FastWoman

And another note: Blue recommends the 1-turn control-type potentiometers such as you would turn with a knob. However, this is actually a poor choice. It is too easy to knock one of these out of align. My most favored choice would be a 20-turn trim-type potentiometer like this one: 043P103 - VISHAY SPECTROL - TRIMMER, POTENTIOMETER, 10KOHM | Newark Adjusting from one end to the other requires turning the little worm screw with a screwdriver. It's very precise and very hard to knock out of align. The potentiometer is also extremely well sealed and will not easily corrode or get dirty inside. But if you don't want to go that route, then you should at least use SOME form of trim potentiometer: https://www.google.com/search?q=trim+potentiometer&rls=com.microsoft:en-US:IE-Address&tbm=isch&tbo=u&source=univ&sa=X&ei=mEbtUcnhEuSqyAHEvYHYCQ&ved=0CGMQsAQ&biw=1237&bih=837 If it's not completely sealed, like the linear 20-turn ones, then my advice would be to use one that's open enough that you can smear the resistance strip with dielectric grease -- for instance this style, which you adjust with a screwdriver in the center hole: http://www.ictradenet.com/models_pic/EVN-64AA00B32.JPG

A lot of advice, mostly correct. The shorting of those two pins -- the wiper contact (middle) with one of the strip contacts (end) -- is a method used by better electronics designers to ensure that the resistance never gets greater than that of the strip. If for any reason the contact between the wiper and the strip gets dirty or corroded, this would prevent the resistance from jumping periodically to infinity. It's a small refinement and is not absolutely necessary (or in any way particularly consequential). MOST potentiometers are built like this: FED: Intro to Physical Computing So you can imagine the internals, even though you can't see them. The resistance from A to B is always the stated resistance of the potentiometer (e.g. 5 kOhm). If you turn the wiper all the way to the "B" end of the resistance strip, as shown in the diagram, the resistance will be (almost) zero from W to B, will be the stated resistance of the potentiometer (e.g. 5kOhm) from A to W. If you turn the wiper halfway, the resistance between A and W will be equal to that from W to B, which will be half the stated resistance of the potentiometer (e.g. 2.5 kOhm). If you short A and W together, then the resistance from A to B will be the stated value of the potentiometer (e.g. 5kOhm) when the wiper is turned all the way to the A end of the strip, and it will be zero when turned to the B end. Wired this way, and again referring to the diagram, CCW (towards A) would be richer, and CW (towards would be leaner.

BTW, Wade, there is nothing wrong with the ECU box or the wires. The engine compartment connectors might be a bit crusty, but they're easily replaceable (another project). Nobody needs a completely new harness. An upgrade from AFM to MAP could simply involve the re-purposing of the AFM wires. That could be accompanied internally (inside the ECU box) by the shifting of a jumper connection or the substituting of an internal connector. That could be achieved in the engine compartment either with a plug-in adapter, for those terrified to make their own connections (such Z owners exist and are probably in the majority) or with a quick snip/rewire job for those comfortable working with wire. The adapter would be appealing even to someone like me, because it would keep the car reconfigurable to stock if needed. I don't like snipping wires, even when I do. And it's not because I'm even the slightest bit shy about electronics.

This would work for me as well. But what I would MOST like, and what I think many Z owners would also like, is an easy drop-in replacement. This would be a solution for someone who is too busy with other stuff to spend days tweaking their Z. It would need to handle I/O with existing equipment, such as the AFM, but it should ideally be expandable/improvable for when life is no longer in the way, so to speak. And Wade points out something very important: It's not the antiquity of a distributor that's at issue with our ignition, but rather that our advance mechanisms are falling apart. The breaker plates typically get stuck and may randomly stick at various stages of advance. Rebuilt units are apparently getting scarce, and the rebuilding process comes with some risk of damage to the shaft. So to get a Z running "right," usually involves straightening out the ignition somehow. In my case, I was able to do it with a rebuilt OEM distributor. Many people upgrade to a Pertronix distributor/ignition system. I think it would also be feasible to go with a crank sensor and a wasted spark ignition. But what we should NOT do is to rely on the OEM distributor to provide an accurate timing input going into the future, barring some sort of modification like mechanically fixing the breaker plate in place (now there's an idea) and handing over all advance to the new ECU.

A tragedy averted! Welcome to Virginia, Sean! So are you driving your Z here? A big road adventure?

Hi Len, Welcome back! I'm afraid I'm now in "life gets in the way" mode, but I can certainly find time for a 10 min PnP swap. My Z runs pretty well, but I recognize the ECU isn't entirely stable. I think it's needs tweaks every now and again, and I haven't stayed on top of that. What I would eventually like to do is to hand over control of the ignition to the ECU, as I recognize the distributor advance mechanism is one of the weak links in these engines. Unfortunately rebuilds have spotty availability. I feel ECU control of the advance would give us quite a bit more efficiency in these engines, so that's a worthwhile goal. I would also love to run a MSD ignition system, but that mucks with the ECU, as the spark is used to trigger it. I suppose I'd need a Pertronix distributor that would put out a clean square wave that I could split between the ECU, the tach, and the MSD? I can understand your not wanting to take on every bell and whistle up front, but it will be great if you can have forward compatibility to future ECU versions, such that the programming can be transferred forward and the new capabilities then invoked. I would suggest that your design also utilize an internal connector (inside the ECU box) that can be used to swap out boards. Perhaps you could use a card edge connector. That way it would not be necessary for someone to mail in their ECU and suffer down-time between upgrades. And I'm curious: Would it be advantageous to have heat sink capabilities, for instance for the power transistors that actuate the injectors? Maybe passive heat sinking to the body, where the ECU mounts? Maybe a cooling fan? Otherwise the box might become a bit of an oven. Anyway, I think much of your market for this ECU will be from the "life gets in the way" crowd, and I'm currently one of them. I think the initial PnP aspect, with the ability to improve engine control incrementally (an IAC here, a MAP sensor there) will have very broad appeal. So talking business here, what sort of arrangements are you proposing with your initial guinea pigs? We'll be contributing by helping you to debug your system. I presume you sell to us at a "not ready for prime time" discount? Also, I hate to trash any boards. I can send you an empty ECU box (my spare) with the connector. Does that work?

Wade, my gripe is ONLY with the side curtain airbags and elderly control electronics. I'm all in favor of properly functioning frontal airbags. In fact I was an early adopter, having paid for an optional airbag system in my '92 Saturn. Here's the source of my gripe, besides the bag that randomly popped off in my car: When I drive, I am very conscious of the airbags. I like to drive with my arm at the top of the wheel, and I realize in either of my two airbag-equipped cars I shouldn't do this, because my arm might be driven into my face. So I hold the wheel at 10 and 2, and I do the left-right shuffle when steering around corners. Fair enough. But what I can't control as easily is my passengers. I'll be driving along and will notice that one of them has shoved a pillow against a window and is sleeping right in the airbag deployment zone. Yikes! So I wake the person up and sternly order them not to do that. And then I'll see another passenger with an arm propped in the window. Again, more stern orders. People really have to think about how they sit and ride in these airbag equipped cars, AND THEY SELDOM DO. That makes me nervous. And I also love old cars, but I don't love old airbag systems. So there I have a conflict. I see no way collectors/enthusiasts can possibly maintain a safe airbag system decades after a car goes out of production. If I could have replaced my Miata's airbag control module with a part I'd consider reliable, I'd have done it. (No side airbags on that car!) But I couldn't, and I wasn't about to let that car's airbags pop off randomly the way the bag in my #$% did. Anyway, please don't misunderstand me. I'm saying that airbags are a mixed bag. They have to be used wisely, and they seldom are. And I will never trust the side airbags. Ever.

Ethanol will reliably screw up aluminum carburetors, but I've never had any difficulties with fuel injected vehicles. I put 87 E10 in my '78, which is my daily driver. I've been doing this for a few years now. Prior to that, I ran 89 E10 in my '75 Z from 1983'ish to 1994, with no problems. For anything that sits, I use either no-ethanol gas or gas with stabilizer.

Since your car is at a dealership, consider the following to CONFIRM the ignition failure: 1. Borrow a can of starter fluid from the service dept and try what I suggested above. 2. Borrow a timing light, and see if it flashes when you crank. Sometimes a spark is hard to see in the daylight, especially if you don't have an appropriate gap. You might also have a weak ignition but a failure point that lies elsewhere. Most old cars have multiple problems. Only rare ones are completely straight. FAIW, fuel pumps also fail when overheating. Or at least mine did.

Jordan, you're trying to measure the signal of the distributor's reluctor. You can of course do that, but you probably have to use either an oscilloscope or a needle-movement volt meter, and your results won't tell you anything about whether the ignition module is failing. (It will tell you only whether the signal to the ignition module has gone bad.) Here's a quick fuel/spark test: Buy a can of starter fluid. Run the engine until it dies. Then pull off one of the vacuum hoses from the intake manifold, spray some starter fluid inside the manifold, replace the hose, and try firing the engine up. If it runs (but only very briefly), you have spark and no fuel. If it doesn't run, you probably have bad ignition. FAIW, if it's the ignition module, it will die faster if your engine is running faster (because it's working harder to create sparks at a higher rate). If it's something like the fuel pump, which is under the same load regardless of engine speed, it will tend to die in a more consistent time. So you might try running your engine at a faster idle to see if it dies faster. That will give you another clue.

These are essential tools! I'm glad you have them on order. FAIW, I have a fuel pressure gauge permanently installed in my engine compartment. I picked up a very cheap pressure gauge from the hardware store, screwed it into a T-fitting with a couple of barbs, and installed it inline between the fuel filter and fuel rail. Total cost was something like $10. It's perhaps not dead-on accurate, but it's not bad, and it's always there if I ever find myself stuck on the side of the road.

Well maintained, I don't think these cars are unsafe. As a kid driving a '75 Z everyday, I was clobbered quite a few times. Nothing particularly dramatic, but also no injuries. Lack of antilock brakes might be an issue that could potentially have you rear-ending someone, assuming you don't do a perfect job of squeeze braking. Air bags can help or hurt. I had parked and was shutting down the engine of one modern car when the side airbag blew up and burned my left arm. It hurt quite a lot and was surprisingly disorienting. If it had happened while I was driving, I would have certainly wrecked and possibly killed myself and/or someone else. The airbag module also died in my '94 Miata, with no replacement parts available. Some people try to fix this module, resulting possibly in a dangerous/unsafe/unreliable airbag system. I simply removed mine. So an old airbag system might not be safe. Side curtain airbags might not be safe even in a properly functioning vehicle. The NHTSA database is fully of narratives of side curtain airbag failures -- either spontaneous deployments or deployment failures. It seems there is too little time to gather reliable data before the control module must make a decision whether to deploy the side airbags, so a bad decision is often made. There is more time for frontal bags, which are much safer and more reliable. Unfortunately vehicles with frontal bags and no side bags are older and do not have proportional airbags (which are safer). When side curtain airbags deploy, they can also cause unexpected injuries. If a passenger is leaning against the window, for instance (e.g. sleeping on a long trip), the bag can come down on his/her head and cause brain/neck injury. An arm propped in the window can be broken. Of course the frontal bags are not without issue either, for instance if you're seated too close to the airbag. IMO the three-point shoulder/lap belt system is pretty solid if it is used correctly. My Z might not be as safe as a Volvo brick, but I bet it's as safe as (or perhaps sometimes even safer than) modern sports cars in its weight class, including my '94 Miata or that other sports car I can't mention (because of a legal agreement) whose airbag blew up in my driveway. (BTW, of the three cars pictured below, only one of them is modern enough to have an airbag system. Just thought you'd be interested. )

Kelly, congrats on the fuel issue! Making progress! I don't really know ATs very well, never having owned one except briefly, but I believe they up-shift when the engine vacuum climbs to a certain value. I believe this is done by a "modulator." If your engine isn't running efficiently (probably because of mixture or timing issues), the vacuum might not easily reach that threshold level for up-shifting. That would be my guess. I think you will know a lot more about your engine if you can hook up a cheap vacuum gauge. I would guess two things about your engine: 1. Running lean (common issue with '78 Z) 2. Stuck/sticking breaker plate in your distributor (i.e. messed up timing). This is a common issue with all Z's.

Not on MY Z! It seems to me that this mount would create a lot of action on a relatively small patch of sheet metal with a lot of mechanical advantage. That can't be good. Even worse, what if the suction cup looses its vacuum? You'd lose the bike, which would possibly leave scrapes on your roof, and then you'd be liable for damage to vehicles behind you.

That's almost certainly the problem. However, I'd also not drive the car long distances without the hatch weather stripping, at least without the windows rolled down. That just invites carbon monoxide into the cabin. (It gets sucked inside from the turbulent air just behind the car -- common route of entry.)

FAIW, running your battery down that far sucks much of the life out of it and can possibly kill it. You shouldn't try starting your car on a weak battery. Charge it first.

Hi Steve, I've only glanced at the MS literature long enough to appreciate that a MS retrofit isn't a plug 'n play process and that it will take a bit of time and study. Unfortunately time is a scarce commodity for me at the moment, so I can't be much more than an interested observer. Perhaps I can contribute moral support?

Madkaw, I'm not ready to jump on board with the MS yet, but I think I'll get there before too much longer. I think my system is drifting even leaner, and I will need to re-tune when I find a few moments. So I'm very interested in this thread.

Yes, I just poured gas into the inlet until it was full and then kept it "upright" until I could get the hoses on it.

Hi Kelly, As I recall, black is gnd and blue/green (?) is hot on my '78. You should double-check the + and - markings on the fuel pump to be certain you've got the polarity straight. We're all prone to mistakes. To see if your pump is pumping, do as Zed suggested. Just connect a length of fuel line to a convenient point (e.g. main fuel filter outlet), and drop the other end into a gas can. Crank the pump, and see whether fuel comes out. FAIW, I think I filled my new fuel pump with gasoline before installing it. Your new pump might not be getting gasoline and might just be whirring the air around. Oh, and it's perfectly safe to hold the key in the start position (with the starter wire removed) as long as you wish. Nothing will burn up.

Glad to see you're making progress! Maybe the chunk of debris was causing cavitation, resulting in the whining? Hopefully your annoying noise will be gone. My own fuel pump came with the pink bondo (?) terminals, like siteunseen's. My car had a 15 year history of Nissan dealer service before I bought it, so perhaps it was some sort of Nissan -endorsed material/compound. I used 5200 to seal mine when I was done. It will be great when you get to finger the AFM counterweight. I think you'll learn a lot about your engine then.

TVS = Throttle Valve Sensor? (a.k.a. TPS -- Throttle Position Sensor?) No, I'm talking about the airflow meter, which is the device between the air cleaner and the throttle assembly. It has a vane inside that meters the airflow. The ECU (Engine Control Unit, a.k.a. "computer") delivers fuel according to the amount of air metered. If you move the vane by hand, you can change how much fuel is delivered. I'm probably the one who indicated an extreme lean condition can result in misfiring, resulting in carbon buildup. Perhaps this only happens with a marginal ignition (which mine was at that time). There's very little information beyond the dogma that a (somewhat) lean condition results in white, chalky plugs. However, I know for a fact (because it happened to me) that an extreme lean condition (that results in intake backfires) can result in carbon fouling. The reason for the backfire, BTW, is that the mixture is so lean that it burns neither well nor quickly. It's because it burns so slowly that a combustion cycle can persist into the following intake stroke, creating the backfire (or so it was explained to me).

Oh, and FAIW, 1978 seems to be the year of the "lean drift." There's something about the '78 ECU!

Well, the good news (to me) is that your plugs are fairly consistent from 1 to 6 -- no wild outliers. That suggests to me that your injectors are probably not clogged. (If they were, it would be to different degrees with each one.) Aside from the hot ground strap, I'd say your plugs look a lot like mine did when I was running rather lean -- lots of carbon, at least for plugs that haven't been run very long. I realize carbon fouling is a classic indication of a rich mixture, but in my experience if the mixture is lean enough to cause partial misfiring (whereby a slow, incomplete combustion results in backfire through the intake), then it can also cause carbon fouling. One great way to determine whether your mix is out of whack (and in what direction) is to remove the plastic cover from the side of the AFM and to finger the counterweight to see how it impacts the idle. If fingering it slightly CCW causes the engine speed to pick up a lot, that would suggest your engine is running lean. If fingering it slightly CW improves idle, you've got a rich mixture. Ideally, fingering it in either direction will result in a slight drop in engine speed. Of course this is at idle, and what matters most is off idle. But still I found that the proper mix at idle gave me the best mix on the road. There's an idle mixture screw on the bottom, outlet side of the AFM, but I've not found it to do much of anything. I have mine set 5 turns open.

No problem! We'll be here!