77 280z ecu swapped from 810

[Gmctyphoon]

I have been going over the whole car recently. I checked the ecu connections and found it has been replaced at some point in the past. The ecu has junk yard writing on it. First indication I saw that it wasn't original.

The sticker says:
Part #- A11-602-240
For - L24

My car is a 77 280z 4-speed manual.

That seems to be from a 810 maxima.
Is this ecu ok to keep in the 280?

The reason I was checking things is because sometimes the car will stall. I installed a fuel pressure gauge after the filter. The fuel pressure slowly goes from 30psi while running, to 0 when it stalls randomly.

[Captain_Zeros]

A little bit of googling leads me to believe the 810 ECU has a slightly different pinout to the 280Z and 280ZX ecu, and another thing to check is if it has the O2 sensor that matches the ECU, if the O2 sensor and the ECU are mismatched it'll muck up your mix.

Edit: I found this by finding 810 guys who wanna swap in 280z ECUs/O2-sensors/distributors to gain power

[Zed Head]

1977 doesn't have the O2 sensor (they came in 79, I believe), so the 810 ECU will always be open loop unless someone modified your exhaust system. Captain Zero's point about the pinout is good, I'd be surprised that it plugs in. The FSM says Do Not plug old in to new or vice versa. Maybe they swapped harnesses also. Or maybe you have a Maxima L24 engine in your 280Z.

If you have an L28, another thing to consider would be that the full fuel enrichment curve of the ECU is designed for a smaller engine. I think that above a certain AFM vane position, the fuel enrichment is delivered off of an RPM-based map built in to the ECU. You'd probably be lean at full throttle.

But this wouldn't explain your fuel pressure dropping. Sounds like you're AFM fuel pump contact switch might be tripping. Could be a vacuum leak or just an idle that's too low.

[Gmctyphoon]

The ecu plug looks like it could have been changed. I'm going to go cut the tape and find out.

I'm 99% sure it's 100% org motor.

The fuel cut out is not the afm. I had the black cover off when it died and the fuel pump contact was fine. I even moved it done to be sure. I think it's the relay.

Update: ecu plug looks org. No splices at all. There should be a lot of black and green wires right?

Engine says L28 on block. No O2 sensor.

[Zed Head]

Well, maybe they swapped the other ends of the wires, for those minor changes that CO mentioned. Weird, maybe the PO was saving some money.

If you go back to the 280Z ECU, you want A11-600-000. But you'll want to check the pinout of your harness before using it.

On the fuel pressure, I had a fuel pump on a test stand that spun up fine to proper pressure initially but slowly stopped spinning as it warmed up. You might put a voltmeter on the pump leads and see if you're losing power or if it's just a bad pump or if you have a clog in the fuel tank. Or disconnect the small starter wire, turn the key to Start, and let the pump run while listening.

[Gmctyphoon]

I know the ecu is not the cause of the fuel cut-out, but I still want to fix it if it is not right. I have read that the ecu and afm should match. Is this necessary? What numbers do I need to match up on the afm and ecu? The lot numbers?

My afm says for l28, so that's alteast correct. And I still believe that the ecu harness is original, but I will conform with a pin out test.

One more question. Is the fuel pump relay the one directly above the ecu? The FSM says it is part of a big relay, the main relay, but I cannot locate it.

As far as the fuel pump goes I have run the pump without the engine running. Every time the pump sounds ok and it builds around 35 psi. I have done this numerous times. t runs at 30psi

[Zed Head]

Here's a guy selling a couple of ECU's - Ecu - Nissan : Datsun ZCar forum :Nissan Z Forum: 240Z to 370Z

The fuel pump relay and EFI relay are combined in to one, up to some time in 78, when I think that they might have split them up. It's a 1x1x2" silver box mounted above the hood latch handle. I had a 78 with the same relay as my 76.