Captain Obvious

So any luck with a photo detailing just the linkage as it stands today?

Looks like a nice car, but I don't like it when people say stuff like this... Rug on the dashboard? Steering column clamshell off and sitting in the passenger seat? Aftermarket puffy armrest on the center console? and... Where are the flat-tops? 73 should have flat tops! For $12K? 100% original? I mean, I wish mine looked that nice, but... Original what?

I like that idea. That would remove the tangential component of the spring completely. Just like so many other throttle return springs. Mill some flats onto the actuator rod or drill a cross hole... Anything to get a grip on it. Attach some brackets to the rod to accept a hook on one end of the spring, and then hook the other end of the springs to the mounting points.

Here's another identify that wheel entry. What are these?

Haha! The "which is mine" part is a quote from the famous paleontologist, Anne Elk. IIRC, she did a lot of work with Brontosauruses. About the temp sensors... I did more, but figured that everyone here would gloss over and pass out so I didn't mention it. I wanted to determine what the temp sensor outputs would be at additional points, so I employed the Steinhart–Hart equation to model the thermistor outputs across the entire range. Using the data points in the factory service manuals, I now have a graph of the sensor outputs full range. It was during this process that the math highlighted some mistakes in the FI "bible" and the pre-78 factory service manuals: http://www.classiczcars.com/forums/fuel-injection-systems-s30/48782-water-temp-sensor-air-temp-sensor-resistance-charts-typos-manuals.html#post424758

Three mounting points on a shaft are often trouble. You have to do it right, or not do it at all. For those of us that aren't familiar with this system at all (like me)... Can you take a closer-upper pic of the linkage and it's mounts? Fill the long way of the frame with the linkage rod you currently have?

Great stuff. I wish I had seen that before I bought I bought the wrong engine... Might want to note that the later N47 heads are a little different than the earlier ones. I don't profess to know all of the changes, but one thing I can absolutely confirm is a threaded sensor hole into the water jacket back between spark plugs 5&6. And where does the W48 exhaust manifold fall in that progression?

The 58 Ohms makes perfect sense. Thats the resistance of the heating element in the thermotime. In fact, pretty much everything you have tested and posted makes sense with the exception of the grounding 45 thing, and the swapping the wires thing. One last thing before I throw in the towel and just revel in your success... Do the pins on your thermotime line up like the picture on EF-32 in the 78 manual?

Don't know if this is old news or not, but I've turned up a mistake in the pre-78 service manuals pertaining to the resistance readings from the air and water temperature sensors (Pages EF-52+53 for 1976 and Pages EF-53+54 for 1977). Similar mistakes are in the FI "Bible" as well. Apparently there was some difficulty translating from degreesC to degreesF. Add a language translation to that, as well as a positive to negative conversion complication, and you've got issues. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ To start, here's the 78 air temp sensor chart as a reference. The math works out as do the thermister resistances: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ But in the previous years, the temp vs resistance charts are wrong. Here's air temp: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ And here's the water temp sensor on the next page: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Similar mistakes in the Fuel Injection "Bible". Here's the air temp sensor test: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ And here's the water temp sensor test:

45 should be 12V to engine block when the key is in START and 0V to engine block at all other times. You should get these same readings regardless of whether the connector is clipped on the thermotime or not. And 46?... 46 is a little more complicated, but if you have the thermotime unplugged and the CSV connected, then you should see the exact same thing on 46 as you see on 45 - 12V at START and 0V at all other times. If you have both the thermotime and CSV unplugged at the same time, 46 should be always 0V regardless of key position. It makes no sense to me that it would work if you ground 45 and smoke if you ground 46... Are you sure you're not mirroring the numbers when you spin the connector around?

Haha! You must be in Marketing or Sales. :laugh: Seriously though... There's no way I would guarantee the performance of the ECU would be dead-nuts identical today as it was the day it left the plant almost forty years ago. No way. Things are better than vacuum tubes and oil filled paper caps, but we haven't figured out how to get all the long term drift out of everything yet.

Yeah, the vehicles voltage will mess with continuity and resistance measurements. You can not trust that tone to provide accurate results on anything that's powered. If you start adding voltage to a resistance or continuity measurement, seemingly unpredictable things can happen. So about that short to ground... Is this what made it work? Because I still can't explain it: Depending on the quality of the ignition switch and all the connectors between the battery and the thermotime connector, you may have gathered up enough resistance along the way such it wouldn't draw enough current to actually smoke, but there's no way putting a ground there as drawn should make the system work as intended. I'm an hour away....

Yeah, that mess is an indication of how well the anti-drainback feature is working. Here's a couple of my dissected filters. Old style AC Delco before they switched to the plastic filter support cage: (Notice the little split where the filter media was never connected properly at the factory.) Typical Purolator. Been this way for at least ten years:

And about that shorting to ground to get the CSV to spray with key in START... Is this where you connected to ground? Because if this is what you really did, then something should have smoked. If it didn't, I have no explanation other than someone has messed with the system somehow.

The CSV should be polarity and connection independent. I haven't taken one apart, but I expect it doesn't matter which connection goes to which prong. You could probably swap the two wires right there at the CSV and I don't think the system would care. The thermotime on the other hand is most definitely connection specific. I clipped the 1978 cold start stuff out of the wiring diagram and added a few notes: The connector pin on the tt which gets 12V on START should be 45 The connector pin on the tt which is connected to ground when the tt is cold should be 46. I'm not sure what you mean when you say "loss of ground at both 45 and 46". Without more specific measurement definitions... Are you measuring voltage, or resistance? The reason I ask is because you can measure 0V between two things, but that won't necessarily tell you if they are connected together or not.

Sounds like the CSV and the thermotime are both functional, but the rest of the stuff has me confused as well. I know you said it looks like all the original wiring, but maybe someone swapped something and then wrapped it back up again? Give me a little bit... I'm gonna make a picture.

Depends on the design of the oil passages and the position of the oil filter. I guess your truck likes the anti-drainback. On a different, but related note... I've had some filters that DO include that anti-drainback feature where the valve does not work. You can tell when you take the filter off the car that the inner portion has already drained out past the valve. It's not supposed to, but I've found that they sometimes do anyway. Maybe one in twenty?

"Oh, that's very different.... Never mind."

I had mine completely apart a few months ago, but I don't remember. I would assume it only goes together one way.

The ECU output stage uses open collector Darlington transistor drivers to pull the low side of the injectors toward ground in order to open them. That open collector style of driver is sometimes referred to as "floating" when it's OFF. Ummm... I'm assuming that has absolutely nothing to do with what you're talking about? If that's the case, then I've never heard of it. Give me just a little hint (PM if you don't want to influence the results from others) and I'll see if it rings any other bells?

My pleasure. And if all else fails and you're ready to throw in the towel, I'm about an hour south of you. Once you get over the cold start hump, I'm sure your car would make the drive.

Nothing jumps out at me as being out of the ordinary. I was half expecting to see the #1 wire on the rear side of the cap back by the carbs. I can't really explain how yours works fine with the small half moon to the rear when my car (and all the service manuals) say to put the small half moon to the front, but whatever works. Only other thought I have is that what you were thinking was TDC on #1 was actually TDC for #6. I remember you said that you pulled the valve cover to verify that you were, in fact, on TDC#1, so other than that, I got nuthin'. Anyway, like I said, whatever works. If it's running fine now, then I say don't mess with success, right? Unless someone else has a theory... Great pics by the way.

Yeah, a clear head is a requirement. Let us know what you find when you get back to it. But in the meantime, something to think about: You said CSV above, but I'm guessing you meant thermotime? You verified that the CSV is fine when you grounded 46 and it sprayed when you hit START. I'm thinking that the thermotime or a wiring issue may still be suspect, but I believe you have verified that the CSV good, right? The thermotime has two connections to it: One of them should go to +12 in START (just like one of the CSV connections). The other will be (depending on temperature) either a no connect, or a connection to the body of the thermotime. The body of the device is supposed to connect to ground through the thermostat housing. So, to answer your question... Yes, when the thermotime switches to ground, it grounds connection 46 through the mounting threads where it screws into the thermostat housing. It does not make a ground connection using another wire in the harness. It GROUNDS one of the wires in the harness.

:paranoid:

What an annoying, wretched, painful, dangerous, stressful pain in the arse. Sure glad that's over. Have you cleaned up the bore in the bottom of the strut knuckles yet so you can see what it's supposed to feel like? A little sandpaper wrapped around a gun swab chucked up in a drill does wonders.