with quality parts/fluids.

Let us know if you try the ECM swap, I'd be curious to see what happens!
 

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Discussion Starter #6
all very good ideas. i guess i should just be happy i always get from A to B without a worry. i do get around 23mpg so maybe i should stop complaining. i assumed that it would get better though i did the swao for reliability reasons.

an interesting thing i noticed using a Modys Genisys. when watching live data stream and selecting the 2.2L option my fuel trims are almost zero which is abolutely perfect. when selecting the 2.5L option when inputing vehicle info fuel trims read -7 to -13% so is this my ecu perfectly compensating for the smaller displacement? i also recently just passed emmission with very very low tailpipe nukbers which would lead me to believe it is running as it should.

good to know about the ecu harness change. is that from phase 1-2? or from model to model? would a 96 impreza 2.2 have the same ecu as a 96 legacy 2.2?

ill have to look closer at my tps that is a decent thought. i recall it definitely being in spec in general. does anyone have specific spec for a 96 outback? or i suppose i should say a 95 legacy as thats what my engine is from?

im keeping my eye out at my local picknpull. ecus only like $30 there. lately theyve had lots of ej25 cars though.

im really not complaing just more curious if im missing out on something. ha. thing runs absolutely amazing and gets up and goes a lot more than some people complain about. dont fix it if it aint broke right? now if only i can convince myself of that... :)
 

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i've swapped ECU's - no difference.

might be the 4.44 final drive.

gas mileage is dependent on a lot of things....gas...summer blends with ethanol, pure gas no ethanol, driving conditions, etc.

mountains and or city driving...anything more taxing, is going to have smaller gains that get washed out in a swap. if you're always cruising along at 60mph for 400 mile trips weekly in flat land during the winter with no A/C running - good chance you would have noticed a good jump in gas mileage. start deviating from that and the advantage will wash quickly.

on a 15 year old car it's easy to have dry caliper pins, dragging brakes, unadjusted e-brakes, original PCV valves, fuel filter, dirty valve seats, bleeding injectors...it's not new any more.
 

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The ej22 is not getting better mileage because it is working harder to move the Outback around - ? if ej22 outbacks had the same tranmission / FD ej25 outback had.

5500 rpms seems rather low for a ej22 redline - My '99 EJ222 OBS-t has a 6200 RPM redline, my ej22t Legacy SS shows a 6500 RPM redline & our old '96 ej22e OBS had a 6200 RPM redline...

Note 1: The ej22t has a downgraded valvtrain (non-roller rocker arms, 1mm SMALLER exhaust valves) vs N/A ej22e's & has a 6500 RPM redline - I read of someone revving a stock ej22t very high (8k+ (if my recollection is not failing me) w/o issues) so your 6300 RPM should be fine.

NOTE 2: Your ej22 can handle low pressure turbo boosting with no problems - this is a good option if you feel the need to outpower / TQ your old ej25 w/o the ej25 HG headaches...
 

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Discussion Starter #9
thanks grossgary now i wont waste my time and money with an ecu swap.

good to know about the rpms. that was worrying me a bit.

yes im sure 4.44 gears arent helping my economy but man are they nice offroad!

and i do know that the OE 95 legacy ej22 trans is much different than mine. i had to swap flexplates as my OB torque converter was a decent amount larger.
 
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