91 motor into an 87

[Hawaii87]

So my motor died and my friend gave me his old motor. (He's doing an S50 swap) Both are M20B25's. What all would I need to do this swap?

[Erick]

Edit: Eh... misinformation's a bitch. I keep forgetting '87s still had the older Motronic.

[AdamF 88iS]

Water pump and hoses are different and must be downgraded to the 87 style system.

Idle valve, intake boot, throttle body, fuel rail, and wiring harness are different but can be used on without swapping.

[Hawaii87]

parts-wise? nothing. I'd do timing belt, tensioner and waterpump while the donor motor is out.

Is there a difference in the Motronic units and the harnesses? Asking because just looking at them, they look to have different connectors on the motor.

[Erick]

Yes there is... look above. I read '87 but it didnt click that you had the older Motronic.

[James Crivellone]

Is there a difference in the Motronic units and the harnesses? Asking because just looking at them, they look to have different connectors on the motor.

The 87i harness is Motronic 1.1 - 1.3, same as the newer 88+ harness.

The ECU's interchange fine, so nothing is "older" about it.

Use the 87i harness on the motor, everything will fit fine on the injectors once you remove the injector harness rail.

You can use the 91 harness if you want, but you will need to rewire C104 into C101, which is dumb if you already have the 87i harness.

[benDASHDASH]

JC, what the flip were you doing lastnight?

[Hawaii87]

The 87i harness is Motronic 1.1 - 1.3, same as the newer 88+ harness.

The ECU's interchange fine, so nothing is "older" about it.

Use the 87i harness on the motor, everything will fit fine on the injectors once you remove the injector harness rail.

You can use the 91 harness if you want, but you will need to rewire C104 into C101, which is dumb if you already have the 87i harness.

Thanks for the info. I guess I'll have to take a closer look at the 87 harness and the 91 motor again this weekend. I hope it all works, so I can get the car back on the road.

[Hawaii87]

The 87i harness is Motronic 1.1 - 1.3, same as the newer 88+ harness.

The ECU's interchange fine, so nothing is "older" about it.

Use the 87i harness on the motor, everything will fit fine on the injectors once you remove the injector harness rail.

You can use the 91 harness if you want, but you will need to rewire C104 into C101, which is dumb if you already have the 87i harness.

So should I use the 87 harness with a 173 DME??? or keep my DME?

Thanks!

[StereoInstaller1]

I have a 173 DME in my '87is...
Swapped from a 153.

Luke