Couple comments, answers, etc:

Of the three thermostat housing sensors, the one on the left is crucial to the EFI. The middle one only has an impact on cold starts (controls the cold start injector), and the one on the right only controls the temperature gauge on the dash and has no effect on how the engine runs at all.

The ground wire leading from the AFM base to the distributor is not original. Shouldn''t cause any harm though.

Your ignition coil is not stock. I thought the 78 was the first year they did not employ the external resistor for the coil. You don't have a ballast, right?

The device on the underside of the BCDD is a solenoid valve that disables the BCDD when the car is sitting still.

Also be careful to not interchange the two connectors @Captain Obvious just mentioned. There is also a sub-harness that may have been mentioned in a previous thread that ties into that circuit. Two wires with bullet connectors wrapped in heat shrink laying on the intake.

Rockauto has a selection of coils. Probably meet spec. although they don't show them.

You might start planning for the ignition module to fail though. It's what they do.

Actually, some specs are there, I missed them. Pretty wide range. Looks like RockAuto is confused though on the ballast reistor. They list one for use with the "external resistor" even though, as CO pointed out, 1978 doesn't use it. It has the module with current limiting capability.

I'd just go down to Oreilly Auto with my meter and see what they're selling. (Edit - actually I'd probably just go to the wrecking yard with my meter. Coils are spendy at the parts stores!)

https://www.rockauto.com/en/moreinfo.php?pk=940830&cc=1209260&pt=7060&jsn=448

(what's a 200 scale?)

Edited July 23Jul 23 by Zed Head

https://www.rockauto.com/en/moreinfo.php?pk=9165864

Here’s the correct coil for a 78 model without a resistor from Rock Auto. Also available from other suppliers. Also comes with the rubber insulator to fit the OE bracket as well.

NGK p/n U1099

Edited July 23Jul 23 by Yarb

How do you know it's the correct coil? RockAuto doesn't show it as a choice.

https://www.rockauto.com/en/catalog/nissan,1978,280z,2.8l+l6,1209260,ignition,ignition+coil,7060

I originally researched it through NGK when I was restoring my engine back to factory specs. If you go on their site and search that U1099 p/n it lists it for vintage Datsun’s. The car ran perfectly with the coil and factory ignition.

Edited July 23Jul 23 by Yarb

The number does look familiar. But, unfortunately, when you search it, not much shows up. It's something that I've noticed recently, that many of the old sources that I was sure are out there on the web, seem to be missing. I think it might have something to do with the monetizing of the internet.

On top of that, the genius AI chatbots and their "overviews" cite posts from Reddit or forums like Ratsun as authoritative references. They just steal from the single source and post it as their own creation. The internet is getting really weird.

https://www.google.com/search?q=ngk+U1099

https://ratsun.net/topic/83046-1977-620-l20b-no-spark-condition-on-fuel-injection-conversion/

Who knows, All I can testify to is that it worked great on my car with no issues.

I think it's just where the internet is going. I did go to the NGKSparkPlugs site and look and nothing came up. I also searched for a coil for my truck and it did come up. The database for 1978 280Z was just empty.

There's probably an old NGK catalog in the back of somebody's parts store that has the listing. We might have to go back to paper.

https://ngksparkplugs.com/en/part-finder

But wait! I tried NGK.com (which oddly says that it is not associated with NGK Spark Plugs...so confusing.) and found it. But..it's Not Available. From them anyway. Watch out for counterfeits.

Okay, I'll stop now.

https://www.ngk.com/application/search

Interesting discussion. I'd like to find a coil that actually makes a claim as to what it's primary and secondary resistance is. I can find 1.5 ohm coils all over the place, but anything less than that is almost non-existent. I messaged a few people on ebay and asked if they could report back their readings. We'll see. I'm sure 1.5 ohms would be fine, but if I'm gunna pull the trigger and buy something, I'd rather get something that matches the FSM:

I hate to say it but I don't think that you can trust most aftermarket parts today. Everybody is buying from Asia and they probably don't want to get tied to a specification. The primary spec. on the only part that had a spec. was huge. It was 1978 when Nissan created their 0.84 - 1.02 spec. About a 17% range.

The Wells coil today, above, is 0.7 - 1.4. 50%. Not even close to the Nissan spec but they're selling it as a replacement.

https://www.made-in-china.com/quality-china-product/ignition_coil-4.html

Four E's Vietnam

Four E's Vietnam

Decade-long expertise in manufacturing premium Aftermarket Ignition Coils