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Guest Message by DevFuse

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Upgrade EJ25 2nd gen from OTB 97 to a EJ25 3rd gen

Engine swap engine upgarde EJ25 upgrade EJ25 2nd gen to 3rd gen

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3 replies to this topic

#1 Khan017



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  • Sydney, New south Wales

Posted 09 July 2013 - 09:43 PM

Hello All,


I have a OTB 97 2nd gen witha very dead motor! 


I just want to know how hard is it to upgrade to a EJ25 3rd gen motor


I have heard you have to remove the wiring harness and such.


#2 idosubaru


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Posted 10 July 2013 - 12:39 AM

yes, that will be a MAP instead of MAF (like your 97) engine.  so the wiring and air sensing is all different.  basically you want to migrate the wiring harness from the 97 intake onto the newer engine. 


Gloyale has commented numerous times on doing a Phase I - Phase II swap - but i can't recall which direction (I into a II or II into a I).  he said the main issue is with idle control.  swapping harnesses gets you a car that won't idle so just step on the gas.  find his posts about it for direct info.

#3 johnceggleston


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Posted 10 July 2013 - 07:18 AM

as mentioned, it is not a straight , easy swap.

you could end up with a CEL that you can not correct which would prohibit the car from passing inspection in some places.

i would look for a good engine from your gen, 96 - 98/9.



but if the 3rd gen engine is cheap / free, i would use the block and bolt on your heads, intake, and cam / crank sprockets.

#4 Gloyale


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Posted 20 July 2013 - 02:11 PM

You can swap all the 97 intake wiring harness over to the newer engines intake.  You may have to spice the injector connectors, or slice the alignment tabs off them.  You will need to swap throttle bodies (use the 97 and it's TPS).  Likely will need to make a plate that bolts between the TB and the intake, that extends up a bit to block off the IAC portion of the newer intake..


The rest is PCV routing which may need an adapter to fit the newer block vent?  But otherwise the same.


You may also need to swap the Crank and Cam sprockets with the triggers......Depends on what is on the new engine, but they need to match the 97 style, or be switched.

Also tagged with one or more of these keywords: Engine swap, engine upgarde, EJ25 upgrade, EJ25 2nd gen to 3rd gen

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