I see the 600 has missing pin outs, whereas the 601 has all the pins. I did not look to see if they are all in use inside though.

1 minute ago, Terrapin Z said:

I see the 600 has missing pin outs, whereas the 601 has all the pins. I did not look to see if they are all in use inside though.

Interesting. I wonder if auto used additional sensors like for the full-throttle kickdown function.

There is definitely a different model for an automatic. Try to search for that chart here on this site. It’s out there.

It’s a chart that someone found and posted from 1975-78 with date codes. AT vs STD.

The chart is from a Nissan Technical Bulletin. It's in the Resource section, linked below.

The differences between the ECU's is covered pretty deeply in that thread. Pretty sure that I commented about how I had tried a range of years (all of them, I think) of ECU's in my car and they all worked just fine. I was a parts collector, back when parts were abundant, and used my car as a testing unit. Probably worth remembering that the main point of EFI in the 70's was emissions reduction. Seems reasonable (to me) to assume that the minor changes were for emissions. Also worth remembering that some of the things that Nissan put in the FSM's and wiring diagrams didn't actually exist in the cars.

https://www.classiczcars.com/files/file/16-ntb94-097-nissan-ecu-guide/

Here's a link to the thread again. (Those embedded links are easy to miss - hate 'em).

https://www.classiczcars.com/forums/topic/60678-what-are-the-facts-about-280z-ecu-compatibility-and-differences/

Should also say that it might be early to be buying an ECU. There are many possible reasons for the engine to die suddenly. Any loss of electrical power to certain components could cause it. I knew somebody with an 80's BMW that would do that. It was a fuse in the trunk that would get hot and lose connection. Took him forever to figure it out.

3 minutes ago, Zed Head said:

Should also say that it might be early to be buying an ECU. There are many possible reasons for the engine to die suddenly. Any loss of electrical power to certain components could cause it. I knew somebody with an 80's BMW that would do that. It was a fuse in the trunk that would get hot and lose connection. Took him forever to figure it out.

Arg, that's not what I wanted to hear haha

Check and make sure your fusible links are tight

Hello my Brother Cliff!!

2 hours ago, siteunseen said:

Check and make sure your fusible links are tight

Good suggestion - I just checked and they're tight and free of corrosion since the last time I sanded them.

Hi gang,

So I took the car out last night and noticed it's no longer idling at 14.2 but way up at 14.6 - 14.7 and is also weaker once it's in 'cruise mode' (tab not touching the idle enrichment or full-throttle pin in the TPS) than before the shut-off incident even though I hadn't changed anything.

In the past, moving the AFM's black gear 1-tooth to the lean side of the original factory position gets the idle to 13.8, turning another tooth (now 2-teeth past original position) gets you a 14.2 idle, and 3-teeth gets you a 14.7 idle. Interestingly, while I moved the black gear back to 1-tooth past original positioning, I get 13.8, but 2-teeth now goes to 14.7 at idle (instead of 14.2 how it behaved in the past when running properly).

I popped open the current ECU and nothing crazy jumps out at me (see below pics) damage-wise. That said, I did notice there is some clear stuff (looks like transparent glue) coming from one of the chips and each of the holes that don't have chips soldered through them have some sort of shiny polish to them (boxed in orange on the final two below pics). None of those things I noticed look fresh at all however (something that happened within the past week when the shut-off occurred).

EDIT: I remember last night noticing the dip stick wasn't fully in - when I popped it fully in, the car went down and idled at 14.2 for maybe 20 seconds but went back to 14.7 after that. I plugged the hole with my finger just to be sure it wasn't the dipstick's seal or it popping out, but noting changed and sat at 14.7 again so that must have been a fluke.

Any ideas?

Edited May 8May 8 by chaseincats

UPDATE: After driving it yesterday and it running lean per usual, I got out and while the engine was running, jiggled wiring and when I got to the connection between the ecu coolant temp sensor and main harness, the car stumbled. After that, it returned to the proper mixture (14.2 idle instead of 14.7) and it drove great/richer throughout the rev-range unlike before.

I got home and with a multimeter, noticed that if I jiggle that connection just right, that connection loses continuity.

I read that over 176 degrees, the ecu fully leans out the car (the car was fully warmed up to around 170 degrees at that time (I have a 170 degree thermostat instead of 180)). That said, the ECU leans out the car by the temp sensor providing less resistance rather than more to the ecu (my connectors were slightly dirty/loose which would provide more resistance which should have riched it I'd think).

I'm trying to figure out why jiggling that connection riched it instead of leaned out the car further.

Any ideas?

Edited May 10May 10 by chaseincats