1 hour ago, Zed Head said:

Since it's under the white cover you could just punch the wire through from the bottom, put a new terminal on it, and glue it in. Nobody will know but you.

I had the same idea as I was drifting off to sleep last night.

Had a couple minutes today, so I tried it out. Was able to get one terminal “free” without cutting any wires. Felt like a surgeon with my dremel tool. Looks like it’s going to work decently well. I’ll prolly pour epoxy into the void I dug out after I crimp on a new spade. I’ll post pics when I finish…

I know I'm jumping around all over the place, but trust me, I'm staying organized!

The AFM. Man, been doing a lot of reading, and I want to get thoughts.

Here's mine, freshly opened up. As far as I could tell, I didn't see any signs of anyone having been in here before. All glue blobs in place. I followed the atlantic Z writeup and measured resistance across the pins he mentioned. Everything checked out OK. It all looks pretty good in here, except for one thing, the coil spring "back stop" for the weight. Mine is not making any connect with the weight when in the fully closed position. Here's a pic of what I mean...

I wanted to get input before just bending the spring back to make contact. Is that the right move here? Also, unless you guys see something obvious, my plan is to just seal it up and make no changes because it appears to be untouched and I know this could have an effect on my smog readings.

Secondly, the AFM bypass adjustment screw appears to have been played with. Mine is 7 turns out from the bottom. I wonder if there's a factory spec for this, and if it being a CA car makes a difference...

Edited July 17Jul 17 by kcpope

12 hours ago, kcpope said:

I wanted to get input before just bending the spring back to make contact. Is that the right move here? Also, unless you guys see something obvious, my plan is to just seal it up and make no changes because it appears to be untouched

Yeah, if you think you are the first person to be in there and nobody has messed with it before, then I would close it back up and not change anything. You could move that "back stop" spring if you really wanted to, but I'm not sure it would gain you anything. I'd probably just leave it be.

I had a similar thought. I can't remember if that stop is actually contacted in a normal/unmolested AFM . Would be interesting to see other AFM's.

The vane itself has rubber bumpers on it, I believe. With the engine running neither "stop" is in use, air flow keeps the vane open.

When I was adjusting my AFM to pass emissions I found that the best way was to screw the screw out until you get some effect/stumbling, then screw it back in to a steady RPM. Screwing it out leans things, in makes it richer. In Oregon we got free trips through the emissions station though, so you could tune on the fly. Only downside was waiting in line.

A couple updates...

Got the fusible link holder spades repair done...

A 1/8 tungsten dremel bit was the tool for the job. As soon as you get about a 1/2 inch down into the plastic, you can start pushing the wire up through the bottom of the base.

Crimped on new spades. Yep, they're not quite as big as the originals, but i connected the fusible links to them, and the connection seems pretty solid.

Filled the void created by the dremel with JB plastic epoxy. Not the prettiest finished product, but it's functional. I can always come back in the future and splice in a completely new unit if I really want all the spades to match. At least the caps will cover it...

I also went around and cleaned up all the electrical connections and grounds I could find in the engine compartment. I got these small scotch brite wheels for my dremel tool and they cleaned everything up nice and bright! Better than using a nail file…

I put some of the D100L on each connection. It claims to remove oxidation and protect/improve all electrical connections. Cheap insurance...

Another previous owner suprise I found. No biggie, but as I’ve read elseware, all these little sub-par electrical connections can add up to a poor running condition. This one is for the fusible link coming off the positive battery terminal. Just twist em together and tape it up! Oof…

Lastly, I gently persuaded the spring “backstop” back into place and it’s working properly now. Took very little effort. Other than that, I put some rubbing alcohol on a q-tip and cleaned up the contact trace and sealed it back up. I'm leaving the idle air bypass screw at 7 turns out from the bottom. Zed, in a previous thread of yours, you mentioned a decent rule of thumb being...if you remove your oil cap at idle and the engine doesn't stumble, you're too rich. I'll use that as a guide to "tune" this screw before taking it in to smog...

I'm going to see if I can find a 3D print file for those fusible link covers...

Edited July 20Jul 20 by kcpope

Nice work.

A good rule of thumb: If you're bored and have some time to work on your Z, but don't have a specific project in mind.... Clean some connectors. 🙂

I was having some trouble with the AFM on my ’77 280z a couple of months back and compiled some of my research int a post here on ClassicZcars. Maybe it’s an interesting read to help you along or have trouble again in the future.

Baseline was that the car ran rich no matter what I did and along my journey I replaced every sensor before finding out the carbon tracks inside the AFM had breaks in it. I ended up replacing mine with a 7 pin AFM from a 90’s Ford probe / Mazda 626. That AFM is a bit bigger then the stock Datsun unit but the rubbers will fit over it and tightening the spring a couple teeth brought the AFR readings back into spec. the car still runs a little rich on idle but the emissions where pretty low for a late 70’s car and she drives perfect with good AFR readings while driving.

Edited July 20Jul 20 by Mitchel0407
Forgot the link

8 hours ago, Mitchel0407 said:

I was having some trouble with the AFM on my ’77 280z a couple of months back and compiled some of my research int a post here on ClassicZcars. Maybe it’s an interesting read to help you along or have trouble again in the future.

Baseline was that the car ran rich no matter what I did and along my journey I replaced every sensor before finding out the carbon tracks inside the AFM had breaks in it. I ended up replacing mine with a 7 pin AFM from a 90’s Ford probe / Mazda 626. That AFM is a bit bigger then the stock Datsun unit but the rubbers will fit over it and tightening the spring a couple teeth brought the AFR readings back into spec. the car still runs a little rich on idle but the emissions where pretty low for a late 70’s car and she drives perfect with good AFR readings while driving.

Appreciate you sharing. That was a great read, and I'll keep it in mind should I need to crack the AFM open again. 👍

I bought a rebuilt AFM from MotorSport Auto and found that it was too rich at idle to pass emissions. I could open the bypass up all the way and it was still too rich. I had to reinstall an old used one that came on a 78 parts car. Something to be aware of. That was in 2009. No idea what today's rebult AFMs are like.

Edited July 20Jul 20 by Zed Head
he > the

On 7/20/2026 at 9:36 AM, Zed Head said:

I bought a rebuilt AFM from MotorSport Auto and found that it was too rich at idle to pass emissions. I could open the bypass up all the way and it was still too rich. I had to reinstall an old used one that came on a 78 parts car. Something to be aware of. That was in 2009. No idea what today's rebult AFMs are like.

Yep, I read your entire thread on the subject a couple days ago. Found it helpful👍

Ok, a few more updates. I continue to work my way through the electrical connections in the engine bay.

I think I'll just describe my findings and questions via pictures...

Injector connectors are in bad shape. This one being the worst examples. I've got new EV1 connectors on the way. I plan on using all of the existing wiring and simply crimping on the new metal ends. Should end up with a cleaner finished product.

Drained the coolant. It was very green, like 100% coolant green without any dilution. Glad I drained it. Ran pure water as a flush as well.

This grounding wire is clearly non-original. Can anyone confirm if a 78 280z is supposed to have a grounding wire from the distributor base?

Pulled the ignition coil for testing. 2.0 ohms primary and 13.5K secondary. Based on the service manual, it should be about ~1.0 ohms primary and 8-12K secondary. This probably isn't the factory coil. I looked online for anything around ~1.0 ohm primary, but can't find anything. Most sites don't even list the resistance. Best I can seem to find is the flame thrower at 1.5 ohms. Any recommendations?

TBH, polishing up the connections is quite satisfying. Instant results.

A bit of sandpaper wrapped around a punch makes for a good setup to clean up the inside of female bullet connectors.

Thermostat housing sensors before and after. They weren't too bad to begin with, but I understand these are critical for the ignition system to work rightly, so I cleaned 'em up real nice.

Maaaaaaaybe more evidence of a true 70K mile engine? Thermostat housing has very little pitting and corrosion. My prior Z car was paper thin here.

Can anyone tell me what this little electrical device with red wire does that's screwed into the throttle body? I can't seem to make out the electrical diagram I have. Maybe it says "flood cut solenoid"? You can see in the pic mine has the ol' twist-em-together-and-call-it-good wiring method.

Anyways, more to come...

Edited July 23Jul 23 by kcpope

On the afm mounting plate. Black wire is factory connected directly to the afm mounting bolt. PO apparently thought the distributor needed a ground. Not factory. The red wire is connected to the bcc’d valve solenoid. NGK makes a 1.5 ohm coil. The label reads “Electronic ignition only”. Can be purchased from AMZ.