Captain Obvious

Wow Granny, that looks significantly worse than mine. Is that one pit on the vacuum port a rusted hole completely through? I wouldn't have paid for mine if I had seen it beforehand, and if I were to see yours beforehand, I might have thrown up right there on the counter in the parts store. Woof. So I put a couple miles on the car and it works. Doesn't hold vacuum for long after you shut off the motor, but I'm supposed to be headed to a car show this Saturday and it should get me there and back. I'll mess with taking my old one apart and swapping the seals into it some time after the pressure is off. Charles, I'm not sure the lathe will come in handy in building a device to take the clamshell apart, but the lathe will certainly be the perfect machine to reproduce one of these in stainless: Making a new one of those that won't rust and pit like the original is certainly on my list while I've got the patient on the table!

I was so frustrated by this booster that I didn't take photos of the entire process, but here are a couple. This is the front of the booster before I painted it. You can see the pitting. There is also a nice slip-joint pliers shaped dent at about 2:00 : Here's a pic of the snapped retainer loops. You can tell from how far those busted remains are twisted in towards the center that they wouldn't even fit past the dents in the other side of the shell. In other words... They bent those tabs in AFTER they put the two halves of the shell together. Because they certainly couldn't have gotten the two halves of the shell together in the first place with those retainers bent over like that. Nice to see thier blue "passed inspection" paint mark right next to the mangled metal: Here's a pic of the output shaft when I pulled it out. Their training manual says to "apply a small amount of silicone grease" to the seal before installing it: Charles, Next chance I get, I'm going to follow your lead and build some fixturing to take my old booster apart. Or crush it trying.

Ken, Car looks great! I'm "Mid-Atlantic" by some interpretations and I'd love to see the car, but not sure how far south you are. With the hood torsion rods assembled properly into the hinges, there should be no danger of anything springing apart. You put it together off the car and then once the assy is together off the car, you put it on as a unit and it should be uneventful. Also, is it my imagination, or are you going for "turn signal overload" in the front? Whee, have you got any pics of a gas shock mod? I've not seen that.

Let me count the ways. So I bought a rebuilt brake booster from RockAuto: A-1 CARDONE - 535104 (53-5104) - Power Brake Booster $84.79 + $25.00 core = $109.79 I open the box and it's unpainted bare metal, and the metal that is exposed is deeply pitted. This thing was apparently a boat anchory rusty mess that they bead blasted back to "shiny". It's clear that someone sent in their completely tired worn out old dead booster as a core. There are also clear signs of physical abuse. Almost all of the clamshell retainer catches are split open and the case is dented where the master cylinder mounts. I guess I should expect some of that... As long as the pits don't go all the way through and split catch tabs still allow the clamshell halves to seal, I should get over it, right? So I'm handling the unit and it feels slippery on the outside. Feels "silicone-ish"? I'm thinking I just clean it up and throw a quick coat of paint on it. I sprayed and cleaned and wiped and cleaned and sprayed and wiped... Then I sprayed a coat of rattle can black that instantly fish-eyed like I've never seen before. It's like a thousand guppies staring back at me. It's like someone dipped this thing in liquid teflon. Don't care anymore. It's mostly covered. Bolt it into the car and while putting the master cylinder back into place I notice that the output shaft looks shorter than my original boosted. Sure enough, the shaft on my original booster sticks out about a quarter of an inch longer than the rebuild. Try to adjust the shaft length and it's frozen solid. Won't budge. Whatever... So my pedal engagement location will be a little different. I'll re-learn the new position. Put the master cylinder in place and pull out of the garage. The pedal goes almost all the way to the floor before I get any braking action, and when I finally do get any action, there is no modulation. It's almost digital... Either coasting, or face through the windshield. No in-between. Now for those of you who have been through this before, you already know where this is going, but I've never been here before. So, I pry the seal retainer out and remove the (rusty pitted) output shaft. Lots and lots of silicone grease, but you guessed it... no reaction disk. Can't see it in there anywhere and can't feel it. So I take the whole thing back off the car and shake the crap out of it for a frustratingly long time until the reaction disk finally falls out the hole. Put the reaction disk back into place and put the booster back in the car. It works and will get me to my show this weekend, but I think I'm going to build some fixturing to take my old one apart. My old one is clean, un-dented, with the retaining clips intact. I think I'm going to investigate swapping over all the new rubber components from this rebuilt unit over to my old booster. Essentially paying $100 for a "rebuild kit" that I can apply to my original booster? Unpainted, greasy, dented, case with snapped retainers. Rusty components where rubber seals are supposed to seal. Internals not assembled properly. I hate rebuilt components... Starters, alternators, brake calipers, master cylinders, brake boosters. They all seem to be done by people who don't get paid enough to care what they're doing. Sheesh. Stark reminder of why I do my own work. Rant over.

Excellent. See? You had the power all along!

Yeah, I think that shred is what is left of the flap. What threw you off is that you were looking for vinyl, and that's not how they did it. And you know the only reason that your new cover (with the unused listing rod) looks the same as your passenger side is because your passenger side flap turned to dust as well! And you're right... 40 years is a long time for something like that. I'm surprised at how well the foam has held up!

In this pic... I think that brownish stuff hanging from the metal wire (known as a "listing wire" or "listing rod")? is what is left of your original flap. Most of it has turned to dust and it's hard to believe that it ever used to go all the way through the slot up to the seat cover, but I think that's the remains of the original flap.

Yeah, at quick glance, the NTE247 looks like a suitable replacement. Keep it as a backup?

Sheesh. No kidding! And what about busting school children? Busting school children is a terrible, terrible thing. I hear this is going on all over the country. Mean policemen arrest little children and put them in jail in the wrong neighborhoods do they can't even play with their little friends. Imagine... Busting school children.

It is absolutely possible that a component like that will test OK cold, but fail under load. I would highly doubt that type of failure to have occurred on both of them at the same time though. Could also have been a bad solder joint that you rejoined with the mechanical agitation. How long ago did you do the replacement and did you replace them with the same part number? Doesn't appear that they are made anymore, but I'm sure there are suitable alternatives today.

What is all this fuss I hear about the Supreme Court decision on a deaf penalty? It's terrible! Deaf people have enough problems as it is!

Forgot two things... First is that the 2N3055 is a single normal transistor and not a Darlington. That would be why it passed your Ohmmeter testing. Second, here's the datasheet for the 2SD412: http://datasheet.octopart.com/2SD412-NEC-datasheet-519873.pdf I wouldn't be surprised if the 2SD411 was similar in most ways to the 412. It's not uncommon for parts in a sequence to be very similar. The most common similarity I've seen is stuff like the collector to emitter rating. For example, the 412 is a max of 150 Volts collector to emitter, and the 411 might only be 100.

The output transistors used the ECU's are not your traditional NPN transistors. They are what are known as "Darlington transistors" or "Darlington pairs". The Darlington configuration combines two transistors together inside the same package, and the end result is a device with higher than normal gain in the same sized package. The circuit diagram for an NPN Darlington looks like this: Some Darlingtons also include internal resistors on the base connections of the transistors, and I believe that to be the case for the 2SD411's used in our ECUs. I dug a little on the web and didn't come up with a datasheet for the 2SD411, but I did find the 2SD412 which is also an NPN Darlington which includes base resistors. Here's a snippet from the 2SD412 datasheet that shows how the internal resistors are connected: Why is all this important? Because the inclusion of those internal resistors can throw off the simple Ohmmeter test of a transistor and give you strange readings. The bottom line is that I think your transistors were fine and the problem you were having was somewhere else. I think that the reverse biased E to B numbers you got were simply reading the voltage drop across those base resistors.

Yeah, I did a little digging before I got bored with the research. DIN 73379 seems to be a "family", and it all comes down to the "Type". I got tired of digging into it before I got to the bottom of exactly what "Type B" was. Some of the types are clearly suitable, but not sure about "B", The working pressure is certainly suitable, but I'm not sure about the permeability or longevity at temp. "Proof is left to the student"? Can I pull that?

The 70 to 72 carbs weren't SU's either. In fact, the carbs from every year was produced by Hitachi, not SU. So the 73-73 carbs are as much SU's as the previous years. Haha! And contrary to popular belief, I do not own a car with flat tops. That doesn't mean that I'm not still messing with them, but just not on MY car. In fact, if things go according to plan, there will be one more car running flat tops ADDED to the world in the not too distant future! Also different for the 260, Electronic ignition. Carbon canister. Speedo. Seat belt interlocks. Off the top of my head...

If I'm reading the numbers correctly, the hose in the picture is Cohline type 2122, and the catalog page can be found here: http://www.newcoproducts.com/cohline/catalog_page19.htm And on the catalog page, it says it conforms to DIN 73379 type B. If your still interested, research that standard online and see if it fits the application?

Glad you're at least out of the woods for now. but of course you know you can count on the fact that if it's an intermittent electrical connection somewhere, it WILL return again. But you can at least stay focused on electrical things and stop worrying about compression, manifold vacuum, fuel pressure, etc. Those kinds of things don't usually snap back and forth between fixed and not fixed. Sometimes, but not usually.

Thanks Chas. Glad to help. My 77 has been running great, but we has a couple days of colder weather and I was out driving in nighttime temps that were lower than anything the car has seen in a year maybe? In those colder temps the car still runs great, but I think it runs a little rich. With that in mind, I made that chart because I wanted to take a closer look at the readings from my temperature senders. I was thinking that maybe one of my senders (primarily the air temp) had drifted out of spec and was causing a little richer mixture. Good news? The resistances from my senders look fine. Bad news? The resistances from my senders look fine. It seems like the whole system is working as intended, and it was either designed that way, or maybe over the years there has been some "gain drift" on the enrichment contribution from the ATS. I know I'm chasing minutia and most owners would be more than satisfied with the current performance, but like you, I have to tinker. Can't help it.

I found my notes and here's what the output stage looks like: Note that I didn't have a Darlington symbol handy that included built in base resistors (and I didn't feel like creating one), so I left those two built-in resistors out. I can tell you, however, that the total resistance of the two of them is 2.7K Ohms total.

Maybe just a little above 300 Ohms at 175F. I'm seeing 325ish. Keep in mind though that there is a pretty wide tolerance band allowed for those sensors though. The FSM says it should be between 290 and 360 Ohms at 176F and the center of that range is 325. Essentially they're saying "325 Ohms +/- 11%".

Pins 11 and 26 internally connect to the open collector outputs of the two output transistors through 1.5K resistors. So you could put a scope on those two pins while the ECU is running instead of probing the injector connections directly. I believe them to be test connection outputs to check the operation of the ECU. You could also wire those pins to +12 and disconnect all the injectors and view the output signal as a clean square wave without any noise from the injector impedance. In other words... Instead of pulling the transistors up to +12 through the injectors, you can disconnect all the injectors and pull the transistor collectors to +12 through that 1.5K limiting resistor. Then you could scope the injector pins to see a clean square wave drive signal. Good for bench testing and may have been used for Datsun's ECU tester modules. About the white wires though. Interesting because I don't have any white wires with bullet connectors. In fact, my harness doesn't even have pins 11 and 26 populated. The ECU has pins there, but the corresponding harness positions are empty. I wonder if they put those white wires on the earlier 280's and then decided that things were reliable enough that they didn't need them anymore on the later years.

Here's a chart that I whipped up showing the resistance vs. temperature function for the temperature sensors for the 280Z EFI system. There are a couple values in the manuals at a few temperatures, but this fills in the gaps. Note that Bosch used the same sensor curve for both the air and water temp sensors, so this chart applies to both water and air: And for those of you who care about the theory, this chart was created using the Stienhart-Hart Equation with coefficients derived from data points in the manual. Stienhart-Hart: I did the chart in Degrees F because that's what I use, but if anyone wants this in Degrees C, let me know.

Haha! Thanks for the laugh! Pull the connector off the ECU and take some measurements. I'd start there. Well actually I'd start by wiggling the WTS, and AFM connectors... And for checking the sensor resistance measurements, I just posted a chart that should help: http://www.classiczcars.com/forums/topic/56146-280z-efi-temperature-sensor-vs-resistance-chart/

Dave, Focus my friend... Focus!