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Old 05-31-2016, 12:22 AM   #1
AustinWood
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Default EJ203 instead of EJ253

i know someone on here has have to of done this... does anyone know the cost it would be to make a 2.0 ej203 motor run properly in a 06 impreza that has a 2.5i ej253 in it? The only reason i'm asking is because the average 2.0 is 800 and the average 2.5 is 1700. What parts would i need to replace to make it run without issues?

(It's non turbo)
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Old 05-31-2016, 06:08 PM   #2
GEE-OTTO
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By the time you add in the EJ203 ECU, exhaust manifold, cost of time to swap items for the intake side of life and sort which sensors are/arent needed btwn your US car and that JDM used engine youll be in for more than $1700. Also how can you tell if the JDM engine is any better or worse than the domestic one?

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Old 05-31-2016, 07:26 PM   #3
AustinWood
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I'm confused... are you saying a ej253 is US and a ej203 is JDM?
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Old 10-18-2016, 11:03 AM   #4
kidsol138
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Question

Quote:
Originally Posted by AustinWood View Post
I'm confused... are you saying a ej253 is US and a ej203 is JDM?

Yes form what I have read EJ253 is USDM as its the motor in my 99 Forester L and the EJ203 is in a JDM motor shop.

I am wondering if the JDM EJ203 from an 04 Impreza RS will work in my 99 EJ253 Forester L, Or is it truly like stated above that there is a huge hassle to get it to work. I have a knocking motor in my L right now and want to get t back running again.
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Old 10-18-2016, 11:54 AM   #5
rotaxmax3
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Ej20* is not just jdm, it's everywhere but the US. You guys like displacement so much lol.

Many people here in Norway have swapped ej25* NA engines into their ej20* NA cars, plugged in and driven off.
The ecu can manage to compensate that little difference no problem. Just get an engine from the same year and ull be good. (they swapped the whole shebang with intake, injectors and so on but no ecu swap)
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Old 10-18-2016, 01:17 PM   #6
kidsol138
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Quote:
Originally Posted by rotaxmax3 View Post
Ej20* is not just jdm, it's everywhere but the US. You guys like displacement so much lol.

Many people here in Norway have swapped ej25* NA engines into their ej20* NA cars, plugged in and driven off.
The ecu can manage to compensate that little difference no problem. Just get an engine from the same year and ull be good. (they swapped the whole shebang with intake, injectors and so on but no ecu swap)
I am looking to do the opposite of that as all the JDM motor shops only have EJ203's.
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Old 10-19-2016, 03:23 AM   #7
subi400
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Quote:
Originally Posted by AustinWood View Post
i know someone on here has have to of done this... does anyone know the cost it would be to make a 2.0 ej203 motor run properly in a 06 impreza that has a 2.5i ej253 in it? The only reason i'm asking is because the average 2.0 is 800 and the average 2.5 is 1700. What parts would i need to replace to make it run without issues?

(It's non turbo)
The main issue is the i-active vales found in the 06 plus impreza 2.5i here in the states. I believe the jdm ej203's have this for the sohc engines starting around the same time frame, but need to find some pictures, then try and figure out if it is the same as the 06 impreza 2.5i and beyond.
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Old 10-19-2016, 02:25 PM   #8
lpxltt
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Quote:
Originally Posted by kidsol138 View Post
Yes form what I have read EJ253 is USDM as its the motor in my 99 Forester L and the EJ203 is in a JDM motor shop.

I am wondering if the JDM EJ203 from an 04 Impreza RS will work in my 99 EJ253 Forester L, Or is it truly like stated above that there is a huge hassle to get it to work. I have a knocking motor in my L right now and want to get t back running again.
EJ253 is from newer cars. 05+ Imps and Legacy. Forget the cutoff for Foresters and Outbacks but I believe it is the same.

A 99 Forester should be an EJ251; however, a friend of mine has one with an EJ25D with what appears to be factory wiring so either the early run 99s could have had the 98 engine, or something did a REALLY good job swapping in the older engine and wiring into his car before he bought it. I have not found anyone else reporting this though.

Honestly, by the time you are done with all the swap headache, it will be easier just to run a refreshed EJ253.
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Old 09-16-2020, 07:21 PM   #9
Suby51891
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Quote:
Originally Posted by AustinWood View Post
i know someone on here has have to of done this... does anyone know the cost it would be to make a 2.0 ej203 motor run properly in a 06 impreza that has a 2.5i ej253 in it? The only reason i'm asking is because the average 2.0 is 800 and the average 2.5 is 1700. What parts would i need to replace to make it run without issues?

(It's non turbo)
Did you end up swapping in the ej203? I just did this swap and it runs and starts but my idle is high, like 1600 to 2k rpm. Then it fluctuates while driving. Do I need to swap the ecu for a different one? What am i missing here?? Someone please help
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Old 09-18-2020, 02:24 PM   #10
Suby51891
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Default Success!

Ok I finally have fully completed the swap. The car runs beautifully now, well except for the fact that the ecu won't let me rev passed 4k rpms. I'm going to buy an ecu with non avcs, and that'll fix that. As for the sporadic idle, I didn't pull and install the pcv valve from the ej253 onto the ej203. The ej203 has the pcv valve on the intake manifold and I swapped them. I installed and now she runs like a dream so the answer to this question is YES. THIS IS PRACTICALLY A DIRECT SWAP, for $1000 cheaper. Took me 1 and a half days to do the swap and approx $1k including engine, full clutch kit replacement, all fluids and spark plugs, intake and exhaust manifold gaskets, and non avcs ecu. If you want to do this swap and have questions message me and I'll do my best to get back to you as soon as possible. My email is [email protected]. Name is Justin. Thanks guys
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Old 10-20-2020, 11:25 PM   #11
NewSilverWRX
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Quote:
Originally Posted by Suby51891 View Post
Ok I finally have fully completed the swap. The car runs beautifully now, well except for the fact that the ecu won't let me rev passed 4k rpms. I'm going to buy an ecu with non avcs, and that'll fix that. As for the sporadic idle, I didn't pull and install the pcv valve from the ej253 onto the ej203. The ej203 has the pcv valve on the intake manifold and I swapped them. I installed and now she runs like a dream so the answer to this question is YES. THIS IS PRACTICALLY A DIRECT SWAP, for $1000 cheaper. Took me 1 and a half days to do the swap and approx $1k including engine, full clutch kit replacement, all fluids and spark plugs, intake and exhaust manifold gaskets, and non avcs ecu. If you want to do this swap and have questions message me and I'll do my best to get back to you as soon as possible. My email is [email protected]. Name is Justin. Thanks guys
Did you run into any issues with cam gears/cam sensors? I am considering this swap for an ej253 avls motor in a 2006 Forester. Shell has life left, but just doesn't make sense to put in a $2500 engine. Were there any specifics on the ej203 you used? Wondering what differences there might be. Also planning to just use the long block and swap the intake. Have you considered a reflash of the ecu with the right ROm from the JDM version?
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Old 04-03-2021, 12:17 PM   #12
joshyard
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Default Ej 203

so i just converted my impreza to 2.0 using the EJ203. I wanted to know what the horsepower of the motor is as im seeing limited info on it and some persons are saying 140HP while some saying 155HP. I have the Japspec ECU so im hoping to get more tuneablility out of my engine. can someone enlighten me?
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Old 04-19-2021, 01:37 AM   #13
arakakishinigami
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Default personal experience

i swapped an ej203 in my 03 forester and have been running it with no issues (outside of a ghost egr code) for ~40k miles.

i bought an 03 forester a few years ago and blew the engine within 1000 miles (i was young and dumb)

i did minimal research and purchased a jdm ej203 of same MY as my forester and got to work. i transferred my stock intake manifold + accessories + cam gears + harmonic balancer + the little footy gear thingy guy that goes behind the crank pulley (don’t remember what it’s called lol). i also had to remove the EGR pipe and plug the port on the back of the head because my original intake manifold didn’t have EGR.

two weeks after the swap i got a random EGR code (stock ECU and harness) that cleared itself as soon as i plugged in my SSM3 laptop via Denso DST-i interface and scanned the DTC.

other than that, it’s ran perfectly fine. noticeable loss in power, but my fuel mileage went up so i’ve got no complaints. it got me to and from everywhere i’ve needed to go. all i did with the imported long block was replace the valve covers and put a new timing belt/tensioner/WP/plugs/wires to make sure it would run alright.

hope this helps anyone that stumbled across this thread looking for answers on the swap. you don’t need to swap an ECU in, and if it’s running rough try putting your stock gears on the jdm long block.

mine literally fired up first try no knocks, no misfires, no issues.
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Old 02-04-2022, 10:36 AM   #14
volksjager
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Quote:
Originally Posted by Suby51891 View Post
Ok I finally have fully completed the swap. The car runs beautifully now, well except for the fact that the ecu won't let me rev passed 4k rpms. I'm going to buy an ecu with non avcs, and that'll fix that. As for the sporadic idle, I didn't pull and install the pcv valve from the ej253 onto the ej203. The ej203 has the pcv valve on the intake manifold and I swapped them. I installed and now she runs like a dream so the answer to this question is YES. THIS IS PRACTICALLY A DIRECT SWAP, for $1000 cheaper. Took me 1 and a half days to do the swap and approx $1k including engine, full clutch kit replacement, all fluids and spark plugs, intake and exhaust manifold gaskets, and non avcs ecu. If you want to do this swap and have questions message me and I'll do my best to get back to you as soon as possible. My email is [email protected]. Name is Justin. Thanks guys

which ECU did you use to eliminate the AVLS? did you have to swap or reprogram the EEPROM to the match key? i want to swap a non AVLS JDM EJ20 into a 2011 Impreza with a 2.5 ALVS, but cant have a check engine light to pass inspection in my state. i tried a Denso ECU out of 2005 non ALVS Legacy, but the pinout must be different as it wont even turn over - even after swapping the EEPROM chip.

Last edited by volksjager; 02-04-2022 at 02:14 PM.
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Old 02-04-2022, 12:01 PM   #15
benflynn
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Do y’all not have pullaparts?
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Old 02-04-2022, 12:03 PM   #16
benflynn
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When the eeprom is wrong it will start for a moment then cut off FYI
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Old 02-04-2022, 12:28 PM   #17
volksjager
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im in the US, all NA subarus after 2005 where AVLS here. a pullapart wont help finding a JDM ECU. that would have to be sourced from a JDM seller or ebay and i dont wont to buy a ton of them just to find they are wrong. swapping EEPROM is no problem for me,but i need a non AVLS ECU with the right pinout to start with.
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Old 02-04-2022, 01:50 PM   #18
benflynn
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Pull apart has ej25s, and if you are capable of converting a 203 to run n place of a 253, u can fix a busted 253 I’d think. I’d be hard pressed to work that hard to give up 40ft/lbs
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Old 02-04-2022, 02:13 PM   #19
volksjager
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the yards here in the northeast want over $2000 for filthy high mileage POS EJ253s. i can buy low mile super clean JDM EJ20s for $800. most of blown the EJ25s i see are beyond repair and even those that can be rebuilt it is not remotely cost effective. i dont care about the power loss. around here these are just simple A>B cars for soccer moms, or in this case an old lady.
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Old 10-27-2022, 10:12 AM   #20
JaloP
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Default Compatible Parts

Quote:
Originally Posted by arakakishinigami View Post
i swapped an ej203 in my 03 forester and have been running it with no issues (outside of a ghost egr code) for ~40k miles.

i bought an 03 forester a few years ago and blew the engine within 1000 miles (i was young and dumb)

i did minimal research and purchased a jdm ej203 of same MY as my forester and got to work. i transferred my stock intake manifold + accessories + cam gears + harmonic balancer + the little footy gear thingy guy that goes behind the crank pulley (don’t remember what it’s called lol). i also had to remove the EGR pipe and plug the port on the back of the head because my original intake manifold didn’t have EGR.

two weeks after the swap i got a random EGR code (stock ECU and harness) that cleared itself as soon as i plugged in my SSM3 laptop via Denso DST-i interface and scanned the DTC.

other than that, it’s ran perfectly fine. noticeable loss in power, but my fuel mileage went up so i’ve got no complaints. it got me to and from everywhere i’ve needed to go. all i did with the imported long block was replace the valve covers and put a new timing belt/tensioner/WP/plugs/wires to make sure it would run alright.

hope this helps anyone that stumbled across this thread looking for answers on the swap. you don’t need to swap an ECU in, and if it’s running rough try putting your stock gears on the jdm long block.

mine literally fired up first try no knocks, no misfires, no issues.

I'm doing this exact thing right now. Only question I had was on parts. IE: Is the timing belt the same (Same P/N), as well as all pulleys, water pump, oil filter, etc...? Pretty sure the long block is exactly the same just different compression.
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