FastWoman

Holy travesty, Batman!

Hi Everyone, I just finished watching "Safety Not Guaranteed" on Netflix. It's about a guy who runs an ad searching for a time travel companion and the girl reporter who answers the ad to do a story about him. It's a quirky comedy drama romance that was quite a lot of fun to watch. (I gave it 5 stars.) Watch Safety Not Guaranteed Online | Netflix If you go to the above link, you'll see the familiar rooftop/windshield of the car the guy drives -- a 1977 Sunburst Yellow (411), non-ZZZAP decal'ed 2+2, not in the best of shape, but with a lot of spunk. I enjoyed the movie for reasons other than the car, but the car certainly added to my enjoyment. The location was supposedly Washington. I wonder whose car that was. Did they do ZZZAP cars in 2+2?

I've spied two other Z's on the road in my area, not counting the several Z's parked in front of the local Z specialty shop. Both looked very nice. One was a red convertible (!!) with essentially no top -- a fair weather car. We crossed paths on the residential street where our accountant has his home office, and we had a long'ish chat about our cars until it became apparent we were blocking traffic. The second was a pristine copper '78 with a "for sale" sign on it -- nice price, too -- $4500. I seriously thought about buying it, but I'm not into brown and butterscotch. I saw the seller driving the car around town about a week later, and then he ended up selling it to a dealership. My own Z is about the only one in regular service as a daily driver in my general area. Perhaps it's not as visible as many DD's, because I don't rack up that many miles per year. However, other Z lovers (mostly people who parted with their beloved Z's many years ago) do seem to recognize and remember me.

I wish I had gotten to know him better. I'm sorry to hear the sad news!

Just speaking for myself, I bought the car running lean, and I fixed/replaced/verified/reconditioned EVERY part of the EFI, bringing EVERYTHING up to spec. And still I was running lean. And yes, I even tried real, non-ethanol gas, which makes a small difference, but doesn't really solve the problem. All that was left was the ECU. I bought another '78 ECU off of ebay, and the engine ran pretty much the same. Then I thought about all the old electronics I've fixed/adjusted/restored in my lifetime, including tube-type, component transistor, and early linear IC. And I thought about the hostile conditions (lots of heat!) under which the ECU had to operate for decades. I've seen lots of drift in lots of components manifested in wonky calibration, as viewed on an oscilloscope. Components do drift, and semiconductors do break down. Even a linear IC, with its numerous feedback circuits, will ultimately break down. More significantly, add to that that capacitors lose their capacitance, and therefore charge faster than they should, hence faster voltage ramps and shorter trigger times. It made sense to me that the base pulse might be shortened, and so I took measures to lengthen it.

IMO, just buy the connectors, and make your own! It's just wire, connectors, and electrical tape. If you want to get fancy, wrap with silicone rubber tape.

Ouch! Sorry to hear about that, Horseman! I hope you've healed well and that your Z will live to drive another day.

@darom: Glad it all worked out for you! Nice implementation of the pot! @Kjeese: I adjusted my pot on the basis of a few things: (1) Exhaust flow and smell, (2) idle vacuum/RPM, (3) off-idle vacuum under constant load (A/C compressor), (4) plug color. I found a happy, all-around middle ground that gave me good results on all of these.

Hot injectors + low operating fuel pressures (characteristic of early EFI systems) + modern ethanol fuel (developed at the tail end of the 1970's and not designed for those working pressures) + more volatile winter fuel formulations = flash vaporization of fuel inside your injectors. The ZX engines had injector cooling fans for a reason. I think the only cure is to find a better formulation of gasoline or install a ZX fan. Hood vents also help, although you would already have those. (You could of course remove the rain pan on the driver-side vent to increase ventilation.) I don't have this problem at this time, although I've had it in the past. I've found opening the hood and letting the engine cool can get you started. I wonder whether it would be useful to put a valve on the return fuel line, so that the fuel pressure could be temporarily elevated to around 45 psi. That might force condensation of the vapor in the injectors. A more elegant approach might be to have a time circuit that would close an electrically actuated valve on the return line for maybe the first 15-20 sec of starting/running. Of course some of our Z's, particularly the later model ones ('77/'78) have lean running issues due to drift in the ECU. If we were to compensate not with adjustments to the AFM main spring or with addition of resistance in the CTS circuit, but rather with an increase in operating fuel pressure, we might just kill two birds with one stone.

I've done that mod, although my ideal resistance is around 2.5k, so I use a 5k pot. Instead of the 1-turn panel-mount pot recommended in the Atlantic-Z writeup, I'd use a 20-turn pot, which adjusts with a screw. My results were excellent, and my engine now runs strong and clean. A couple of notes, though: 1. It makes no sense to do this without first ruling out all other EFI issues, including especially vacuum leaks. 2. You're not really fine-tuning the temp sensor, but rather tricking an analog ECU that's drifted in its accuracy/response over the decades. The '78 ECU frequently drifts leaner as it ages, and the '77 likely does too, being more or less the sister year to the '78.

Hmmmm... Rather than trying to find resistance with a vacuum, have you tried simply forcing the butterfly in different directions to see if you can reproduce the binding? You say there are no wear marks between the butterfly and throttle body, but I really wonder about that, especially since the binding is just off of idle. You might try using a lapping compound (e.g. paint compound) to ease whatever is binding. Apply it sparingly around the throat of the throttle where the butterfly closes. Avoid getting any around the shaft. Then apply the vacuum and work the throttle. If your butterfly is binding somewhere, you'll see black aluminum filings there, AND you'll take off enough thickness of the metals to ease the binding if you keep working the butterfly. However, don't get the stuff in the shaft! When you're done, take it all apart, and clean it thoroughly to get any stray abrasive off/out of it.

Is there any play in the butterfly valve shaft? I wonder whether it's turning in an oval hole.

I don't know your answer, but I'll just ask the obvious... There IS a return spring on the linkage as well, I assume? In addition to the rotary return spring on the throttle body, that is? I've seen Z's where that's been discarded.

Here's how: Make your paper into fiber-reinforced plastic. Impregnate it with something like thinned urethane floor finish, thinned epoxy, wood hardener, etc.

... the irony being that in 1972 women were burning their bras. No '72 anything should have a bra on it, IMO!

Dunno... I see carbon deposits on the head right above the #6 exhaust port. To me that says there's a leak, which is not all that uncommon on these engines. The hazard of having a slow exhaust leak, particularly on an aluminum head, is that the exhaust gasses can slowly erode away the metal, particularly if you also happen to have a lean fuel/air condition. Also carbon monoxide will be wafting around in your engine compartment, and that can make its way into the cabin. This may not be an URGENT repair, but it's probably one you should consider making soon. Until then, you should probably drive with your windows cracked.

I dont' think they do. Lots of O2 sensors are 2-wire. I believe that's the type in my Saturn. They don't really work until they're warmed by the exhaust.

As I understand (from a long-time Nissan service tech), the system really only needs to hold pressure long enough for the engine to cool down. Holding pressure forever is ideal, but 3 hr is probably good enough.

RCB, does Sam the Diesel Man's generic check valve work well? I've not yet heard any feedback on it. I was lucky to find one of the last almost OEM valves, actually a Volvo valve, so I didn't need to order from Sam.

If it's this one offered for a mere 50 bucks from reddat... Datsun 280z Fuel Pump Check Valve Nice | eBay ... then it's the wrong one. In fact what reddat is showing isn't even a fuel pump check valve, but rather a well overpriced air/fuel vapor check valve.

OBD?! Heh... Too rich for my blood. I fold. FAIW, I think an O2 sensor is the way to go. You might be able to get by with less frequent scans if you low-pass the A/D output. Actually that's how I would envision integrating O2 input into an analog design.

Perhaps for future availability/affordability of parts. However, I've not found the electromechanical AARs much more reliable than the type we have on our Z's. They tend to get stuck and need to be cleaned -- at least the stepper motor variety. I haven't made anything since the mid 90's, aside from a circuit I built to turn an airbag light on and off. Much of my test bench equipment is gone -- sold, given away, etc. However, I still have the basics. The single op amps are annoying. I much prefer the quads. My favorite was TI's TL084. Its JFET inputs are very tame, and it works well for narrow voltage ranges, outputting effortlessly to almost 0.5V from the rail voltages. It's still in use, apparently -- now in surface mount. The nice thing about quad op amps is that they all (?) have the same pinout. Captain, I'm ready for ya'! I'll see your fancy mechanical pencil and raise you a slide rule! Ha!

Captain, you're on! You, with your fancy, new-fangled digital wizardry, and me with my old-school analog design that you can adjust with a screwdriver as Gawd intended! Tomo, the stock AAR doesn't need controlling. It simply receives +12 from the IGN circuit and slowly closes as it heats up. Of course an electromechanical AAR would be a nice upgrade. A multivibrator circuit could be used to drive the simple electromagnetic type, based on RPM. A stepper AAR would of course require evil digital circuitry. I have to say that an analog ECU, designed of op amps and adjusted with sealed 20-turn pots, would probably be quite stable. Moreover, if the ICs are socketed, they can all be pulled and replaced to refresh the circuitry every 30 years or so. ;-) I have to say, though, that anybody but me should probably prefer a digital design. However, since I have quite a background with analog circuits, and since that's appropriate to the era of the car, there's just something romantic (to me) about an op amp design. If the car were much older, I would probably enjoy trying to design a fuel injection system running on vacuum tubes. (While the EFI would be an anachronism, I think it would be more of a "creative" anachronism.) Of course you would have to warm up the ECU before even THINKING about turning the key!

Yoshi, FAIW, in the '77 and '78 Z, circulation to the heater core is cut off (via a pneumatic stop ****) when the system isn't in the heating mode, so I'd say circulation through this loop isn't important for proper engine cooling. For instance it's not like a Miata's heater loop, if I remember correctly, which is constantly flowing and important for proper cooling of the #4.

Hardly! I'm afraid most of my Francois is gone too.