JDM ECU on USDM engine

[joejoe69]

i am thinking of running a JDM V3 STi ECU on my EJ18T engine. i sat and compared the connector pinouts and found that they are just about identical. all i need to do is match and swap wires to the right terminals on the JDM ECU connector. however, the only thing that got me wondering is if i can run this ECU on a SOHC application (since JDM is DOHC). will i need a matching DOHC pulley from the same ECU? also, i am running an AVCR controller on my car, i don't have worry about wiring a boost solenoid to the ecu right?

can someone with knowledge chime in with your thoughts...

[2slo4u]

Count the teeth on your sohc intake cam and compare it with someone who's got a jdm dohc, it should work. People run dohc 2.5 n/a's on sohc 1.8 ecu's, I did. You could use the avcr but the ecu might throw a code if it doesn't see a boost solenoid connected.

[joejoe69]

can a usdm boost solenoid work in place of a jdm one?

i can source one for cheap since alot of wrx/sti owners swap'em out for GM 3-port solenoids and such.

[turboed22]

Make sure you are using the same injectors as the V3

[joejoe69]

yep, 550cc's already running on the EJ18T.

[MyScooby]

umm interestin . so if 1.8T run with JDM ECU, we dont need emanage at all?

[elislider]

the only way it would really work CORRECTLY is if you fully recreated all the parts of the jdm engine in your 1.8 T setup. the v3 jdm sti ecu is very aggressively tuned (6S ecu?) and if you arent careful you will EASILY blow your engine. its expecting 96 octane and has a 7900 redline w/8250 fuel cut which nothing except the jdm sti heads can handle. it would be super easy to blow an engine running a different ecu (especially one that is such a huge jump to very aggressively tuned)

one nice thing about the jdm v3/4 ecus is that they use the same ecu plugs as the usdm 1.8 so a simple repin and youre almost ready to go on the stock harness. still need to add in boost controller and a few other things but the harness is about 85% exactly the same (except for being physically arranged differently in the engine bay because NA vs turbo the harness is redirected to the other side of the car mostly)

[joejoe69]

Originally Posted by elislider

the only way it would really work CORRECTLY is if you fully recreated all the parts of the jdm engine in your 1.8 T setup. the v3 jdm sti ecu is very aggressively tuned (6S ecu?) and if you arent careful you will EASILY blow your engine. its expecting 96 octane and has a 7900 redline w/8250 fuel cut which nothing except the jdm sti heads can handle. it would be super easy to blow an engine running a different ecu (especially one that is such a huge jump to very aggressively tuned)

one nice thing about the jdm v3/4 ecus is that they use the same ecu plugs as the usdm 1.8 so a simple repin and youre almost ready to go on the stock harness. still need to add in boost controller and a few other things but the harness is about 85% exactly the same (except for being physically arranged differently in the engine bay because NA vs turbo the harness is redirected to the other side of the car mostly)

yes, 6S is the one i'm looking at, to be exact. how aggressive IS the ecu other than the higher redline and 96 octane requirement? (we also have 100 octane here in hawaii, 50/50 with 92 = 96.5) for my tuning, i'm already adding 10-15 degrees timing advance in some areas. and i'm thinking if I do go that route, I can always pull back timing to save my motor. I might lose a little power but it's better than the 1.8L USDM ecu.

as far as the heads go, the EJ22T redlines at 7K-ish. I think going 1K over with the 22T heads on my setup won't hurt it. i'll see if I can 'guinea pig' it too see if it works.

[elislider]

the mechanical rocker nature of the SOHC heads means they really just cant physically keep up above 7000 or 7500 rpm. thats why the real v3 jdm sti heads are shim under bucket DOHC design which can actually handle an 8250 rpm fuel cut. even a v3 jdm wrx is shim over bucket (like a 98 usdm 2.5RS) and cant handle as high of revs as shim under bucket

i have the 6S ecu on my v3 jdm sti swap and im running 92 octane but i dont take it above 5000 rpm to be safe (waiting on a powerfc in the mail right now). the 6S ecu is, from everything ive read, one of the most aggressively tuned ecus from the factory. it is very advanced timing already to the point that if you are running something other than what it expects (engine parts-wise, heads, injectors, etc) then you are very likely to blow something

also i dont know what you mean about tuning, you cant tune these older ecus, not unless you have engine management. and if you have engine management just get a plug-and-play powerfc or vipec

[joejoe69]

the mechanical part of it, i can understand now, i've asked other sources.

as far as tuning it, is there absolutely no way of pulling timing back on these ecu's? if the timing maps are advanced to allow high octane, why not retard it to allow lower octane? if i remember, these are obd1 ecu's which are easier to tune....or does it not matter?