FastWoman

I'm just thinking out loud: I had a notion for how to build an interesting linear circuit, with a possible application towards replacing our crumbling ECUs. We'd have off-the-shelf parts and open-source design! I don't know whether I'd want to get into a project like this, but I'm thinking about it. Sure, it wouldn't have the coolness and sophistication of a digital design, but then again, isn't there a certain coolness about maintaining analog control? My thought is this: It should be possible to take two voltages and generate an output pulse whose width is a scaled product of those two voltages. This schema would use a typical voltage ramp (timing capacitor) with a threshold trigger. One voltage, transformed/scaled from the AFM output, would create the threshold. The other would essentially set the mixture, as a weighted average of some base amount, with compensations built in for other factors, such as CTS, ATS, TPS, etc. (now including an O2 sensor! woohoo!). This "mixture" voltage would set the rate of the ramp. What would make this circuit unusual is that the mixture voltage would be summated with the ramp voltage to create a charging voltage (i.e. that feeds the timing capacitor via a fixed resistor), so that the current feeding the timing capacitor is scaled in proportion with the mixture voltage. Designed this way, the ramp would be linear, rather than exponential (approaching an asymptote of the charging voltage). This strategy would depart from Bosch's incremental compensations and would adjust mixture uniformly at all rates of airflow. To me that makes more sense. So I'm thinking this thing really shouldn't be all that hard to create. The hard part would be reverse-engineering the weighting of the various compensations to the "base pulse." Again, I'm just thinking out loud and putting my thoughts down here as a note to myself in the future. Not enough time right now to sketch out a circuit. Does anyone else have these sorts of troubled thoughts?

Jai, you can get all the crimp connectors you need from your local auto parts store at such time as you are ready to do that work. There is no need to order from Hong Kong. It's pretty common stuff. So let's wait on that too! In my estimation, there will not be anything your car needs that you can't get within 5 business days, and most everything can be gotten within a day or two, free of shipping.

^^^ What Steve and Chas said! I assume your car will start, but just not continue running indefinitely. Whenever you finish doing something, like replacing your ignition wires, confirm the operational state of the engine: Make sure it starts and runs. Replacing plugs, wires, cap, rotor, and fuel filter shouldn't get you in trouble, as long as you are very careful to replicate the plug wire connections EXACTLY. (You can't mix the plug wires up, and the numbers banded onto the wires should help with that.)

Photograph requests: Could you get a good, sharp, close-up photo of the sensors and connectors in the front of your thermostat housing, just below where the upper radiator hose connects to the engine? And could you also get a close-up photo of one of the electrical connectors on an injector? I want to see the condition of the connectors.

But.... having said everything above... none of this is the source of your problem right now. We need to diagnose what the problem is -- FIRST PRIORITY. So let's focus on that! I would try to replicate the problem in your driveway, so that when the engine dies, you can diagnose it right there. You will have the tools, and you won't need to push your car to a safe place. Do this: Buy the can of starter fluid. Find an orifice in the intake manifold where you can spray the stuff in. If the can of starter fluid comes with a little tube (or if you can borrow a tube from a WD-40 can), you can spray the stuff right into a little vacuum fitting. There should be a little vacuum hose going from a nipple on the intake manifold to the fuel pressure regulator on the fuel rail. Pull that tube off of the intake manifold nipple, and see if you can fit the starter fluid tube inside it, so that you can squirt the fluid right inside the manifold. If so, then good. Now replace the vacuum line. Next, start your engine, and let it run in the driveway until it hopefully dies. Then move quickly. Shut off the ignition, pull the vacuum tube, spray fluid into the intake manifold for 1 or 2 seconds, replace the vacuum tube, and then try starting the engine. If the engine runs for a few seconds and then dies, then you've ruled out the ignition system. Just to be conservative, wait about the same amount of time it took you to spray the starter fluid into the manifold, and try starting again. It probably won't start. Then give it another shot of starter fluid and try again. If it runs a few seconds and dies, then you've pretty much nailed it. It would be a fuel problem. If, on the other hand, the engine doesn't start with the first shot of starter fluid, you probably have an ignition problem. Figure out which -- fuel or ignition -- and we can continue diagnosing from there.

Misc thoughts/answers: 1. Before ordering anything, try buying locally. That will save you $$$ on shipping. You could have bought the same K&N oil filter at your local auto parts store for 13.99 (AutoZone price) and saved the $5 shipping (although you would have probably had to pay about 70c in tax). 2. I would set in to replace all the items in your tune-up kit. It's an easy and quick job. When replacing the distributor cap and wires, note that the wires are numbered (or should be, as I recall). Set the new cap beside the old cap (without disconnecting anything yet), and plug in the new wires to the new cap in the same order as you see on the current cap. (You should pick up a can of silicone dielectric grease, which will become your best friend for making electrical connections, and lightly grease both the metal contacts and the wire boots before you plug them in to the cap.) Now double-check the order of your wires. Remember that the #1 cylinder is at the front of the engine,and the #6 is at the rear. Finally, un-clip your old distributor cap, pull off the rotor (pull straight up), push on the new rotor, and clip on the new cap. Pull and replace your spark plugs ONLY WHEN THE ENGINE IS COOL. You will need a little spark plug gapping gauge to bend the electrodes to the correct gap. Get that tool at the auto parts store. It probably costs a buck or so. Also buy your spark plug socket there. (Take a plug with you to make sure you have the right size.) When you pull your plugs, keep them in order from #1 to #6, and photograph them for us. It is important that we see the bottom (dirty) ends of the plugs. The other end doesn't matter. Tighten the new plugs to 11-14 ft-lb of torque. For you, if you're using a typical 3/8" ratchet handle, you would pull on the handle with about 15-20 lb of force. Pretend you're lifting a turkey. Before snapping the new boots over the new plugs, lightly grease both the contacts and the boots with dielectric grease. 3. Replacing the fuel filter: When you pull off the first hose, hold a rag around it to catch any spraying fuel. There won't be much, but you certainly don't want to get sprayed in the face! Be careful when you remove the old filter to dump out the fuel onto a piece of white paper. Photograph it for us. 4. Go ahead and change your oil and filter any time you are ready. 5. Hold off on replacing electrical connectors until we get your car running again. You've purchased a very nice set of connectors (that I wish I had on my own car), and you will be able to make good use of them. But let's wait on that. And in answer to your question, I believe your heat gun would be just the right tool for the heat shrink. You couldn't ask for a better tool. 6. Your engine photo: This does help a bit. I see more detail on that large red hose. You said it looks like a garden hose, and I would agree. Therefore, you need to replace it eventually. But it's not a priority right now. Vacuum leaks are a higher priority. Identify the small vacuum hoses (pretty much any hose connecting to the intake manifold), and see if any of them are brittle or cracked. If they are, replace them. Ask the folks at your auto parts store to look at your engine and sell you the replacement hoses you need. Replacing them is easy. Do it one hose at a time, so that you don't forget how everything was hooked up.

Mr. K is smiling right now! "Love cars, love people, and love life." I've owned quite a few sports cars in my life and have belonged to several classic car communities. I've got to say there is more good karma on this list, in this community, and surrounding this car, than I've seen anywhere else. Thanks for helping Jai out, guys! And Jai, "Enjoy the ride."

Jai, most manufacturers start manufacturing the next year's model towards the end of the year. How wonderful if you can get a printed manual for the '76 gratis! There are some great people on this list! I agree that the EFI of the 280Z is worth keeping. There shouldn't be *too* much work to do on that system to make it solid, provided the manifolds are mounted/sealed up solidly. The proceeds from the sale of the 240 should keep your 280 on the road for a long time. To me it sounds like a prudent plan to sell the 240 to support the 280. And as you say, you will be doing the right thing for the car itself. I totally "get" your moving Redwing's shifter knob and steering wheel to the 280. Those are very personal items, and they should stay with you.

Just another factor in the equation: Apparently Redwing is a one-owner Series 1 that Jai would have bought when she was in her mid 20's. She had to go on the dealer's waiting list to take delivery of her new supercar. And her dad (now deceased) taught her how to maintain the car! If that doesn't spell sentimental value, I don't know what does. Sadly, Jai doesn't have the resources to restore Redwing the way she should be restored. But maybe somebody local could do some bartering. Maybe there could be some sort of dual ownership thing worked out, so that Jai doesn't have full, unencumbered ownership of the car, but still gets to drive her in rough, but running condition for as long as she continues to drive. Maybe this could be a restoration project for someone after Jai is finished with her. Win-win. And I'm sure Jai would want the car to pass to someone who would restore her to her full, former glory. I'm just thinking out loud here. Redwing is quite rough, but her pedigree is solid.

I did the relay modification in my '78 entirely in the relay box area (passenger inner fender), using a strategy essentially the same as that linked by Tamo. I was rewiring my main fusible link wires (removing all of the weird OEM junk) and also upgrading my alternator wire. So while I was there, I simply snipped the four headlight wires, branched off to the relay housing, and added my two relays. Since I was installing maxifuses in this project, I simply designated another maxifuse to feed the relays. If I ever needed to go back to OEM, all I'd have to do is to reconnect the 4 wires I snipped. With this implementation, current path is very short, and nothing needs to pass through the firewall.

Hi everyone, Jai (Redwing) is a bit timid about protocols, even though we're a pretty informal bunch. So I'm taking the liberty of explaining her situation. She needs a bit of special help from the Z community, starting with a frank assessment of her situation and the formulation of a plan of attack. She's going to need a lot of parts help from us, but I think she is absolutely worth all the help we give her. Think, "What would Mr. K do?" We've all already met Jai. She's 72 years old, lives in Georgia, and has been a die-hard Z'aholic from an early age. What most of us probably don't know is that she lives on Social Security, and her finances are very, very tight. As she puts it, she's got about $200 per month to spend on groceries, flea meds for her dog, gasoline, and "whatnot," after paying for all the "have to" items. And from this budget, she needs to maintain her '76 Z, which she has named Red Bird. Red Bird seems to be a pretty solid car, but she's got a problem right now that we're trying to figure out. When Jai gets her next Social Security check, she will be able to buy a Factory Service Manual, which will help her enormously. She cannot deal with an online FSM, because she's working from a tablet. Once she is able to study the FSM, she should know much better what we're talking about. The FSM has all sorts of great explanations about how these vehicles work. Hopefully Red Bird has a simple little problem. I'm guessing it's a fuel pump, but considering Jai's tight budget, the time honored approach of replacing stuff that MIGHT be wrong would not be wise. We need a solid diagnosis, so that Jai doesn't waste her parts money. I had suggested to Jai that it might be a bit too ambitious to maintain Red Bird with her tight finances, and that she might be better off with cheap transportation (an old beater car) and some cash to put into her first love, her 240Z, which she named Redwing. It will take quite a bit of work to get Redwing roadworthy. Jai had initially explored this possibility and was told it would cost $13,000 to $15,000 to restore the car. But what I explained to Jai is that you don't have to completely restore the car to enjoy it. You simply have to get her back on the road and perhaps spray her with some cheap paint for a bit of color and shine. Sure, Redwing will be sort of rough, but she's a proud old girl with 250k miles of history with her owner! No fancy paint job can measure up to that! I think Jai liked this idea, but she can't bear to part with the 280Z (Red Bird). So the plan is to get Red Bird running and use that car for transportation, while picking away slowly at the 240 to get her back on the road. Then when Redwing is roadworthy, Jai can sell Red Bird and recoup her investment. (She is only allowed one vehicle on the road in order to qualify for Medicaid.) The sale of Red Bird will then give her operating funds to maintain Redwing and have some reserve for little surprises (automotive or otherwise). I had also suggested a trade-down to a red first generation Miata (cheaper, decades younger, and probably more reliable), and she's not opposed to that, but she wants to try to make her Plan A work -- to hang on to the lovely 280Z (Red Bird) while getting the 240Z (Redwing) back on the road. And hey, why not? Can we help her to do this? Her 240 is not too rusty, has a dent or two, looks like hell, and was parked 8 years ago when it needed brake work. I suggested this might be what is required to get the 240 back on the road: Engine: Probably OK. Needs to be brought back into service gently. You can put a big wrench on the crank pulley nut and try turning the crank. If it turns (isn’t frozen/rusted), then you’re probably in good shape. Fluids: all need to be flushed and changed. ($100) Carburetors: probably need a minor rebuild, just to clean them out. Maybe $50 in parts. Fuel pump: might or might not work. However, a fuel pump for a carbureted car is a WHOLE lot cheaper than one for a fuel injection system. Brakes: I’m guessing they need a complete overhaul – maybe $600-700 in parts, plus your labor if you feel you’re up to it. Clutch master and cylinder might need rebuilding (or might not). Maybe $200? Gas tank: Needs inspection. Maybe needs cleaning and coating inside. Tires: need replacement ($600) New ignition parts ($100) Chasing electrical gremlins ($100 in misc parts and a bit of patience on your end) Water pump (seal might leak) $20 Coolant hoses (likely rotted) $25 Belts $25 That all adds up to $1920. I suggested this budget with the idea of having operating funds. But it can be done cheaper. For instance, Jai could rebuild some of the brake parts, rather than buying them rebuilt. Maybe the ignition is good as is -- or maybe just a new set of cables and plugs. I wonder just how cheaply Jai can get her 240 running and back on the road (safely, of course)? I'm thinking some of us might have a few parts sitting around that we could offer as needed. She could really use them. Then after Redwing is back on the road and the investment in the 280 has been recouped, perhaps some minor beautification would be in order -- a $500 paint job and a couple of new seats. Anyway, I've started this thread to facilitate our brainstorming with Jai. Can we help Jai to realize her dream of getting her Redwing back on the road -- on an extraordinarily slim budget?

The grease on your vacuum selector valve might be all dried up. You can rebuild the thing (moderately easy) Here's how I did mine: http://www.classiczcars.com/topic/32856-refurbishing-the-hvac-vacuum-selector-valve-in-a-1978-280z-useful-info/ You also need to check all the vacuum tubes to see that they're still connected and not cracked. You can easily access everything without yoga pants if you remove the center console.

The '77 and '76 have a few differences. Probably 95% of the car is exactly the same, but that leaves 5% that isn't. It's far better to get the exact year. FAIW, my '78 had a leak in the AC when I bought it. The problem was the loose low-side flare fitting on the firewall, which was covered with leaked compressor oil. I tightened the fitting, and the AC has held its charge for years now. So it can be a very simple thing -- or not.

Jai, to be clear, when i say you might have a fuel problem, I'm not just talking about fuel pressure. I'm talking about everything from the fuel tank to the fine spray coming out the injectors. There are many ways in which "fuel" can screw up. We'll see what the starter fluid tells us!

^^^ Everything that Chas said! If you were to look at my Saturn, you would find the same thing: The wire to the clutch on my AC compressor is disconnected. Why? It's because my compressor went bad, and I couldn't seem to get other people to stop trying to turn the AC on. Unplugging it was a simple solution. Not knowing anything more about your AC than it being disconnected and sitting, I'd suspect it will cost a pretty penny to bring it back. I'd say you first see whether it has pressure in it by poking the stem of a Schrader valve (like on your tires, except on the lines near your compressor). If you've got freon, that's good news. Next question is whether your compressor pumps the freon. You would try reconnecting that wire -- or better, just sending +12V to the compressor clutch. Does the compressor run quietly? Can you feel the lines changing temperature? If so, then good. If you've got cold air, all the better. But I bet you won't. if you have some freon and the compressor pumps at all, then you might take the system to a qualified auto AC technician. He'll have to figure out what's already in the system, what it needs, etc. It will probably need evacuating and recharging. You can find R12, BTW. It's a bit expensive, but it's available on sources such as ebay. I remember it being maybe $30 a pound, and you will need a couple of pounds. But chances are your system doesn't hold pressure (all the freon gone) because of a bad seal (compressor needs rebuilding), or even more likely the compressor has bit the dust and won't pump. That would be an expensive thing to fix/replace. I've retrofitted a couple of R12 AC systems with R138a. I don't think I would do another one. Results were fair at best, and the R12 compressors don't hold up very well under the higher pressures. (My failed Saturn AC is a 138a retrofit, for instance.)

The automatic doesn't necessarily hurt value. It's an unusual feature. Automatics were rare, and most were replaced with standards, making surviving automatics even more rare. (Of course it's not a "desirable" feature from a driving perspective.) FAIW, I had a '66 Mustang with factory power steering -- also an unusual feature for that year. The design of the PS was not particularly good, but mine was functional and in good shape. I think it contributed greatly to the value of the car, mostly as a curiosity (as it was done with hydraulic cylinders). That '76 is a nice looking car!

Jai, bring us along with you on the diagnostics: You've determined fuel is not the problem because the car won't start even when you spray starter fluid in the intake?

You don't see much chrome anymore on cars, which is why I'd pick chrome. And I've always admired wire spoke wheels like rossiz has, but I also recognize they're a PITA to care for!

I believe it's the "follow this topic" button at the top. I think you would select "instant."

Jai, you're looking at all this stuff via email? Why not just go to the website? (You can bookmark it for ease of use.) Here's the link to the S30 forum: http://www.classiczcars.com/forum/4-1st-generation-z-s30-240z-260z-280z/ You'll find all the threads neatly organized there.

Your neighbor could be right. That's how my fuel pump went -- similar to all that you have described. The first time the engine died was in the middle of a 100 mi trip. The second time it ran for 30 min. The next few times maybe 15 min. Then 10. The way I tested my pump was to put a pressure gauge on a T-fitting inline between the fuel filter and fuel rail. Then I removed the hose from the fuel return end of the rail, attached a long vinyl tube, and stuck the other end into the filler neck of the gas tank. Then I hot-wired power to the fuel pump and ran it in the driveway, while watching pressure and flow rate (how fast fuel was ejected from the return and then pouring back into the tank. I found that flow rate slowly dropped until there was no more return flow, and then the pressure started dropping from there. I replaced the pump, and all was good. Having said that, it's important that you actually test the pump before replacing it. Parts are expensive, and OEM parts are diminishing in supply. And the problem could easily be something else. You should also look for rust in your tank, and you should confirm with the starter fluid that your ignition is still working when the car dies. And you should also probably have a look at the fuel lines and vent system to see if everything looks good. So you have some work yet. But I do agree with your neighbor that a failing pump should be on your short-list of possible culprits.

^^^^ About the silica gel idea -- not a bad idea! But most people don't really know how the stuff works. As a photographer in a soupy climate, I use the stuff a lot. It actually buffers moisture, more than absorbing it. To be clear, it WILL absorb moisture, but only until it reaches a equilibrium. And you can reach that equilibrium point much faster than you might think. The main benefit of silica gel is that is absorbs moisture as the air cools (and RH tries to rise), but it also gives off moisture when temperature rises and RH tries to fall. In a perfectly sealed space (e.g. the gast tank, hopefully), humidity will remain stabilized at some value. In a leaky space (probably the cabin of your car), there will be enough air exchange past leaky seals and through vents that you could never hope to keep the humidity at any target other than the AVERAGE humidity of your garage. If you want to control humidity, my recommendation would be to put a dehumidifier in the garage space and crack the windows. Dehumidification during the winter in a cold space can be challenging. I've had great success with the Ecoseb Simple desiccant dehumidifier, which doesn't really care about temperature and operates about as efficiently at any temp. It will also warm the garage very slightly. I also like the idea of the silica gel bags in the gas tank. I would think that would be done best by draining the gas and then letting it all evaporate. Then put maybe 100g of silica gel (either loose or in packet form) into a cotton sock, hung by the gas cap into the tank. If you get indicator gel, it will change color as it takes on moisture. Periodically remove the gel, and dehydrate it (driving it to a lower RH set point). You can do this very easily during the summer by throwing it in the hot attic for a few days. (Seal it up in a zip-loc bag whenever the attic is not HOT, so that it doesn't re-absorb moisture.) During the winter, you can do this by putting the desiccant in a stream of furnace air for a few days. But of course if you do all of this, you can't start your car every month or two!

Wow! No kidding!? I have to say, though, that there's something sort of cool about that antique car smell. It takes decades for it to mature, like a fine wine.

What do your plugs look like? It would be interesting if one is rather oil-fouled and the others are OK. Interesting about the valve stem condoms. Not having those, it should be pretty easy to put some cheap (and thin!) heat shrink tubing over the end of the valve stem. Isn't Datsunparts LLC that outfit that sells major assemblies (engines, cylinder heads, etc.) that are very pretty but mechanically very shabby? Or am I thinking of some other vender? The location (Rancho Cucamonga, CA) seems to ping my memory. And now he's changing the name to California Datsun? I wonder why.

Jai, that solid blue wire with the bullet connector MIGHT run from the (-) terminal of your coil to the tachometer. However, as I said before, your ECU is being triggered, and the blue wire at the coil is common to both the ECU and tachometer. That's how it's reflected in the '76 schematic diagram too. It's possible you've got some modification going on. But blue is the correct color code for the trigger wire. If you know how to use a multimeter, you should test for continuity of the blue wires to the #1 pin of the ECU and to the tachometer (I think the terminal labeled "S"). If you don't know how to use a meter, you should find someone who does. The worst thing you can do is to hook up wires where you think they might go (without confirming what they are). That's a recipe for having stuff blow up.