Page 1 of 2

ej22 to ej25d swap...not as easy as it looks

Posted: Sat Mar 25, 2017 6:43 pm
by WRXish
It all started about a year ago when I decided it was time to do a major upgrade to the ej22e in my 1991 Legacy wagon. Much work had been done to brakes, suspension, interior and such and the engine is the last major upgrade step before visiting the bodyshop.

I did a fair amount of online research and all indications were that an EJ25D would be a bolt in swap for the EJ22 in the car and I could reuse 2.2 sensors and wiring and the ECU in the car would never know the difference. Or failing that, the ECU would learn the differences and fix them electrically. Without user intervention on my part. Sadly that is NOT how it works. Hence, the need for the comprehensive swap guide this document is to become. There is way too much information out there that is woefully incomplete, or downright misleading and knowing the truth from fiction is difficult without actually going through the somewhat painful process of making one of these swaps actually work properly.

In my part of the US, finding a good reputable shop to build an engine is easier said than done and I have no frame of reference for how hard it might be in other areas of the country. So suffice it to say, I did some hunting, selected a builder and roughly a year later took delivery of much less of a complete package than I wanted, but it was all he was willing to do. More on the builder later. I will call him out on his failings and screwups in this whole process without sparing his or anyone else's feelings. To say the process didn't go well is an understatement. We will get back to the issues with the work done later as they become important to the story.

Meanwhile, I am doing all the reading and studying on this project that I can and trying to formulate a plan for how to proceed with the swap. First of all, I determined that the 2.5 will fit just fine between the frame rails in a first gen legacy. So physical fit, and the ability to to bolt everything up is indeed possible but not exactly easy. And certain things do NOT fit and will require creative solutions.

I pre-ordered as many parts as I could ahead of time so I would have what I need to get the engine in the car in as short a time as possible. Among those parts were the EJ25 flywheel and clutch assembly to match the cable operated clutch that came in the car so I did not have to do a clutch type conversion. I knew I would need the coil and plug wire assembly for the 2.5 so that was pre ordered, as well as spark plugs and thermostat. I also ordered a bunch of 2.5 sensors that I wish I had not ordered. these include cam and crank sensors, water and oil temp sensors, IACV assembly for the 2.5 manifold. The reason I wish I had not ordered those items is simple, the 2.2 sensors off the old engine bolt right up and in some cases you MUST use the 2.2 parts if you are using the 2.2 wiring harness as the 2.5 wiring harness is different and the electrical connections on the 2.5 parts do not match exactly the 2.2 connections. To explain: The cam and crank position sensors on the 2.2 have their own cable attached that connects to the car wiring harness back at the transmission. Those will translate to the 2.5 just fine or did on my swap. The IACV from the 2.2 will not bolt up to the 2.5 manifold, so you are forced to use the 2.5 IACV but while it is electrically compatible with the 2.2 wiring by swapping the two outside wires going to its connector (you get a CEL if you dont swap the wires) the function of the IACV is not correct and the engine runs at a permanent fast idle. The only solution that I have found so far is to seal off the large vacuum port on the IACV and the hole in the intake tube where the IACV connects and have no fast idle capability. Not really a deal breaker, but it is inconvenient. At some point I will try to adapt the IACV that was on the 2.2 to the 2.5 intake and rewire the connector back to stock and get normal idle function back. But until some of the other problems that have surfaced are solved, that aint even on the back burner.
The coil wiring has to be changed too to have spark. Its fairly simple to do. I cut the connector off the first gen coil and a piece of the 2.5 wiring harness that isnt being used and made an adapter cable to correctly wire the 2nd gen coil to the first gen wiring harness. The result is a very hot spark and normal functioning coil. Just what we wanted. Match up the color codes on the 2.5 wiring harness to the 2.2 coil harness stub, plug it in and you are golden.
We used the 2.2 throttle body and throttle position sensor with no issues at all, bolts right up, and it works electrically with no hiccups.

We have some problems left to sort out and I will go into them now in no particular order.

1) I have a very fine running 3 cylinder engine. Seems that the number 2 cylinder is making no contribution to making power. Unplug the spark plug wire and idle speed does not change, I am getting spark, I have 180 psi cylinder pressure, but no power. Replaced spark plug with great difficulty, and that did nothing to solve the problem. Next step is fuel injector. If that fixes that problem then we are done with that issue and can move on to some of the other ones that remain unsolved. If that does NOT work, then drop the headers, unbolt motor mounts and jack engine up to get valve cover off and see if the valve train on the dead cylinder is working as intended. Lots of extra work so I am praying for the injector cure to work.

2) None of the fans seem to be working. The AC fan doesnt work because of an AC problem that we will get to next on this list. But the engine fans should cycle on when the engine is warm. They arent. They worked fine before and now they dont...dont know why and I will need help figuring it all out. Even with the obd1 diagnostic plugs connected the fans dont run...totally lost on that one.

3) The A/C is NOT going to work from your 91 on the 98 engine. Reason being, the compressor is too long to fit in its assigned location due to intake manifold interference. My solution is probably not the cheapest way to do it but I think it is the best way. Remove the old compressor and both hoses, one to the condenser coil and the other to the evaporator connection on the firewall. The 98 compressor is a much smaller unit and the mounting bracket is a much better design. The bracket integrates well with the rest of the engine accessories, alternator bolts right up to the newer style bracket. Now I need hoses that fit the new 98 compressor. The old ones will not work. The hose going to the firewall can come off of a 98 outback and it will fit and work. The other hose I am stumped on because of a difference in where the hose attaches on the 91 condenser is different than on the 98 condensor. Looks like a custom hose will be required there. So the AC remains an unfinished part of this project. If anyone has a creative solution to solve this problem other than what I am thinking, lay it on me. I am all ears.

The builder in this case has not been terribly helpful. I contracted with him to build a complete engine ready to put in the car, hook stuff up to and hopefully drive away. It was not delivered anywhere near complete. I wont divulge the builders name publicly but anyone who wants to know just pm me.

When I went to pick up the engine it was wrapped in plastic to protect it during transport. I should have unwrapped it on the spot and I would have immediately seen the first problem....the damned intake was installed backwards!!!! Really!!!! I also discovered the idler pulleys and tensioners on the timing belt were used items...so I took the engine back, and they replaced the used parts while I watched. I had already turned the intake around...he and I had a very frank discussion about the level of work delivered and the fact that it did not meet my expectations. He assured me that if their were additional problems he wanted to help resolve them. It remains to be seen just how willing he will be to get involved in it at this point. I am guessing that he will find it convenient to NOT be available for further work.

So the bottom line is I need help resolving some of the problems I am having particularly the fan thing and the AC issues...the dead cylinder issue will get resolved eventually I hope...until then I have a useless car. HELP

Re: ej22 to ej25d swap...not as easy as it looks

Posted: Sun Mar 26, 2017 4:01 pm
by beatersubi
I'm sorry to hear of your troubles. I've had the same experience with machine shops. They mostly seem to be focused on domestic stuff. It's worthwhile to find one familiar with import engines and Subaru, specifically.

Would it be very hard to make an adapter to mount the 2.2 IAC to the 2.5 manifold? That would be my suggestion.

Have you looked at the compatibility of the '98 condenser? If it will work with the '91 filter/dryer, that might be the easiest route.

Re: ej22 to ej25d swap...not as easy as it looks

Posted: Sun Mar 26, 2017 4:13 pm
by WRXish
many thanks to the suggestion for replacing the condenser with one from a 98. If it is still there, I will plan to go back to my local pic and pay tomorrow and snag that puppy and bring it home. Enough on the AC for now.

main problem seems to be at this point two separate things that are I suspect related. Let me explain. First, when I connect up the diagnostic plugs under the dash (both sets) and go to start the car, the CEL stays off. I know it should come on under those conditions. Also under those conditions the fans should run and they do not run. When I turn the key off, the CEL turns on briefly and then cycles off after a few seconds. I clearly have a serious issue there that must be resolved before I can consider the job finished. Additionally the dead number 2 cylinder continues to confound me. I have tried two different junk yard injectors and still nothing. I am wondering if there is some easy way to trace the injector signal back to its source and determine if it is getting the correct signal. I am truly at my wits end on this thing and need serious help. PLEASE HELP

Re: ej22 to ej25d swap...not as easy as it looks

Posted: Mon Mar 27, 2017 6:11 pm
by Legacy777
Without any of the diagnostic connectors connected does the CEL come on?

With just the GREEN connectors connected do you hear relays cycling on/off?

The ECU grounds itself through a spot on the back driver's of the intake manifold right around where it mates to the heads. Does the 2.5 manifold have this same setup? Are you using the 2.5 engine harness? If so, did you verify every single pin on that engine harness matched up with the existing 2.2 engine harness?

I suspect something related to the ECU ground is also why the fans are not working.

Re: ej22 to ej25d swap...not as easy as it looks

Posted: Wed Mar 29, 2017 1:22 am
by WRXish
Legacy777 wrote:Without any of the diagnostic connectors connected does the CEL come on?

With just the GREEN connectors connected do you hear relays cycling on/off?

The ECU grounds itself through a spot on the back driver's of the intake manifold right around where it mates to the heads. Does the 2.5 manifold have this same setup? Are you using the 2.5 engine harness? If so, did you verify every single pin on that engine harness matched up with the existing 2.2 engine harness?

I suspect something related to the ECU ground is also why the fans are not working.

Hi Josh, finally got here where i could read and respond to your post. I dont think there is the same ground on the 2.5 i will check when i get home.

The way it was behaving it would click the relays when u turn the key on but just once, no cel, didt matter if green or black diagnostic connectors were connected or not. really screwy i will send u a photo of the inside of the ecu so u can see what was fried. With luck, new ecu arrives friday, maybe get it going this weekend thanks for your help Josh

Re: ej22 to ej25d swap...not as easy as it looks

Posted: Wed Mar 29, 2017 1:39 am
by Legacy777
If you get no CEL at any point then yes either the ECU is fried or there is a power or ground issue.

Re: ej22 to ej25d swap...not as easy as it looks

Posted: Wed Mar 29, 2017 4:40 am
by WRXish
Now that I have complied with the new security requirements I can actually log in...Apparently I have or had a missing ground that routed much of the current the engine uses through the ground path in the ECU nearly frying the wiring harness as well as smoking the ECU. Next step is to figure out if there are any ground connections missing and fix them, test the wiring harness for hidden shorts or opens, hook up the new ECU and hope for the best. God what a pain this has been....and it may not be over yet. Hopefully my experience will encourage folks to be vewwy vewwy kehhfull to avoid the same scenario.

Re: ej22 to ej25d swap...not as easy as it looks

Posted: Wed Mar 29, 2017 4:43 am
by WRXish
the wires affected were the black, black-white, white and one more I cant remember all connected at top end of the bottom connector on the ECU. Circuit board and conductors were cooked, wires vaporized, circuit board turned to charcoal over the area of about a dime. not what you want to do at all.

Re: ej22 to ej25d swap...not as easy as it looks

Posted: Wed Mar 29, 2017 5:31 pm
by Legacy777
That is not good to hear :(

Re: ej22 to ej25d swap...not as easy as it looks

Posted: Sun Apr 02, 2017 1:58 am
by WRXish
Thanks Josh for the help you have offered with this situation. I discovered much to my chagrin that both the main wiring harness that connects to the ECU from the engine harness and the engine harness itself were both cooked. There is some good news in all of this as I dived into the arduous task of repairing the engine harness first I discovered that the part of harness where the short occured was the wiring going to the IACV. And while I am sure my repair of the harness will prove to be sound and long lasting, it raises some other questions that I dont know enough to answer. The engine I swapped into my wagon is a 25d that came from an automatic car. The engine that came out of my wagon had the old first gen IACV which only has two wires active, a white and black wire going to the outside pins on the connector. Those were the two wires that burned, It also burned the yellow red wire that goes to the center pin on the automatic 2nd gen cars. I repaired all three burned wires and now am confident that the cause of burning up the ECU has been handled, but I still have a fried black wire in the main harness which I intend to replace with a new wire but I am NOT disassembling the main harness. Gonna run that sucker next to the main harness into the under dash area cut the burned wire in the main harness at both ends and hook up the new wire, giving the juice a new path to run. I did a test of the adjacent wires from the same connector and found no internal wiring harness shorts as a result of the fried black wire. So the plan is to take that wire totally out of the picture by removing all power to it from both ends. My first question to you is does this sound like a good plan?

The next question relates to IACV wiring. If I understand correctly the automatic cars use all 3 wires and the manual tranny cars use just the white and black, at least on the first gen IACV. Is that also true on the 2nd gen IACV? Or do I have it all wrong?

And then, does using a second gen IACV with the 3 wire connection work on a first gen manual tranny car that only had a 2 wire IACV? Bear in mind the wiring harness has all 3 wires but the first gen iacv only has the two outside pins for connection leaving the center connector floating. And then finally, will connecting the 3rd wire up on a manual tranny car create an electrical problem by either confusing the ECU or causing extra heavy current flow through the black and white wires? The last thing I want is to fry another ECU and burn up my pretty new repaired harness. I am frankly a bit gunshy at this point because there are too many things I just dont know.

Re: ej22 to ej25d swap...not as easy as it looks

Posted: Mon Apr 03, 2017 5:18 pm
by Legacy777
As for your plan of adding a replacement wire along the existing harness I think that sounds fine. I would wrap the wire in electrical tap along the harness or put new wiring loom around it.

Here's the background on the IAC valves. The 90-91 MT non-turbo Legacies with the Hitachi ECU's are the only one's with the two-wire reciprocating IAC valve. The 90-91 AT non-turbo Legacies, all 92-94 MT & AT non-turbo Legacies, and all 91-94 MT & AT turbo Legacies utilize the three-wire rotary IAC valve. The main difference between the reciprocating and rotary valve is that the reciprocating valve uses a spring to close it vs. the rotary valve having both opening and closing controlled by the ECU.

See the wiring diagram below.

https://main.experiencetherave.com/suba ... C_diag.jpg


The engine will not care what type of IAC valve is used as long as the ECU and wiring match the IAC valve that was intended for that ECU.

I'm not sure if answered all your questions and if not, please let me know.

Re: ej22 to ej25d swap...not as easy as it looks

Posted: Tue Apr 04, 2017 7:51 pm
by Legacy777
Tom,

I'm copy and pasting your email into this post so others can follow along in the future.
WRXish wrote:Hi Josh, Tom here, I get what you are saying about the two and 3 wire being for manual and auto, and the rotary type and plunger type being different. Part of the problem is the plunger type wont fit the 98 intake manifold because of intereference where the coolant pipes exit the body of the IAC. So the only kind that will work electrically for my manual 91 with its factory ecu is the plunger type two wire model and it wont physically mount up. I am looking at maybe some way to mod the IAC or other things on the engine to make it work. I hope I dont mess it up cause I cant get a new one from subaru, its no longer offered.


The wiring harness was repaired by strapping the replacement wire for the single fried black wire to the top of the main body harness but sheathed in shrink wrap just slightly loose on the wire. Not really loose, just not super tight. Everything is tie wrapped back down so its snug, and there is reasonable assurance that all is well inside the main harness, I used a 10 meg/volt ohmeter to check for partial continuity between the burned wire and the adjacent wires and found no evidence that it had melted anything together. To be certain I didnt have a problem in the future I cut both ends of the fried wire and tied them off under tape and ran its replacement wire as explained above. I got the engine started today and the electrically all seems well. The engine is not running well and I suspect a major vacuum leak. I can hear something but have not been able to isolate it yet. Ran out of time today. Will be back in it tomorrow hopefully finding the leak and getting the IACV issue resolved or at least a plan for resolving it. Cant wait to get this thing going...


Tom


hey thanks for your help, you confirmed what I had figured about the IAC being 2 wire for manual and 3 wire for auto, what I didnt know was that the 91 manuals MUST use the two wire plunger type because they match the ECU. So now I must find a way to mount it. That makes the direction clear, now to find the path lol.

Tom,

To clarify, you are NOT limited to the plunger type IAC valve for your 91 Legacy or engine configuration. Only the ECU needs to match. So you can get a JECS ECU (one of the other that use the rotary IAC valve) and convert over to the rotary IAC valve. The only other thing that would need to be swapped would be the MAF sensor and most likely the injectors. The Hitachi ECU's used the silver metal body MAF sensors while the JECS ECU's used the black plastic MAF sensors. The injectors all flowed around the same amount, however were of different styles and types.

When I did my AWD & 5MT swap I swapped ECU's to the 92 JECS ECU which had the red injectors vs. the gray injectors. When just swapping the ECU I found that I was using more fuel and the car wasn't as "snappy". When swapping in the matching red injectors my fuel economy increased the "snappiness" was back.

So I think you have options, you'll just need to decide which is the best route for you.

Re: ej22 to ej25d swap...not as easy as it looks

Posted: Wed Apr 05, 2017 5:52 am
by WRXish
Hi Josh, just picked up a new set of red injectors, not installed yet. The engine is running now, on all four cylinders, I have some details to finish up before I declare the car anything like road ready. I drove it to town today and it didnt overheat, puke all its coolant or complain too much. Butt dyno says I got a good bump up from the stock 2.2, but it does have a few issues I have to sort out and figure out. The IACV is back burnered for now. I have a rotary type mounted to the manifold but disconnected electrically since I have the hitachi ecu. The coil off the original iacv that came on the car is hooked up to avoid a check engine light. I started the car and warmed it up and twisted the vane in the rotary iacv till I had a good reasonable idle speed then locked the screws down on the IACV. So far so good. I adapted the 98 style torque box and intake tube to fit my homebrew CAI. Basically I have the 2.2 MAF housing boilted to velocity stack inside a cone filter and that hooks to the stock 98 torque box. Seems to run pretty good like that. Might find the stock filter box off the 98 would be better but I had to start somewhere. I have a few new rattles I think from tweaked exhaust during the engine swap. And a pesky coolant leak right at tthe thermostat housing. Grrr, dont wanna drain it again... But if I have to I will. The two repaired wiring harnesses seem to be doing ok thank God. And I have a peculiar problem....the hood latch cable has shrunk...seriously it is too short so that in warm weather it will not latch. Spent 2 hours screwing around with that thing today trying to figure why it would not latch...the cable is so short the latch mechanism is held off its normal resting place by 3/8 ". Still have to button up the under dash area where I was rewiring the main wiring harnes...dont ever wanna do that again or have anything to do with bodywork. :)

I'm not sure the fueling for the engine is right but some of the misfire issues may be related to loose plug wires I discovered when I got back from town today. So another test tomorrow and the if the wires dont stay put tomorrow, its a new set of wires along with rtv for the coolant leak. The fun continues :)

Re: ej22 to ej25d swap...not as easy as it looks

Posted: Wed Apr 05, 2017 4:04 pm
by WRXish
Update to last nights post...I was truly impaired when I posted all of that. Call it celebratory or whatever you want. :) Just re-read some of what you were saying about making the ecu and iacv match and a question or two about all of that occured to me. As it stands I have the Hitachi ECU and the coil part to that IACV hooked up to avoid a CEL. How would I even go about finding the JECS type ECU. Mostly to get the correct parts I have had to give VIN number as a part of the info provided to a parts person. Naturally, I dont have a VIN for a car that has the other type of ECU. Lets assume I can find one and then utilize the rotaryIACV I already have mounted on the engine. The original 2.2 in the car had black injectors, the 2.5 that is in the car has red injectors, I am assuming I want to stay with the red ones because they are what work for a NA 2.5. The 2.2 injectors are shorter and I dont think they will physically fit into the 98 fuel rails. I took one of the 2.2 rails apart and got a 2.5 rail from my local pic and pay and compared them the rails are different the injectors are too. So at least for the initial setup red headed injectors are what I have. Besides they match the color of the intake manifold and color coordination here has to be worth at least 25 hp. ;) So aside from my morning silliness, I guess I need to know more about the various ECUs and of course their availability. And while I am thinking about it. These are plug and play ECU changes right? By that I mean the wiring on a 90-91 ECU with two wire IAC is the same as the 92-94 ECU that goes with the 3 wire IAC, so its a matter of unplugging old ecu, plugging in new ecu, hooking up the 3 wire IAC and possibly changing injectors to something other than what I have now and I have a working system? Can it be that easy (lol)?

Re: ej22 to ej25d swap...not as easy as it looks

Posted: Wed Apr 05, 2017 5:29 pm
by Legacy777
WRXish wrote: And I have a peculiar problem....the hood latch cable has shrunk...seriously it is too short so that in warm weather it will not latch. Spent 2 hours screwing around with that thing today trying to figure why it would not latch...the cable is so short the latch mechanism is held off its normal resting place by 3/8 ". Still have to button up the under dash area where I was rewiring the main wiring harnes...dont ever wanna do that again or have anything to do with bodywork. :)
Regarding the cable, it runs along the wiring loom on the driver's side of the front fender so if you've moved or jostled around the loom at all in the fender well or under the dash that could be the cause of your hood latch cable issues.

Re: ej22 to ej25d swap...not as easy as it looks

Posted: Wed Apr 05, 2017 5:42 pm
by Legacy777
WRXish wrote:Update to last nights post...I was truly impaired when I posted all of that. Call it celebratory or whatever you want. :) Just re-read some of what you were saying about making the ecu and iacv match and a question or two about all of that occured to me. As it stands I have the Hitachi ECU and the coil part to that IACV hooked up to avoid a CEL. How would I even go about finding the JECS type ECU. Mostly to get the correct parts I have had to give VIN number as a part of the info provided to a parts person. Naturally, I dont have a VIN for a car that has the other type of ECU. Lets assume I can find one and then utilize the rotaryIACV I already have mounted on the engine. The original 2.2 in the car had black injectors, the 2.5 that is in the car has red injectors, I am assuming I want to stay with the red ones because they are what work for a NA 2.5. The 2.2 injectors are shorter and I dont think they will physically fit into the 98 fuel rails. I took one of the 2.2 rails apart and got a 2.5 rail from my local pic and pay and compared them the rails are different the injectors are too. So at least for the initial setup red headed injectors are what I have. Besides they match the color of the intake manifold and color coordination here has to be worth at least 25 hp. ;) So aside from my morning silliness, I guess I need to know more about the various ECUs and of course their availability. And while I am thinking about it. These are plug and play ECU changes right? By that I mean the wiring on a 90-91 ECU with two wire IAC is the same as the 92-94 ECU that goes with the 3 wire IAC, so its a matter of unplugging old ecu, plugging in new ecu, hooking up the 3 wire IAC and possibly changing injectors to something other than what I have now and I have a working system? Can it be that easy (lol)?

Regarding the ECU, I will point you to this thread with info about manuals/etc. Within that thread you will find this thread with the full parts catalog. The parts catalog lists out all the ECU's & part #'s on page 176 of 1265. The part # isn't that all important other than to try and verify what ECU the car came from if you have a random ECU. You want to find a JECS ECU and they came on 90-91 AT non-turbo Legacies and 92-94 AT & MT non-turbo Legacies. In terms of plug and play I would recommend trying to find one from a 90-91 AT non-turbo. I probably have one if you can't find one locally and want to give mine a try.

You would need to verify that you have the correct wires present for the three wire IAC valve, 2 from the ECU and one from a 12v switched power source. There are some other minor wiring differences between the model years (mainly 90-91 vs. 92-94). The caveat to that though is the injectors. If you have the red injectors I think/hoping you have you'll want to use a 92-94 ECU since that would match the injectors so you don't end up with the running slightly rich issue I experienced when changing injectors. Again, I think I have a 92 ECU. The main difference in wiring was that the AT/MT identifier pin was wired backwards. If you don't have a wire to that pin you'd have to add one. If you did have a wire there you'd have to snip it. Additionally, if you go with the JECS ECU you'd need to use the plastic JECS MAF sensor.

Regarding the injectors, can you take/post a picture of the injectors that you are using?

Thanks

Re: ej22 to ej25d swap...not as easy as it looks

Posted: Thu Apr 06, 2017 5:04 am
by WRXish
Ok got good idle and good light throttle driveability. 1/2 to full throttle not so much. stumbles, misses erratically. If it were a steady miss I would suspect a plug or plug wire, but its totally random. Wonder the the stock fuel pump cant keep up with the red top injectors? Guess I got to get a pressure gage and figure out how to hook it up inline and see what I am getting fuel pressure wise. Anyone know what is required for healthy fueling? The other thing that occured to me was to change out the red top injectors for the black top units that were in the 2.2 engine, not sure the injectors will fit the fuel rails though and I cant use the rails from the 2.2 the spacing is wrong on the injectors. HELP

Re: ej22 to ej25d swap...not as easy as it looks

Posted: Thu Apr 06, 2017 1:31 pm
by WRXish
Regarding your post Josh, I do have the red top injectors as that is what was stock on the 98. I know I cannot swap fuel rails between the old 2.2 and 2.5 because spacing and bolt layout is wrong but not sure about putting the black top injectors from the 2.2 in the 2.5 rail. Dont know if they will fit or not but seems easier to me to go that route and less expensive than buying yet another ecu and a mafs sensor and trying to figure out if there are any wiring differences. Without having the car the JECS ecu came off of there is no way for me to tell if the transmission signal leads are in the same place as my car. The wiring kerfuffle is a mess I would prefer to avoid if at all possible. Otherwise, I would have been better converting to obd2 and getting to do a bunch of wiring. If picking the wiring apart and doing a new ecu and mafs is the only reasonable option, please say so. And thanks again for helping :)

Re: ej22 to ej25d swap...not as easy as it looks

Posted: Thu Apr 06, 2017 6:06 pm
by Legacy777
Regarding the injectors, you need to match the injectors with the ECU, and here's what I can tell you about that. The part # for the red top injectors that fit the 92-94 Legacy is 16611AA140 & 16611AA141. Those part numbers supersede up to 16611AA310. That is the part number of the injectors from the 98 Legacy EJ25D motor. So what that confirms to me is that you could use a 92-94 Legacy ECU to work with those injectors and IAC valve and ultimately be the best solution in the long run to get everything functioning properly. You can get the ECU and MAF used from members on the BBS for cheap. I've got both just sitting around so I'm more than happy to help you out if you decide to go down that route and can't find any other options close by.


If you really wanted to try the old 2.2 injectors I don't think they'll work in the 98 rails. However, check out this thread for a possible solution.

viewtopic.php?f=5&t=55948


Regarding the wiring, it's just one wire and very easy to determine. You'd just look at a specific pin on the ECU wiring connector.

Re: ej22 to ej25d swap...not as easy as it looks

Posted: Thu Apr 06, 2017 7:47 pm
by WRXish
ok Josh PLEASE send me your ECU and maf. Swapping that out will be easier than changing injectors. And on top of that if it is just one pin that needs to be cut or connected, I can manage that I think. I am ready for things on this project to start going my way instead of murphys law way. How much do you want for those parts and how quickly can you get them shipped? And if I still have to replace injectors on top of that I will consider that an acceptable trade for a decent running engine. Please text me 434-907-6981 with your asking price for the parts. Many thanks for your help.

BTW I did try mounting the 2.2 injectors in the 2.5 rails....not even close to being the right size.

Re: ej22 to ej25d swap...not as easy as it looks

Posted: Thu Apr 06, 2017 8:21 pm
by WRXish
I noticed that you gave me two part numbers for those injectors is there any significant difference between thee aa140 and aa141? I have already received a new set of injectors of the aa140 part number so those should be totally compatible with your ECU and MAF. I so hope this works....

Re: ej22 to ej25d swap...not as easy as it looks

Posted: Thu Apr 06, 2017 11:19 pm
by Legacy777
WRXish wrote:I noticed that you gave me two part numbers for those injectors is there any significant difference between thee aa140 and aa141? I have already received a new set of injectors of the aa140 part number so those should be totally compatible with your ECU and MAF. I so hope this works....
There should be no real appreciable difference between the two. Subaru changes part numbers for sometimes small details, but both those part number role up to the latest part number so they are compatible/interchangeable.


I'll get in touch with you about the parts.

Re: ej22 to ej25d swap...not as easy as it looks

Posted: Sat Apr 08, 2017 8:51 pm
by WRXish
Hi Josh, new MAF (one I had on hand) and IACV and new ECU are installed. Havent driven the car yet, but it appears we lucked out and got a manual transmission ECU. So no surgery needs to be done there. However, have a strange thing happening. With the car warmed up and idling I have a check engine light code 24 for IACV. Not sure how or why that is. It also causes the engine to behave strangely. Start it up and let it idle, and for a few seconds it seems normal then the idle speed starts increasing on its own up to about 15-1600 rpm hangs their a few seconds, CEL comes on and the idle drops back to something approaching normal....any ideas whats going on? I will be most curious to hear your take on it. Meanwhile, while I am waiting for your response to this I am going to finish buttoning up the ECU and go for a short test drive and see if it is running well now. It revs up cleanly no hint of roughness or misfire but of course that is under no load. But it is very responsive to throttle, it feels like what I believe it should feel like. I will return here with a followup post

Re: ej22 to ej25d swap...not as easy as it looks

Posted: Sat Apr 08, 2017 11:38 pm
by WRXish
Ok The car runs better, but I think there is quite a bit left in it that I am not getting. The hard misfires and stumbling at mid throttle are gone. Solved the IAC code it through by hooking up a second iacv coil to the wiring harness and leaving the one on the manifold disconnected electrically. No more code 24 and it idles just fine. Still needs something just not sure what...I guess I will drive it a while until I figure out what to try next. Thanks to you Josh for your help and guidance and service info I did not have access to. A true friend.

Re: ej22 to ej25d swap...not as easy as it looks

Posted: Mon Apr 10, 2017 5:19 am
by WRXish
It still stumbles just a bit at mid throttle, I am guessing it is right at the edge of going into open loop mode. I am thinking I might get better results by throwing away the CAI I have attached to the MAF and going back to the factory box. Plus it looks more stock that way. hehe It seems like it is just a wee bit lean at mid throttle and while that might be great for gas mileage I would rather have better throttle response than max fuel economy. Especially if I could go back to the CAI later for road trips where a few more mpg would be appreciated. I am thinking that part of the fueling issue is related to the ecu expecting the stock airbox and the CAI is throwing things a bit lean. Anyone think that is reasonable?