Can 1988/89 ECU install into 1986/87 3G?

[Euphoria]

I got a problem of my 1987 Hatchback LXi, the ECU can't give a signal to main relay (pin 8) when igniting, it caused the engine can NOT start. I checked the fuel pump, injector, main relay, wires and everything were all right except the ECU. I swap my spare 1986/87 ECU which caused the same result. Can't strat my Hatchback.

Can I use the 1988/89 ECU to my 1986/87? Whcih is all performed for LXi level. I found they had different model name on the ECU but totally same connecting inlets.

[Strugglebucket]

you can't swap them, they are different. might be able to rig it to run but it would throw codes.
are you sure it's not the main relay that's bad? it seems unlikely that both your ecu's are bad.

[Euphoria]

Thanks!
I have replaced three main relay to test it, also changed the current main relay to another 1989 3G LXi and works very well. The final way to ensure my spare 86/87 ECU is to test on a 1987 3G LXi, which is very little quantity here.

I also doubt how could two ECUs be failed? It's very few possibility like this.

[Vanilla Sky]

it could be your coil. i had that problem with my car. replaced the coil and it worked.

[frankie89]

hey i think its da main relay, i had the same problem, and i swaped an ecu but of the same year 89 and i got the same code...so i just changed the main relay, and put in a acura relay..it has been working great for 3 years now..but you might need a computer diagnostic check of the ecu and relay system..

[Euphoria]

I had checked the main relay by following service manual and the results was good! Also, I replace another main relay from 1989 3G 4D LXi, and my hatchback still not work.

I had followed service manual to check main relay, fuel pumpers, injectors and distributors, all works fine but couldn't start. I'm running out the ideals for my hatchback ........

[Euphoria]

I've solved the problem as I found one injector (near driver side) which was leakage seriously. I replaced the new O-ring & washer for all four injectors, including the leakage one. The engine now could be started smoothly.