FastWoman

So his car doesn't go very fast, but it sure is efficient!

Thanks Ztrain and Madkaw! So sequential isn't that big a deal... I can believe that. So for the ignition, is the distributor gutted/modded to be a cam angle sensor? Are there kits for that? Having the ignition under ECM control certainly sounds like the way to go.

That sounds like a good idea, Steve! I might just do that. I looked at the MS equipment on the DIYAutoTune website and have to say all the bells and whistles were dizzying. I see I can do everything from basic fuel control with banked injector firing to ignition control with advance and sequential injection. (How important IS sequential injection?) I can see I'll need to do quite a lot of studying just to determine what it is I might want to buy/do. But the O2 sensor is certainly a good start. I think I'll ruminate on that a bit.

Argneist, no need for a picture. You're already describing the doobob in question -- a round thingie that mounts to the front of the throttle body. It has a white plastic nipple that is not supposed to have any vacuum line on it, appearances to the contrary. Check yours to see if it works OK. Just open your throttle by hand. You should see the protrusion on the dashpot move outwards. Then let the throttle close. The protrusion should be pushed back in by the lever on the throttle. The dashpot should slow the throttle closure right near the end of travel. If the dashpot is frozen or moves roughly, you might be able to get it working again by squirting WD-40 inside and working the thing. Dunno. That worked for my '75 Z back in the 80's.

That's about as good a success story as I've seen! Congrats, Argneist! You should be very proud! And hey, congrats for finally having the courage to tweak your AFM!

Is that a working OEM pump you're about to mod? :tapemouth Why not use the pump of some common, more modern EFI car? Maybe a Chevy Cobalt. Sell your working pump on Ebay to someone with a 280, if you don't want/need it. Do it for karma's sake! :classic:

Sometimes it's not what comes out, but what goes in. I'm reminded of a friend's little boy who came into the kitchen and said, "Mommy, I filled your gas tank for you." Sure enough, he had filled it very carefully with sand. And then there are big people who can put things in your tank. It doesn't happen but once in a very blue moon to some unlucky person, but it does happen. Oddly, I doubt someone would drain off your tank with the bolt on the bottom. The universal tool of choice is still a rubber hose. Maybe that will change, but I never heard of anyone draining from the bottom back in the 70's when people were having their gas stolen. Generally speaking, thieves are incredibly stupid.

... and BMW -- Bayerische Motoren Werke (Bavarian Motor Works)

Thanks, guys! It sounds like the conversion might be worth doing. I confess there's a side of me that wants to preserve the original Bosch L-Jetronic system, but there's also a side of me that wants a more affordable and better running daily driver. What would you estimate my time commitment to be in making this conversion, considering that I'm competent with EFI engines, but a newbie with MegaSquirt?

Hi all, As fuel prices continue to rise, I'm wondering what the potential is of our L28 (or L24/26) engines is. I currently get about 19 mpg combined. I didn't worry about that sort of mileage as a kid, when gas was cheap, but these days that's what you would expect from a pickup truck, and 19 mpg will run you broke in a daily driver. I have to believe that an engine is an engine is an engine when it comes to basic operating efficiency. So long as they're able to pull approximately the same vacuum, they should be operating with roughly the same efficiency, right -- at least for cruising? Maybe the hp:weight ratio is lower on our engines than on a modern 24 valve engine, but weight doesn't impact highway miles. And of course the Z has sexy but inefficient lines. A more aerodynamic shape would be that of the egg-shaped Prius. That's obvious in hindsight, I suppose. But is that enough to limit us to only 20'ish mpg -- maybe the mid 20's on the highway? I'm wondering how inefficient our EFI systems are. Could we squeeze several more mpg out of a MegaSquirt system, not to mention better performance? Is there an efficiency/performance incentive out there for making the switch?

If you had said "5 years," that might have been cause for some worry. IMO, you should check your oil level, drain/replace the old gas, and try firing it up. If it runs, then add a bit of SeaFoam in your fuel to clean varnish from the carb. Go for a nice drive, and when you return home, change the oil. If it doesn't run, you probably have to clean out your carbs.

You can actually take the AFM apart. There are screws, glopped over with glue, on the "waffle" side of the thing. I suspect the main shaft runs through a bearing that is pressed into place in the main housing. I've not actually been inside one of these things, so I can't tell you anything more. I'm a little bit surprised that your engine would run much at all with an open temp sender. I once forgot to plug in my CTS, and I was blowing black smoke out the exhaust. I'm just making a guess here: I suspect you were running a bit rich before you straightened out the CTS, and now you're running a bit lean -- due to a large vacuum leak. FAIW, my biggest vacuum leak was between the intake and head on my #5 and #6. Compounding the problem, I had sooty exhaust blowing from exhaust manifold leaks on the back end of the engine, so exhaust gasses were getting sucked up directly into the #5 and 6 intake. I could tell this because of the soot residue leading from my exhaust ports through to the intake ports. That is, there was soot underneath my intake and exhaust manifold gaskets. Maybe you could do a repeat of the yogurt cup test with a friend who smokes. Just fill the intake up with with a chest full of cigarette smoke, and see where it blows out.

Well, since the FPR comes after the injectors and before the return, I can't see how the design of the FPR would in any way impact flow to the injectors. There's no doubt the stock FPR is very tight, and it works very well. I've admittedly never tried an Aeromotive. Eric, I've been having trouble with hot starts lately too -- the same as you describe. Unline on your car, my fuel rail IS insulated, albeit rather minimally (a layer a rubber hose, wrapped in silicone rubber). Also my OEM fuel pump is brand new. Other than that, everything is new except the FPR and cold start valve. I've checked both, and both are functioning correctly. Oh, I have the cheap Standard Ignition injectors, but I have no reason to believe they're acting up. I don't honestly know how long my fuel rail holds pressure, but I'm 99% certain it has adequate pressure for a start after the 10 min or so that it takes for my car to have a rough start. To be clear, I seem to have a miss that results in an abnormally low idle and clears after I take off down the road. BTW, like Zed, I do prime my fuel rail for a few seconds before every start, so it's not that I don't have pressure. I don't know if it's relevant, but if I leave my car sitting overnight, I'll sometimes hear a bubble or two pass through the fuel pump when I prime it. (The whine briefly changes pitch.) However, I have absolutely ZERO problem with a cold start. The engine fires up instantly and idles normally. My own pet theory about the hard starting is that the CTS and air temp sender become heat-soaked, resulting in lean running for a short time. It would be interesting to see if jumpering the TPS connector for full throttle enrichment -- or unplugging the vacuum line to the FPR -- would compensate the rough running on warm restart. If so, it would support my heat-soaked-sensors theory.

Well, to be honest, I read the "turn on your car" thing much more on a Miata forum where I'm also active. However, it seems to be mostly kids using the expression -- usually the ones who seem like they would never get their fingernails dirty -- sort of like my stepson who popped a fan belt and told me he "broke a ball bearing or something."

Yeah, kinda... Yeah, kinda...

OK, I just have to ask this, because it sounds pretty funny to me. There seems to be a generational trend for kids to speak of "turning on" or "turning off" an engine, almost as though they were flipping a switch or something. This sounds every bit as peculiar to me as "you guys" and especially "yooz guys" sounded to me as I relocated from South to North. So do you think this "turning on/off" language related to the relative ease of starting a modern engine? Some cars even have "start" buttons, sometimes even starting by remote control. Back long before MY day, someone would have to CRANK an engine by hand. No electric starters. I have no question nobody would have referred to "turning on" an engine back then. Rather, it would be "crank it" or "fire it up." It would be very much like starting a lawnmower with a pull cord. As far as I'm aware, nobody "turns on" a lawnmower, but I could be wrong. In my day, cars were sometimes fussy, and there was a sequence of events even on a well-running car to get the thing fired up. At the very least, it would take an accelerator pedal pump or two, perhaps a pulling of a choke knob, and then a crank. This wouldn't be a "turning on" process, but rather a "starting the engine" process. But nowadays, I guess you can push a button -- "turn on/off" So is this where the expression comes from -- from the ease of starting -- from its effortless, one-step, fool-proof nature? Another question: Do any of you (especially the 240 folks) feel a sense of pride that your startup sequence ISN'T via the mindless push of a button? Wouldn't you shrivel up just a bit inside if you had to tell someone you "turned on/off" your Z? Or is that just me?

So I went to the auto parts store the other day to buy an oil change supplies. I had the guy look up a Mobil 1 filter for me. When he walked with me to the filter area to grab the thing, he looked at it, puzzled, shaking his head, and said, "Naaaaah, there's NO WAY this is the right size filter for that little car." I responded, "Well, they do seem to be a bit smaller these days, but maybe I'm just imagining it."

Exhaust pops on deceleration are more symptomatic of (slightly) rich running, but I wouldn't stress on it too much. Just check your TPS to make certain the switch does close when you come off the gas pedal. This cuts fuel delivery on deceleration when the engine speed is >2500 rpm. I don't know about the sputtering. I assume you mean it does this on acceleration? Maybe your mix still isn't quite spot-on, and you might still need to tweak a bit. I'd suggest putting in a new set of plugs, running them for a couple hundred miles, and reading them. The insulators should be a nice mocha color, not sooty/black (rich) or chalky/white (lean). You might still have intake leaks, so you might not be home-free. As I said before, there's no ambiguity in the yogurt cup test. You should be able to just about empty your lungs into your engine, and you'll build up a bit of pressure. That pressure should take maybe 20 sec to (mostly) leak away. If it leaks away in maybe 5 sec, you've got a leak. Again, you should see a BIG difference in how fast the pressure dissipates when you pull off your little HVAC vacuum hose. Anyway, 18.5 mpg is about what you should expect. I think I get about 19 combined mileage. That seems to be a rather typical real world figure. These aren't the most efficient cars in the world!

Just contact the seller, and ask him if he'll sell you a set of 10 connectors -- or maybe 11 for the spare. He can put together a custom auction for you. With 11 connectors, you can replace all of the 2-conductor Bosch-type EFI connections and have a spare for testing work. I forget how the BCDD works, and I don't know whether having it disconnected might result in problems. However, the BCDD on most of our engines has long since stopped working, with replacements NLA. Many/most have already been removed.

None of this should have anything to do with the exhaust. I'd look for bad/crusty/dirty connections and crumbly connectors. You can buy all of the 2-conductor Bosch style connectors from a seller named f0rrest on Ebay. http://cgi.ebay.com/ebaymotors/injector-connector-kit-6pc-datsun-280z-280zx-300zx-_W0QQcmdZViewItemQQhashZitem43a04f8954QQitemZ290452375892QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories Same connectors for the CTS, cold start valve, air regulator, and thermotime switch. Have the f0rrest put together a 10-connector set for you, or order another set for a 4 cyl Jeep. I'd also suggest getting an extra connector to use for testing/debugging.

Are you talking about the coolant temperature sensor (2-conductor Bosch style connector, smaller doodad, sends a temp reading to the ECU)? Perhaps the thermotime switch (2-conductor Bosch style connector, larger doodad right next to the smaller one, turns the cold start injector on and off)? I assume you're not talking about the temp sender with the single wire that runs to the temp gauge. I'm guessing you're talking about the thermotime switch. If so, you're right that it will only help you with COLD starts (I think below 50F). The ground on the switch is the body itself. One wire on the connector operates an electric heating element, and the other wire switches the cold start valve. The connector is wired in parallel to the cold start valve connector. You wouldn't want to ground either wire. Grounding the heater wire would do nothing. Grounding the other wire would have your cold start valve constantly spraying. BTW, you should download a free copy of Nissan's factory service manual: www.xenons30.com It has all the wiring diagrams you'll need. All mysteries of the Z universe will be revealed within!

On the other hand, if you get an AZ lifetime warranted rebuilt part, that's the last time you have to lay down money. Your only investment is time, but an alternator R&R is pretty easy, at least in a Z. My first AZ alternator regulated a bit too high, so I returned to the store and swapped it for another that worked correctly. That was an extra hour of my time, but the price was worth it. Of course I would NEVER get an AZ rebuilt part such as a brake caliper, as that's a safety item. I want it done right, and I only trust myself to do the rebuild. (Nobody cares as much as I do.) Besides that's a harder part to R&R, and I don't want to waste my time with doing it twice. But an alternator or a distributor... no problem! Easy breezy!

I'm guessing that's Blue's handy work. If not all his, it seems to be largely his. It's a wonderful resource! If I understand what you described, before you loosened the spring a tiny bit, you had tightened it a lot more. So you would have been running rich. The weird thing is that extremely lean running can appear superficially like rich running, in that the incomplete combustion results in tons of soot deposition. Also the exhaust smells similar because of unburnt hydrocarbons in both cases. The other thing is that your engine had multiple issues, just like almost every other old engine I've seen. Some issues lean out the mix (e.g. vacuum leaks), and some richen it (the tampering someone did with your AFM). I bet someone adjusted the AFM so far out of whack once to compensate for a massive vacuum leak. Some of these problems may cancel each other, but they do so at the detriment of the overall operation and responsiveness. Then when you fix one problem (e.g. your vacuum leaks), it might make the engine run worse, not better. It becomes tempting to undo the fix, but that's not a path to putting the engine right. Anyway, you persevered, and you got the payoff in the end.

Bingo! Another hack's "fix" undone! Cool!

There's a diagram in my '78 FSM. Isn't there one in the '73 FSM?