View Full Version : 4th Gen Swap

Ballroom Heros
09-25-2006, 03:05 AM
Hey everyone, here's the deal. I have an 86 GTS. I just ordered a 90-93 Mr2 3sgte. My main concern is adapting the wiring. I know some of the obvious things like the harness is RHD going in a LHD chassis and that the chassis has a cable speedo and the new motor is electronic. I'd like to know some of the other wiring problems I'm going to encounter. I've done alot of searching here on CelicaTech and on other forums and haven't found anything directly addressing this. I've done some complex swaps on other cars also, so feel free to get into details. Also, if anyone who has done this swap could provide some first-hand advice to take some of the guesswork out of this, that would be great. Thanks - Matt

Ballroom Heros
09-27-2006, 03:32 AM

09-27-2006, 04:18 AM
Well,a ST185 front clip would have been a better choice than getting a MR2 turbo motor. Is the motor going to come with EVERYTHING? for example: a complete un-cut wiring harness,all the sensors, ECU, etc.

First thing that you will need to do is put the alternator and power steering pump brackets from your 3SGE onto the MR2 turbo motor.

You can also use the MR2 turbo tranny if it is coming with the motor. But you will need vital parts from either a all-trac,V6 camry/solara, or Rav4 5-speed tranny to convert the shifter linkage to the correct side of the tranny to work in a FWD setup. you will also need to source ST165 mounting hardware to mount the MR2 turbo tranny. And you will need ST185 outer axles and MR2 turbo inner axles to put together hybrid axles. Also if the tranny has a Electric speed sensor on it then you can simply switch it out with any cable driven speed sensor from a all-trac,V6 camry or Rav4 tranny.

If you try to use your 3sge tranny you will run into a problem with the starter. it will hit the exhaust manifold of the MR2 turbo motor. so using your 3sge tranny may be out of the question unless you use a belhousing from a 5SFE tranny then it will work. But i say if you have a MR2 turbo tranny
use that. Or you could just pick up a 5SFE tranny and use that.

The cable driven speed sensor is not that big of a problem. you dont have to have a electric speed sensor for the ECU to work. if you wire everything correctly the ECU will still get a signal from the sensor in your speedometer even if you still have a cable driven speedometer.

The wiring wont be easy but it wont be really hard. You could always send the harness from your 3sge and the harness of the MR2 turbo to "Dr.Tweak"
He is good at fusing harnesses together.

good luck with the swap.

Ballroom Heros
09-28-2006, 12:22 AM
Yes, the swap comes with everything. Yes, I am using the MR2 trans. I'm not using power steering. Thanks for all the info. I'll post up some pics after it's in.

09-28-2006, 06:13 AM

09-28-2006, 09:24 AM
This would be better placed in the FI forums.

Ballroom Heros
10-07-2006, 02:15 AM
Ok, the engine is here. Basically nothing matches up between the engine and the chassis. My question is should I keep the MR2 harness on the motor an make it work with the chassis OR take the original 3sge harness that plugs into all the chassis plugs fine and de-pin the MR2 ecu hookups, put them into the corresponding wires on the celica harness and then run any extra wires that the MR2 has seperate? Thanks.

91 celica st
10-07-2006, 02:42 AM
do the harnesses while ther eboth out of the car, makes is soooo much easyer, basically take the new 3sgte harness and wire in your 3sge stuff like fuzebox and lengthen the wires that need to be lengthened...its not that difficuilt if you have the wiring diagrams

god i wish i had them when i swapped

Ballroom Heros
10-07-2006, 06:25 AM
Yeah, so far tonight, I pulled the one recangular white plug out of the MR2 fuse box and I am matching the wires to the celica plug that runs the gauge cluster. Then I'm gonna deal with combining the starting/charging systems. That should pretty much finish up the wiring.