280Z EFI Inlet manifold ground wire

[EuroDat]

I took some photo's of my EFI manifold with the ground wire connecting to the frame for a fellow member.

This is the only ground I could find. The EFI harness doesn't have any grounds and seems to rely on this wire for grounding. I think mine is still the original ground wire.

Chas

[Captain Obvious]

Chas

The EFI harness does too have a ground. It runs one thick wire right over to the battery negative terminal. That's about as ground as it gets in an automotive application!

The ground you highlighted above is part of the engine bay wiring harness, and I've done a little poking around with it as well. You want to see something interesting? Disconnect both ends of that wire and then check the resistance to ground with them disconnected. Still makes connection, right?

There must be internal splices inside the engine bay wiring harness that are back feeding through other directions.

Same with the other ground connection on the other side of the engine. One end at the alternator, and another on the bulkhead wall near where the heater tubes poke through the firewall. Disconnect all four of those at the same time, and they STILL read to ground.

I didn't dig any further than that, but I found it interesting.

Don't forget that the whole drivetrain is connected right to the battery negative terminal through the starter cable too.

[EuroDat]

You are right Captain. I was half replying to a PM, but I couldn't send photo's via the PM system. What I meant was there is no ground to the manifold/engine in the EFI harness. The EFI system doesn't need it because the sensors all go back to the ECU and the ECU has a direct link to the battery running along the firewall just under the the bonnect.

Ifollowed the ground in the wiring diagragm. It seems to splaice off, but its hard to locate it in the car itself.

Chas

PS: Ill have a dig for the o-ring for the fuel pump and post back the size.

[madkaw]

That's the way I am wiring my megasquirt ECU now. The (FI)sensors all use the same ground wire(reference) and are tied together at the ECU--which in turn is grounded to the engine block.

[rcb280z]

Chas, thanks for posting that for me. I knew there was supposed to be a ground there but mine is missing! Don't know why but it is completely gone! I will make one. I started looking at everything after I found that my fuel pump was wired outside of the fuel pump circuit and this is one of the things I found....no ground from engine to chassis. Is it a big deal or not? Not sure but if Nissan had one in place I'm going to make sure it is there now.

[rcb280z]

Out of curiosity what is the yellow wire for with the red crimp connector?

[EuroDat]

Out of curiosity what is the yellow wire for with the red crimp connector?

If you follow it in the photo IMG_0074 it goes under the High-Tension leads behind the dizzy to the temperature guage sensor.

The PO has been playing with mine too. I don't know why he cut it and rejoined it or maybe the wiring at the sensor was damaged and he replaced it all the way back to there. He also replaced the injector conectors and done a rough job connecting the wiring back together.

Im slowing restoring all the front wiring loom. A lot of the wiring around the inlet manifold is hard and brittle where it goes into the terminals.

Chas

[EuroDat]

Bob,

I have a AFM with type: A31-625-000. Its a JECS.

Most of the AFM's for the 280Z have A11-600-000.

The ZX can have A11-618-427, A11-639-800 and no doubt more changes over the years.

The 3 Auto trans 280ZX's I have seen have A11-604-420

The turbo model uses the A18-000-040. Were does my A31 fit in all that???? Beats me.

The photo's are made on a smart phone a couple of years back and not all that clear because of the poor lighting.

Chas

[rcb280z]

Looks like it may be a remand AFM. I thought it to be a little different looking than mine. The black cover reminds me of a ZX AFM cover. I noticed it in pic 4 of post #1.

[rcb280z]

With PO's hacking into this, that, and the other on our cars you and I may be able to help each other out because we have the same car with production date 05/77 and our vin's are very close.

[superlen]

Per grounds... Yes, the wiring harness has splices in it. I have one completely unwrapped and I have been using it for HellFire Testing. Let me know if someone wants me to trace down a wire for them. I have hacked on it some & I'm not 100% what year it was from.

Within the next month, I'll need to disassemble and document better in gear up for the replacement harnesses I'll be offering so I'll have more information & a far better understanding of where the wires "physically" route at that time.

@Chas

I think all the NA AFMs from Z's and Zxs were calibrated the same from the factory. (there was differences in the fuel pump switch contacts and such of course, but the airflow vs voltage out is the same). The Turbo versions I *believe* have a different spring rate vs voltage output to accommodate the greater airflow. I'm just now beginning to test/understand these dynamics & I'm working from questionable starting points as to which AFMs have which calibrated numbers so if anyone has some more information on that, I would like to learn what you know.

I only have three AFMs in my possesion to test/compare to each other. If anyone has any extra ones lying about, I would like to beg/borrow/steal/buy for my testing. I don't care what the condition and a good sampling of units that people think are dead or are known to be flaky would be helpful to me. PM me. - thanks.

Len

[madkaw]

Len,

I think I have one from a 83 NA if you want to borrow.