Will an 84 ecu run an 83 engine

[James112]

Like the title says, just wondering if an 83 engine can be run off of an 84 ecu and wiring harness. If not does and 84 harness plug and play with an 83 ecu or will I need the harness, ecu and engine to all be the same year?

[4SFED]

Keep the ecu and wiring harness the same year. You can then make the engine work with that ecu/wiring harness. BTDT lots of times. You may have to change over some components/sensors/connectors on the engine to the year engine that was with the ecu/harness to match that ecu/harness.

[ndtoan85]

yes, it will work with no running problem or check engine light.... it even works with 85 ecu but will have engine light ON for knock sensor. all connectors plug in fine.

[James112]

Awesome, thanks for the replies.

[tyrantfour]

you could jb weld a knock sensor to the block to eliminate the cel with the 85 ecu and harness

[4SFED]

The main point is that a 5mge engine is a 5mge engine. As long as the ecu matches up with the engine wiring harness, you could for example make an '82 Supra 5mge engine work in a '88 Cressida using the correct harness, connectors and sensors (the '88's), or make an 85 5mge work in an 82 Supra if you use the 82 vacuum advance dizzy and the 82 harness, and disregard the 85's knock sensor, etc.

[Road Ripper]

The 85 ECU will not work with the earlier harnesses, because the knock sensor wire is gone and the TPS SENSOR is different. You could add a knock sensor wire (shielded) and an additional wire for the newer TPS, and also swap in an 85-86 TPS.

[4SFED]

One more time - keep the same year ecu matched up with the same year wiring harness and associated sensors, and you can make any year 5mge into the year you need.