gen 3 MR2 ECU running ST185

Smaay

Member
has anyone used a gen 3 MR2 ECU to run their car? the engine already has ST205 injectors. it looks like the MR2 has more sensors. will I be fighting a CEL?
 

zaluss

Member
Smaay":1g5itf9g said:
has anyone used a gen 3 MR2 ECU to run their car? the engine already has ST205 injectors. it looks like the MR2 has more sensors. will I be fighting a CEL?

Not sure if this helps but I use a gen3 MR2 ecu for my swap to defeat the pump code but I have a ST165. No codes.
 

Smaay

Member
pinoutsfixed.jpg


looking at this pinout and looking at 93 All-Trac engine control I have to change 2 pins!!!! thats it 2 pins.

Move FPR pin A-6 to C-16
Move PIM pin C-5 to C-2

It cant possibly be that easy
 

underscore

Well-known member
You also have to repin the engine side to run the new sensors, but I think that's about it. There's a few threads on here about it.
 

Smaay

Member
underscore":d5rnb72x said:
You also have to repin the engine side to run the new sensors, but I think that's about it. There's a few threads on here about it.

oh hell what new sensors? crap i need a 3rd gen MAP sensor dont I? but what other sensors?
 

Corey

Active member
There are a couple great gen 2 to 3 efi swap threads on www.mr2oc.com

You will need to repin the harness at the ecu or have a jumper harness made by berk technologies.

You'll also need a map, ignitor (rpm limit will be lower if not changed), iat sensor and manifold temp sensor. The mat and iat sensors can be wired into the AFM harness, with these wires being repinned at the ecu.

The mat can take the place of the cold start injector using an adapter plate.

You mentioned you already have 205 injectors.

I think that's all, I did this swap 4 years ago and it was the best upgrade I've ever done.
 

alltracman78

Active member
Easier to use the EGR wiring for the MAT sensor IMO.
It's 1 extra wire to swap at the ECU but that's easier than running the AFM wiring to the intake manifold.

If you have a 92/93 harness it's only a few wires [5?]. No need for a jumper.

I have a brand new Toyota harness and I didn't want to cut it up so I used O2 sensor wires to connect the new sensors to the existing harness.

IAT is the same one for the 5SFE and 7AFE. Igniter is the same as the newer 96^? 5SFE.
 

Smaay

Member
I already wired up an IAT in the intake manifold. car is running an an AEM V1 now. what signal is the MAT? Manifold temp?
 

Smaay

Member
ok its THAM, I dont see any reason the same signal cant feed both inputs? splice it to both. has anyone ever done this?
 

alltracman78

Active member
It might work. I don't know how much the ECU cares about the IAT signal.
But keep in mind it does compare the two. IAT is pre turbo and ic so it will be cooler. Or should be.

I would just wire one in, they're really easy to find.
 

Smaay

Member
I went back through my notes, On the 3rd gen i swapped in the G/Fs car, I dont think I even used THAM. I put the THA sensor in the intake manifold and thats it. Car runs like a bat outta hell. Maybe its not needed????
 

Smaay

Member
Well i got everything hooked up. I installed a 3rd gen igniter, added the THAM sensor. fired the car up and checked the timing. It was back to 5 degrees. moved it up to 10. car runs good, it idles really high 1700 RPM. then it settles down to 1100.

I lost the wideband because I installed a stock O2 in that position. The car doesnt seem to make much power. I dont have a boost gauge set up yet.
 
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