Captain Obvious

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!

Lumens, My claim is that once everything is tightened down properly, everything down there (on the strut side of the bushing elastics) all behaves as one solid member with no relative movement. In other words, there should be no relative motion between the strut housing, spindle pin, inner sleeves of the bushings, washers, or nuts. If your question is "Do I claim that to be true regardless if the lock pin is installed or not?", then I'll hedge my bets and say "I think it should be, but I'm not a mechanical engineer and have not done the detailed analysis." If your question is "Should I install the lock pin?", then my answer is "Absolutely. Why wouldn't you?"

I doubt that it's the ECU. Bad connection (at the ECU) on the water or air temp sensors or the AFM. I once had a very rich condition and after poking around a little, I realized that I had disconnected my AFM to take some readings and had forgotten to reconnect it. I was surprised the motor ran at all. But as for the ECU internals, the two output transistors drive in banks of three each and the bases of the output drivers are tied together so they both actuate at the same time. What else can I tell you..... The output transistors are NPN Darlingtons. That might explain any strange readings you got when testing them. I can't tell you the individual values for the built in resistors on the bases, but I did measure the total and write that down somewhere. I reverse engineered the output stage, but it's so simple that I have no doubt you would be able to do it yourself by the time I find my notes. I'll race ya!

And forgot to mention... That since the surface area is so small and the gap between the "plates" is relatively large, the end result is that the capacitance of said feedthru's is generally very small. That means they work great for high frequencies, but not so great on lower frequency stuff. The auction for the caps that I posted above are 1.5 picoFarads

Right of course! (Or is that left?) Here's a pic of a random feedthrough cap that I nabbed from ebay. They are commonly available as screw in, or press/solder in. I'm assuming what you have is not threaded. Here's a generic example:

Awesome pics Blue. Thanks much! Now get back to work on getting yourself a new website up and running. Charles, that's exactly the analogy I was going to use. An overgrown fuel sender friction ring. Namerow, I've got one on order from Rock Auto that should be here next Monday. I guess I'll wait until that one arrives before I try again to get mine apart. Guess I won't be driving my Z for a couple days...

Haha! I think this is a job that even I cannot accomplish simply with a lathe. Zed, I thought about applying pressure to disassemble, but I'm not sure it would make any difference. I was looking at that housing clamshell where it interfaces, and I'm not sure there is a lock. I think it might just be friction that keeps things together. I looked at it under magnification and I couldn't find any evidence of any lock or detent. I mean, mine is crusty and painted, but I couldn't find anything. Charles, Since you had yours apart and the interface points were easier to see, did you see evidence of a lock?

Charles, Thanks for the pics. After seeing that and hearing that it was still an effort to get that thing to turn even with that long of a moment arm, I'm skeptical that I'll be able to turn mine without rupturing a disk in my spine. Maybe rethinking if the educational value is worth the risk. I just hate not knowing though...

Once everything is tightened down properly, there is no rotation of the spindle pin desired or needed. All of the rotation needs to be confined to the bushing. And that goes for either stock rubber, or poly.

Sweaty, Thanks for the input. I went back and took a look at the pics from your rebuild thread. So in the pic above, is that the farthest you were able to get the booster apart? Were you able to get the black part in the lower right of your pic apart? The part you call the "piston"? Did you try, or was there no reason for you to go further than what you did?

If the spindle pin nuts are torqued down to spec, then that lock pin should see virtually no force in normal application. The inner cylinder of the control arm bushings should be pinched tight between the nut and the bottom of the strut casting and unable to rotate. And if that cylinder can't rotate because of friction to the knuckle, the lock shouldn't see any significant force. Also, the inner cylinders of the control arms should never be able to slide fore and aft inside the bottom of the strut assy. All those parts should be drawn in and locked tight together while driving. I'm no suspension guy, but I don't think that pin is deforming while driving. I've seen upset material along the edges of the spindle pins too, but I think it might be more due to tightening the control arm nuts and pulling the spindle pin hard to one side before tightening the other side. That or beating on the spindle pin in an attempt to remove it without taking the lock pin out first.