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Just a gut feeling, but based on the how-and-where-and-how-hard I tap on the ECU/connector, it seems like there might be a break in one of these coils...I think this only because they can rattle around a tiny bit in their respective tubes and would likely still "settle" with some sort of contact again because of the confines and 45+ years of work-hardening through vibration might do them in. I'll try and have a peek down the tubes with some sort of magification and see what I can. Alternatively, based on your comment about the darlington transistors, is this any sort of failure mode that makes sense for them? Where rattling or knocking with make them fail temporarily? The very temporary nature of the problem is what is most baffling to me.

Haha. Indeed. This is me, all day every day. No matter which way this goes, I will be using at least one of my ECUs as a learning/traning tool to do a refurb from the ground-up and truly learn every last function, and to really play with tuning. This is why I already had: A spare ECU, a spare AFM, the FSM, the FI Bible, Bosch Fuel Injection & Engine Management, an Ignition 1-2-3 distributor, and an oscilloscope...as well as a host of articles and posts from around the Internet. But I had planned to do this on my own schedule. It seems my Z has other ideas... In related news, last night I discovered that rebuilt ECUs are actually a dime a dozen; I just failed to Internet properly. I've fallen into some sort of pavlovian response mechanism where I assume everything is unobtainium and start scouring ebay and specialty z-parts shops. But if you look at AutoZone, O'Reilly, RockAuto, NapaAuto, etc. a rebuilt unit can be had for as little as $200, or $175 if you are willing to return a core. I've now re-added the standard parts-jobbers for future needs. It looks like they still have some bits and bobs. If it is useless I can return it no problem, so I figured: why not? When it gets here I'll do some compare-and-contrast. More news at six. Film at eleven.

Ball joint failure is a real thing. It usually causes major damage and loss of control. So the calculation is about how close a person wants to get to that catastrophe. Which also endangers other people on the road. But in this case, Nissan has given an inspection procedure. If it meets spec. why replace? What's odd is that they say that the ball joint cannot be disassembled, when, obviously, it can be.

This is a spread sheet of what I had couple of years ago when I tried to sell on Facebook. Not many left the building…..

I have an embarrassment of riches when it comes to standard A11 600 000 ECU’s for 280’s. Can’t ever see using them all locally, so anyone interested in picking up a “Few” in the USA where you can distribute them from there to those that need? Asking $50 each. Ask me for volume discounts….. There are a few ZX turbo, both 280 and 300 if that suites your fancy. I can try to build a list. Similar situation with AFM’s…..

Sometimes I take a best guess, no matter what the depth of my knowledge on a subject, and just try something. Then hope my brain will take the results and come up with something better. In retrospect, I doubt that the transistor(s) was/were the cause of the problem. I imagine that almost any open circuit or short inside the ECU could cause it to malfunction. Your situation is unusual in that it seems so repeatable that it's almost controllable and is the same for two different ECU's. Maybe you're just losing a connection at one of the pins. Probably one of the multi-vibrator functions! 🥴

@Captain Obvious I'm always on the lookout for NOS OEM parts, sometimes they have the right part number but are not in Nissan boxes...you just have to know where to look. I have a spreadsheet with all the period correct cross reference numbers and keep a look out for those on a regular basis. It seems the Nissan part suppliers of the day back in the early 1970s had no qualms about selling the same part to Lazorlite/WorldParts/BeckArnley. I wont try and reproduce the coating, too many other parts to restore at the moment but will keep it in mind for the future. I will use the master cylinders with the cast in letters on my 8/70 and 10/70 240Z, the engraved one will go on the 5/70 for period correctness. The fun anomaly I have discovered in the wire clamps. Some people say they should be all clear zinc, other say gold zinc...what's correct. Again referring back to the Green BAT 5/70 240Z, it has gold zinc wire with clear zinc screws...go figure that one out as it's totally original. However the large ones on the radiator hose are clear zinc.

Wow. I wish I could nap a set of pistons/seals/springs/washers for $85. If you see another one of those, please send me a quick note to let me know? Nobody will see the pistons after they are installed, so it's not like you're going to be judged on whether that coating exists or not. And I understand about polishing it off... The decision which is better...Keep some of the original failed coating, or just remove it all. Totally understand. If you do decide to look into it, there is probably nothing very special about that coating, It's a black oxide coating on steel. It's a controlled rusting kind of coating. Similar to "gun blue". Any coating shop should be able to reproduce it, but cost prohibitive for a single piece. As for the changeover point between the stamped lettering and the cast-in lettering? In that other thread it appears that point is between 7/70 and 12/70 when they changed the markings from stamped-in to cast-in. I got the chance to mess with a 9/70 car and it had the cast in lettering. So with a sample size of one, I could narrow the date window down to between 7/70 and 9/70. However: 1) It's a sample size of one. 2) I don't know if it was the original brake master on the 9/70 car, and... 3) The 9/70 car was an automatic, and some of the stuff on the autos is different than the manuals from the same month (valve cover for example). All that said, I think your MAY car should have the stamped lettering.

The large cans bolted to the outside of the chassis.... Labeled NEC D411A... Those are discrete transistors, but are a unique pair in the design. Those are the final output transistors that drive the injectors. There are only two of them, and they are known as "Darlington Transistors" because of the internal construction. The discrete transistors I was talking about are the much smaller black plastic bodied things with three legs. I whipped this up labeling some of the components: And you had asked about the copper tower and blue things near the connector... The copper towers are coils (aka inductors or chokes) and the blue Chicklet things are capacitors. Those two components in conjunction act as a filter on the incoming signals to the ECU in an attempt to eliminate high frequency noise. They originally designed the ECU with provisions to put those filters on many of the signals going to/from the main connector, but it appears they decided somewhere along the way that they are not all necessary. So they only populated a couple of them by the time they got to the end of the run. Most of them are just shorted across with a piece of wire. Hope that helps.

It's just the law overhere... i can't help it..

@Captain Obvious I've been buying them up from Ebay, they pop up every now and then. Last kit was in Feb this year, I got the pistons/seals/springs/washers for $85! Yes the piston did have the black coating, it was already coming off when I stripped the cylinder down. I hit them with the brass wire wheel to clean them up. I'm not sure the original coating from 50 years ago is still available so I'll keep them as it is. Hopefully nobody faults me for this. Nothing wrong with pedantic, you guys have been doing this longer than me and are more knowledgeable. Thanks for pointing it out. I have a rebuilt cylinder with the early engraving, I'll make sure I use that now I know it's the correct one. I have two of the cast type so I'll keep those for the later August 1970 and October 1970 240Z I have. Anyone know the exact changeover date? I'm using the Green May 1970 240Z that went for $310k on BAT as my reference along with @Zspert for his intimate knowledge with the cars. Again appreciate you correcting me and guiding me to the correct parts for my restoration.

Seiko Watch CorporationThe Datsun 240Z and Prospex Speedtimer: New collaboration...

I'm just learning what's what. I have near-zero electrictronics background but I am handy with a soldering iron and recently bought an oscilloscope to learn on (Tektronix TDS 1012) I can see that the WMIC labled parts are all metalized polymer capacitors and the resistors I recognize are pretty common...but the ICs? Are those the silver 14(?) pin guys with the heat sinks? And what the heck are those copper-coil towers with blue things next to the plug? I need a magnifying glass. I can't read 'em. Nothing looks like a discrete transistor that I recognize, but the round caps on the side say NEC...so I guess that would be those? When I was running the car previously I've grabbed the harness connector and given it a good hearty wiggle with no change but today when I did the second "tap" it was on the plug and not the unit itself, and it went off like a switch. Mostly though, when I tap it with my foot it is on the lower metal bracket. Tomorrow I will be sure to try and move/wiggle each bit of the harness from the connector up on into the dash and see if that makes any changes.

Most of the components in the ECU would be available generically. Caps, resistors, discrete transistors... No problem. The integrated circuits, however... Nada. You should be able to get pretty much anything but the ICs at Arrow and Mouser. But before you condemn the ECU, I would suggest try to isolate the problem. Even if it's an electro-mechanical issue, it would be important to know if the problem is in the wiring or connector to the ECU, or inside the ECU itself. So, the first thing I would try, would be to slowly and gently wiggle the wiring harness to the ECU and see what happens.

Roo, Nice work on the brake stuff. I have a couple comments / questions about the master cylinder: First, where did you find the rubber seals you used to rebuild the master? Second, the pistons originally had a black oxide coating presumably for friction reduction and/or corrosion protection. It looks like you hit the pistons with a wire wheel and burnished that coating off? Any thoughts about having them recoated? And last, a little pedantic, but I'm thinking that is not quite the correct master cylinder for a 5/70 car. I'm no expert on the early cars, but I think you should have the one with the ground and stamped "F" and "R", not the cast-in markings. The correct one I believe would look like this: There was some discussion about such matters here >> https://www.classiczcars.com/forums/topic/65579-brake-master-cylinder-46010-e4602-up-to-91971/?&page=3

Hey All, I hope someone can help me out, this is a rehash from another Z forum, but I'm spreading it in the hope of finding a solution. I'm in the early stages of restoring a 71 240z and thought a chassis jog would make life easier. As of now, step one is creating headaches, as described below. As of now i have built a chassis jig/frame and am in the process of bolting up my bent 240z to it. And here is the rub. I spent countless hours pouring over the only chassis dimensions document out there. That being the BF-3 204z dimensions PDF. As described previously I was thinking that the dimensions are wrong, or my car is very, very bent. With what I describe below, I don't think the car can possibly be 'that' bent. Some framing of the problem, with a crap pun: I have used four mounting points (described from rear to front): (1) Rear diff mount (not mustachio bar), (4 lateral bolts) (2) Front mount to the rear lower control arm, (4 lateral bolts) (3) Transmission mount, and then (two lateral bolts) (4) Front Strut Tower Top ("A" point). The dimensions (that don't work): (1) Reference point. (2) 465mm from ref. (1). this one is 15mm to short. (closer to 480mm) (3) 1427.5mm from ref. (1). This one lines up. (4) 2381.3mm from ref. (1). This one is 20mm to short. (closer to 2401.3mm) To my point......what the heck is going on here??!! Between point ref 1 and 2 my car is 480mm. In the BF-3 document, there is no reference to a 480mm dimension.... The car cannot be warped by 15mm, it's all structural mounting points. So, what am I missing? Moving on to the dimension between 1 and 4. Again, too short by 15 to 20mm... So, what is the actual dimension? All of the lateral dimensions are correct. I scratch my head. It's great though as it gives me something to talk with my wife about over dinner. Thank you in advance!

I'd love to have quick jacks, but I've used a set of standard plastic ramps for a couple of decades.

I've used common jackstands for years. )n the 280ZX in both front and rear there are obvious places which can support jackstands. In the rear, I slide a floor jack under the differential, lift on it and place jackstands under the places in front of the axle where the suspension bolts to the underbody. it's not hard to find stout places that can support the stands. What the factory manual says aren't the only places you can support the car if you're thoughtful about it. In front on my 280ZX, I slide the floor jack under the cross beam beneath the engine, then position the jackstands under the stoutest place in the frame rails with a chunk of 2x4 on top of each jackstand to spread the weight out. On my 280ZX I jack up the front first, then the back. It's low enough that getting much of an angle on either end makes it hard to access the other end. you may have to slide the jack in from the side, not the front or back. Lift carefully. Push on the car and make sure it's stable. Push on it after the jackstands are in place, and double-confirm that it's stable. Patience and thought will yield a safe result.

These units are primarily “pth” assembly. They have aged with time IMHO have passed there designed life span. There isn’t as far as my knowledge a test bench that will run it through post diagnostics. My suggestion would be to search this forum and find someone that doesn’t have any use for the spares they have accumulated over the years. Mine are gone to other folks in the same predicament.

PNG versions

I took a bunch of photos of the ECU for inspection and parts hunting

Hi all. Longtime listener. First-Time caller. My question to to community, in short: If you have a rock-solid 280z with the stock EFI, what happens if you "Tap Control Unit" while running? Anything? What if you knock it "a bit harder"? I have a '78 280z that will very random-ish-ly very occasional-ish-ly simply turn off as though I had removed the key. After 10-20 mins of sitting, it fires right up and runs like a train...until it randomly turns off again, leaving me in some scary circumstances. Sometimes it fires up immediately like nothing happened. I have been trying to diagnose the issue for quite a while. After the last episode, I've decided she's never leaving the garage again until this is sorted. While testing in the garage I randomly closed the car door and it immediately shut off. I thought it was a coincidence. Later, when I opened the door, it shut off...but then started immediately. I found a couple posts online of similar examples: https://old.reddit.com/r/Datsun/comments/1f38p25/280z_shut_the_door_car_shuts_off_bad_ecu/ https://old.reddit.com/r/Datsun/comments/1iu2huj/280z_random_stalling_issue/ I have since checked every ground, pulled the drop resistors, cleaned/de-oxed all the connections and made sure they were tight. Just for good measure I swapped-in my spare ECU. I thought that had fixed it...I've been running it for an hour-per-lunch for the past 4 days, opening and slamming the door every 5mins, without issue. I was beginning to think I was good, until today. After about 20 mins of running I opened/closed the door and...stumble stumble stumble...running on 3 cyls...stumble. I gave the ECU a kick, and Poof. Back to normal. Kicked it again...sumble stumble...kick again...stumble...OFF. Won't start. Wait 10 mins. Starts immediately, runs like a train. In the reference book "ELECTRONIC Fuel Injection - 280Z Electronic Fuel Injection Theory Troubleshooting" on page 39 it also has a small reference under "Engine Misfires - HC Reading Too High" it says "5. Tap Control Unit While Driving To See If This Aggravates Or Alleviates The Problem. If So, Try Another ECU." So...have both my ECUs aged-out and need rebuilt? Or is "kicking the ECU" always going to result in some stumbling while 'something' re-sorts itself, even on a "known-good" ECU? I found a thread of a similar-but-different issue where a fix was successful: https://www.zcar.com/threads/efi-harness-continuity-voltage-problem.311536/page-2 And a quick-comment-on-the side by @zedhead that "In my case, I replaced the transistors and that fixed it. " (shot him a DM) My follow-along questions would be about rebuilding and where to get parts...Trying to find a rebuilt unit seems like a non-starter. I spoke to David at MSA today about timelines, because "The rebuilder is locating a qualified Bosch-experienced technician"...for about 3 years now. I'd be entirely happy to rebuild it myself and document the process...but I have no idea where to find components. Arrow and Mouser came up empty. Someone mentioned I should ping @Captain Obvious, which is what brought me here. Would love to hear everyone's thoughts.

An original early brake master cylinder was also sourced for the restoration. The ultrasonic cleaned it up nicely and I've disassembled it and replaced all the seals with original Nissan/Tokico parts. I just need to bleach the plastic reservoirs so they are nice and white. It should look like this once complete.

Continuing on from rebuilding all the original suspension components, brakes are next in line. Fortunately my May 1970 240Z came with the early brake rotors. I have derusted them, machined to tolerances and painted them to original spec. The hubs are cleaned and painted and I have NOS OEM bearings for them. A set of original Nissan brake pads have also been sourced. The brake calipers are the correct date coded set for 1970. I have degreased them in the ultrasonic, cleaned off all the corrosion using a acid solution. A light sandblasting and high temp satin clear finish give them the factory new look. A NOS OEM Nissan caliper seal kit is used to finish the build. All bolts and fittings are re-zinc plated. My goal is to use all original/OEM parts in my restoration.

What a load of rubbish, there's no way the ball can wear out that much! The Japanese engineers that designed that part knew enough about metallurgy to design the part so that never happens. The cheap stuff now coming out of some countries may be a different case, but not the originals.