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How to: Gen2 to Gen4 swap

56K views 54 replies 33 participants last post by  MR2_Turbulence 
#1 ·
I have always loved the MR2 community for the time people take to share knowledge and make something like changing a timing belt or removing an engine seem feasible for the garage tinkerer. If you have the tools, space and know-how to remove your engine and do large maintenance items like a clutch and timing belt, this swap isn't too difficult. If you don't feel comfortable doing this yourself it would be wise to let professionals like Prime, ATS, TCS, etc. do the swap before you end up with a never-ending project.

And just a heads up, I'm not going to go into every detail here. I'm just going to cover some of the most common questions I've received through PM and address little hang ups that I encountered. I'm going to reference other sites for how-tos because I'm lazy. I'm also assuming you have the BGB for referencing torque values. I welcome additions, comments, criticism -- just post your addition or opinion on other methods for everyone's benefit.

Download your BGBs and wiring diagrams now: http://www.mr2oc.com/showpost.php?p=3737624&postcount=70

Here is a post from Aaron at Lithia Toyota with some part numbers for maintenance items as well as a link to ToyoDIY. If you find a part number in ToyoDIY and it appears in Lithia's online parts catalog, I've found most times you can order it.

http://www.mr2oc.com/showthread.php?t=401375&highlight=gen3+timing+belt

http://www.toyodiy.com/parts/q.html

I started with a 91 Turbo. It's last state of modification was a built Gen2 project that I abandoned. I kept the LSD E153, ACT 6 puck clutch and lightweight flywheel, A2W IC and parted the rest of it out to fund the Gen4 swap. To me, the allure of this engine is that it's simply a newer model 3SGTE that gives a good bang for the buck if prices remain low. I had already sunk the expense of the intercooler, turbo kit and exhaust, so obviously those are additional expenses if you start from stock.

What I received, a 1998 ST215 with automatic 4wd transmission, engine harness and ECU. This seems to be the most common swap. It may be possible to swap cases with the FWD transmission, but I wouldn't know where to tell you to begin.



 
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#36 ·
I think this should further answer your question, daddylomglegs used an "adaptor" harness which outputs factory sensor readings thru the factory harness, reroutes them, and sends the signals to the new pin on the aftermarket or repurposed ecu.

If you have specific questions about your setup, send me a Pm and I'll let you know what I suggest for your setup.
 
#34 ·
If I were to use mr220v's wiring harness and an aftermarket ECU like the ATS Racing EMU could I order the bare engine? Buying the motor without the transmission, wiring harness, and ECU would save me money on the purchase price and on shipping. This would be going in to a 1993 MR2 with the stock Gen 2.
 
#35 ·
I'm not aware of 220vs complete product offering, but I don't know anybody who makes a completely aftermarket engine harness. He is more than likely
Modifying factory harnesses and requiring a core charge, and also making "jumper" harnesses that plug into the stock engine harness and have outputs specific to the ecu.

ATS makes their own adaptor harness but of course requires a factory harness.

Obviously the transmission is irrelevant and if you're running an aftermarket ecu (like an AEM, Haltec, ATS, etc) you don't need a factory ecu. However,
If it's a "piggyback" like an AEM FIC, you'll need a factory ecu.
 
#38 · (Edited)
Let me know what questions you have when you come to them. John may be able to answer better, but ATSScott just had a batch of prototype coolant neck adaptors back from the machine shop a couple weeks ago. I will confirm (none of this stuff existed when I did my Gen4 swap back in 2006) but I beleive he has devised a way to use the Gen2 water neck on the Gen4 coolant inlet saving you from having to source a potentially expensive ($175?) gen3 water neck.

EDIT: Here you go; $50 instead of $175. http://atsracing.net/Parts/Details/E-CLT-NECK-ADAPTER



 
#48 ·
So to put a list of what you would need (from 1991T model specifically):

Throttle cable
Gen4 Downpipe
Fuel lines
Water neck or adapter
Modify engine hook (grind it or reuse 5S)
Reuse Alternator, crank pulley, ac compressor and starter for 3S



Do you need any MAP sensor or does that suppose to come with the engine from engine importer. Any other electronic components which are not on the engine itself?

Thank you.
 
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