Captain Obvious

Well put, and while it would be neat to mess around with it, I don't think I'm going to be pushing that limit that far. Haha!

From: https://www.nissanpartsdeal.com/parts/nissan-knocking-sensor~22060-w1502.html Part Fitment for 22060-W1502: Nissan 280ZX 1980-1983 L28ET Nissan Pulsar NX 1983-1985 E15T From Wikipedia: The L28 is a 2,753 cc (2.8 L; 168.0 cu in) 12-valve engine. Bore and stroke is 86 mm × 79 mm (3.39 in × 3.11 in) The E15 displaces 1.5 L (1,488 cc) from 76 mm × 82 mm (2.99 in × 3.23 in) So much for the 1800 / bore circumference. Haha!

Thanks guys for the part number info. I'll poke around some and see what I can learn. I always thought knock sensors were piezoelectric elements. Hit it with a voltage, and it changes shape. Hit it with a change in shape, and it produces a voltage. And yes, they often (always?) have a resonant frequency. Was never a topic of study by me, but I'll dig a little. 1800 divided by bore circumference seems too easy. Maybe that works for old Volvos? Harvest the igniter piezo out of my grill lighter and bolt it to the side of my engine and measure the voltage out? Or I could just not get greedy with the timing values.

Haha!! Sounds like a plan! I'd keep an eye out for weird behavior for a while too. I'm not really liking the timing of the failure of the VOLT bulb. Just too coincidental. Keep an eye on your voltmeter for a while.

Great! Glad to hear at least part of the problem was a simple fix. So are you "whole" now, or is the brake warning light still giving you troubles when you put the relay back in?

Thanks Zed. Do you have a part number for that knock sensor? I poked around and didn't find anything. And I remember that Whisper 2000 thing! Back in the dark ages, us guys the engineering department would sometimes pool some money and buy stuff that we thought were funny or scams. Perpetual motion machines, X-ray glasses... That sort of thing. For entertainment. The Whisper 2000 was one of the devices we purchased for our collection.

Yup. Moore's Law in action. Coupled with the rise in fuel prices and the desire to reduce emissions? I found a few references to knock sensors being added to cars which did not originally come with one. But they were vague and I didn't find anything that came to successful fruition. Granted, I didn't look very hard though. So the 280ZX had a knock sensor? Is that the turbo version? I don't think the NA had one.

Nice! I didn't even know they were available like that until I started poking around. I thought they were all built at "the factory". Glad to see they aren't. Adds credibility to the open source and community "heatkit" vibe. Good work.

Well that, and it's a shoe.

That operation with the relay removed is correct. There are three possible ways to light the warning lamp and they are "in parallel". If any of them connects to ground, the light comes on. By disconnecting that relay, you have simply removed one of the possible ways to connect the lamp to ground. The parking brake handle still works because it's still able to pull the lamp to ground even if one of the other paths (like the relay) have been completely removed. In fact, you said you have disconnected the brake fluid level switch as well, and the parking brake lever still lights the light. Same thing for the warning relay. Does that make sense? I'm trying to describe things for someone who doesn't do a lot of electrical work. Hope I'm not oversimplifying and or insulting...

@jonbill, Did you put the Speeduino together as a kit, or buy something turn-key? @AK260 I was looking through some of the speeduino and megasquirt documentation and saw they often use the MPX4250A sensor for MAP. Is that what you used? Nevermind... It's probably built into the 123 device. You didn't put it in.

Thanks Zed for the hook. I'm not "hands on familiar" with the 78 (I have a 77), but I'll do what I can. For 78, there are only a couple things that can turn on the brake light. 1) Pulling up on the emergency brake handle. 2) Low brake fluid level. 3) The brake check warning relay. As Zed Head mentioned, the third one (brake check relay) is tied into the alternator charging system and will light up the brake light if the alternator output drops too low. But it's SUPPOSED to go back out when/if the alternator output rises to normal again. So, I don't have any conclusive explanation for the latched warning light you experienced, but I would start with the easiest... If your brake fluid level is normal and your parking brake handle switch isn't "touchy", then I'd guess your brake warning relay may be having a problem. They fixed a lot of the electrical gremlins by the time they got to 78, but the earlier years have had issues with that relay.

I'm thinking that either someone added that to a car that didn't leave the factory with one, or the documentation is wrong and they put those on all the 78 cars regardless if they were 2+2 or coupe. Maybe they were offering that as an option in 78? Dealer installed?

Cool. My pic is from the 78 FSM:

According to the diagrams, that switch was used on the 2+2s. Present in 76, but not in 74. Don't know about 75.

Cool mod. What's old is new again. http://modelabasics.com/Ignition.htm

Thanks for the input guys. Zed, I've used my OBDII scanner on a number of newer vehicles and the timing numbers are way up there. Like fifty degrees BTDC. That's one of the reasons I started this whole discussion. I was wondering why a 2006 Hyundai can run that much advance, but our Datsuns top out at under thirty. jonbill, I heard the same thing about trying to use the vacuum signal from just one runner. I saw some pics of a "balance tube" sort of contraption to combat that. I don't remember if I saw that at Speeduino, or at Megasquirt (or jolt). In any event, I understand. Neat trick with the idle speed. I didn't know that was a thing. AK260, Yes, that helps. Thank you. So you're running a MAP sensor... But if you have it connected to the original stock source, it's a ported vacuum. Can the 123 deal with that? And what MAP sensor are you running? Oh, and I added fixed dwell to my device today. Seems to work as intended.

Nice. You sprung for the stick-on label? I never got back to you with other stuff... Sorry.

So speaking of vacuum advance and load sensing adjustments to the timing... Aren't some of you guys are running aftermarket ignition controllers or full engine management systems? Are you using TPS or MAP instead of vacuum? @AK260 , @jonbill , @Zed Head

As for the vacuum advance, I'm just messing around here on the bench with the distributor and I didn't want the vacuum advance to move at all. Problem was, my new bearing retainer worked so well that the two plates inside the distributor move so nice and easy now that they almost move all by themselves. For my screwing around, I actually didn't WANT them to move around, so I had two choices... I could either install the vacuum pot, or I could just lock everything together with a different plate and skip the vacuum pot all together. I chose the latter. Since I already had that disk cut as an earlier prototype for my bearing cage, all I had to do was drill a couple holes in it and use screws to clamp everything together. I think in the application on the car, having some sort of "engine load sensing timing adjustment" feature is desirable. The question is... Do you want to do it with a vacuum pot pulling on the distributor, or do you want to do it electronically using a manifold vacuum sensor or a throttle position sensor instead? The point made by John Mortonson in those thread from HybridZ is that you CAN do without vacuum advance completely. You'll lose some light pedal cruise gas mileage, but other than that, running with no vacuum advance at all doesn't really have much impact. The original system does it with the vacuum pot, but I'm just kinda poking around with doing it electronically instead. Re-inventing the ignition controller for the ten thousandth time again.

My laboratory really needs an upgrade. What I really need is big pole barn out-building. I've been told that would make everyone happier. My guess on why the originals were made out of plastic was because it was easier and cheaper to make thousands like that instead of machining them out of metal. There might be a little bit of "slippy" feature of making them out of plastic that would be beneficial as well, but I don't think it's that big of a deal. I just sized the holes a couple thousandths larger than the balls so they would be free to roll instead of binding in the holes. My thoughts on the matter... "They make the bearing cages inside ball bearings out of metal all the time. So why wouldn't it work here?" As far as a retaining feature for the balls... You can see in this pic that I'm holding the plate up off the bench and the balls are not falling through: I did this with tiny deformation marks on the other side of the plate. If you look closely, you can see two very small dots on either side of the ball hole. Those punch marks deform the plate and close down the hole a couple thousandths which keeps the balls from falling through: If I decide I'm going to use this distributor, I could install the balls and then put similar dots on the other side of the plate as well. That would retain the balls in the plate completely. But for all the messing around I'm doing right now, I just wanted to see if it worked. It makes assembly easier because I only need two hands to get in place instead of three. I'm so tired of finding those balls after I have dropped them!

So I was spinning the distributor on the bench again today and I decided I would put the rotor on it just to see what it looked like as it spun. Nothing really bad happened, but I did pick up a noticeable vibration at certain RPM's. I pulled the rotor off and balanced it on a thin piece of metal. It's not balanced around the center shaft. You can see from the balance point off center. That can't do good things for spark scatter, bearing longevity, or reluctor gap consistency: I'm guessing it's because of the metal having a higher density than the plastic portion: I also assume that the extra material on the opposite end is supposed to be a counterweight. I have no idea what brand rotor this is, but it looks like they needed to add even more:

For a fleeting moment I had the exact same thought. Almost even asked about it. But then I thought, "Chris would never do that." I should have let Captain Obvious go free! Haha!!

That's really funny! The bread making thing seems to be happening everywhere, including here. So far, we're pretty good at ciabatta (my favorite), and last night we took our third attempt at making tortillas. The ciabatta is third generation development and is now excellent and the tortillas need maybe one or two more notches up and will rival the best tortillas we've purchased at the store. I say "we", but it's the Royal We. I can only take credit for forming and cooking the tortillas. And of course, the role of quality control and product evaluation. The sourdough starter has been growing on the counter for about a week now? Hope it tastes better than it smells...

I also made a plate to lock the vacuum advance mechanism down hard so I could spin the distributor on the bench without worrying about the plates slipping around inside. There are several threads on HybridZ that talk about the advance mechanisms. Here's a couple links. John Mortonson seems to be a big champion of jettisoning the vacuum advance completely and bumping the static base advance up instead. He JB Welded the plates together completely: https://forums.hybridz.org/topic/21577-timing-an-l28-advance/ https://forums.hybridz.org/topic/49923-advancing-timing/ I didn't want to epoxy everything together, so I made this instead: Not ready for production, but works for locking my distributor together on the bench!