FastWoman

I wish I had taken better notes on my stock '78 system when I retrofitted it with HEI. Here's what I recall I did: 1. Remove the stock ignition module, which is under the passenger kick panel. I just unplugged it and left the connector hanging. My objective was to make the retrofit as reversible as possible, so I wanted to leave OEM wiring intact. 2. Remove the wire from the (-) post of the ignition coil that originated from the IM. I folded this wire back on itself and wrapped it neatly into the wiring harness with electrical tape. 3. Wire as diagrammed above. Note: It is also very important to have a good continuity to ground from the mounting holes of the HEI module.

Giving the mechanic the benefit of the doubt, that 45 psi could have been static pressure. But I agree the L-Jetronic is an unusual EFI, and it is extremely important to refer to the FSM, no matter how much you may think you know about cars in general.

All I can do is to cheer Lenny on at this point. Lacking anything more intelligent to say... Go, Lenny, go! Go, Lenny, go!

Shoot! I just threw a bunch of those data tapes out! Shame on me... I save all sorts of junk for just such as this.

Cool! Very well done! BTW, I'm very impressed with your diaphragm!

But honestly, you should just read the #13 pin resistance at the ECU. Just remove the interior driver kick panel, and there's the ECU. Pull off the big, hunkin' connector, and the world's your oyster. We can't emphasize that enough! (Well, Zed gave it a pretty good try, I think -- post 52. ) Nothing will tell you what the ECU "sees" like measurements taken from that connector. Oh, and you had asked about the O2 sensor. (Had that been answered?) The Z don't need no stinking O2 sensor (to paraphrase the movie). The ECU only has open-loop mode, with no lambda feedback. Primitive!

The air temp sensor plays a much more minor role in fine-tuning the mix. I doubt a problem with that sensor would result in the magnitude of problem you're having. Besides that, I don't recall anyone ever having a problem with the thing going out or suffering a bad connection (via the AFM connector). FAIW, I think it has the same thermistor as the CTS, and yet it lives a much more sheltered life. Regarding the distributor pickup: If you've got spark, it's working fine. Apparently the biggest problem with the distributor pickup is setting the gap correctly. Some rebuilds have too wide a gap. Worse, some rebuilds come back with a bent shaft that wobbles and yields an inconsistent gap. Reason to believe your ignition is working fine: You're getting the "noid" flashes once per rotation, right? Without the ignition firing (which requires triggering by the distributor pickup), the ECU wouldn't count and wouldn't inject. As RPMs increase, the distributor pickup should put out a cleaner, higher-voltage signal, so if the pickup works well enough when you're cranking, it should work even better when the engine is actually running.

Regarding the sour cream test: That would actually be an appropriate post-Thanksgiving variant. Well done!

A worse problem spot than the pigtails, IMO, is the (very likely) crusty and half-rotted Bosch-style connector that mates to the spanking new coolant temp sensor. It takes quite a lot of abuse up there at the front of the engine. The connectors on my thermo housing sensors were in crumble-in-your-fingers condition, with a lovely green patina on what was left of the metal bits. Replacements are plentiful enough. Check out this ebay auction for a complete EFI harness connector replacement kit! Woohoo! A10B1F1 Datsun L6 Wire Harness Connectors Repair Kit afm TPS Fuel Injectors | eBay And I've bought the two-pin connectors from this guy, who is an upstanding gent: Injector Connector Kit 6pc Datsun 280z 280ZX 300zx | eBay There would be no reason I can think of for the injection pulse to be very long (bright flash) and then drop to very short (dim flash), OTHER THAN an intermittent open circuit on the CTS circuit. Well, either that or the ECU is bad. My vote would be for the bad connection.

Well, that's the thing about any car that's reached a certain age, whether a collectable car or not: It holds its value. That doesn't mean it won't deteriorate, and you do have to keep up with inevitable deterioration. However, it won't depreciate, and it may even appreciate if it's a car like a 240 or 280. We bought a '94 Miata a few years ago for $4000, we've enjoyed it, and we could sell it today for $4000. The early Miatas are about at their trough in value -- old enough to be old, but only beginning to be a tiny bit collectible. The 240Z and 280Z are a bit farther along on that curve. This is in contrast with my '92 Saturn, which doesn't have the same collectible potential. It continues to decline very slowly in value, being worth essentially whatever an old, well-running car will bring.

It's quite possible your cold start valve is stuck open, either because it's jammed up or because the thermotime switch isn't working properly. That could be the source of your eye-stingingly rich mixture. (Pinch off the hose to see if the engine runs better.) Also check the throttle position switch for proper operation and adjustment. You might be getting WOT enrichment, which still wouldn't account for eye-stinging richness, though. Finally, you might run some Chemtool B12 through the system to clean up all the injectors. Maybe they're sluggish?

Looks like a well laid out GUI! Very exciting! So I saw a pic of a flaming red pickup in your photo stream. I'm hoping that's not how your Hellfire board got its name! So Tomo, why is a chip called a chip?

+2. Yeah, the coolant temp sensor is THAT important. With an open circuit, the engine will be blowing thick, black smoke out the tailpipe. The reason the "noid" bulbs flash very brightly is that the injector pulse is very long. This usually indicates a CTS open circuit. I would suggest you measure the CTS resistance from the ECU connector, as that will confirm that all your connections are also good. As Lenny points out, there are no diagnostic capabilities. The ECU actually has analog circuitry, not digital! So the way you get data from this EFI system is with a multimeter and/or oscilloscope.

Wow, fantastic! You're not out of the tunnel yet, but at least you can see some light. And yes, a red ground wire.... Hmmmm.... What could go wrong? Giving the PO the benefit of the doubt, perhaps something besides the ground miswiring kept the engine from starting/running after setting up. Then one of the other three mechanics screwed up the wiring -- probably the first one. Anyway, it sounds like you'll have it running in short order. Now we're beyond the weird modifications made by gremlins, and it's just a matter of trading down component failures.

RCB, "DIP" stands for Dual Inline Pins. The black,rectangular integrated circuits you're probably most used to seeing, with pins on each side, some looking a bit like caterpillars, are DIP. The problem with the boards I've seen is that they have the ICs packaged in tiny little cans (with oil!) and wires coming out the bottom like some spider from Fukushima. There's no telling anything about what's inside the can! But give me a DIP IC, and I at least have a few clues, if not possibly off-the-shelf part numbers.

Well... If there is discontinuity between 72 and GND, it should read +12, and grounding 72 would result in current flow. But perhaps we're talking about a lot more current flow than normal. I think Lenny's theory about the red GND wire is plausible. I was shaking my head about that color code in the color schematic.

Nooooo! The Z doesn't need a small-block V8! The L28 is a beautiful engine. You'll see. But of course I'm a sucker for a nice inline-six.

Hey Lenny, I didn't know there were ECUs with DIP ICs in them! Where there's a DIP IC, there's hope. The nice thing about linear ICs is that there are not really that many different pinout configurations, and they are quite substitutable. If I were a purist, I would probably want a reverse-engineered reproduction DIP ECU board with all of the OEM equipment intact. However, I'm not a purist, so I think I greatly prefer your Hellfire board, especially considering the availability of essential fuel-conserving technologies such as lambda feedback. Very exciting, Lenny!

Andrew, I agree about the charm of the Z's buzzer. It sounds very much like a hangover from the Cold War, along with the big, hunkin' "seat belt" light that flashes with it. I kept mine intact for a very long time, smiling whenever it would buzz. But eventually I got tired of listening to it. I disconnected it, just as I've done with almost every other door chime I've ever had. However, it's still there under the dash, just waiting to be plugged back in for a trip down memory lane. Maybe I should put a switch under the dash to turn it off and on, depending on my mood.

Outstanding! Congratulations to you and your son!

Very, very exciting, Len! That's a nice looking board! There's not much I can contribute at this point, except my enthusiasm and my willingness to offer up my Z as one of your guinea pigs. Perhaps also I can give you a chuckle: One of my whimsical pipe dreams is to build a vacuum-tube-based EFI for a vacuum-tube era car. It would be a period-correct "what if they had done this" sort of project. I would of course find some way to showcase the glowing array of tube circuitry in a plexiglass housing, almost certainly with magic eyes to indicate things like mass airflow! But seriously, if you hadn't come along with your digital ZFuel board, I might have eventually designed/built an analog system using socketed, standard, off-the-shelf op amps. Weird, yes... but no weirder than the L-Jet systems we already have.

You're quite welcome, JR! I think once you get this Z running, you will fall in love with it and have to own one yourself.

<<< You can stop worrying about check valve availability. I got everyone covered. >>> Outstanding!

Sounds promising! I have no idea how literal the schematic is, but if you take it at face value, the ground runs all the way back to the battery and is the same branching ground system that grounds the ECU. That could be your smoking gun right there. I'd first check the connections off the battery for obvious reasons. However, the branched connections in the wiring harness are crimped and wrapped over and are possibly also subject to corrosion. You might want to unwrap the wiring harness enough to find all these branch points and verify they are clean/good. Don't worry about the fact that 12V will blow a bulb. A straight 12V will melt down an injector the same way. Remember that you have drop resistors wired in series to limit the current flow! Just use a single bulb, and you'll be fine. Have a great Thanksgiving, JR!

JR, the Xmas bulbs are normally strung in a long series. They typically glow with maybe 3V across them. They definitely work, but I admit they're not as refined as real "noids." When the key is in the ON/IGN position, the fuel injection relay should connect from +12 to the common sides of the two gangs of drop resistors. The other side of each drop resistor leads to one side of each injector. The ECU grounds the other side to deliver a pulse of fuel. When an injector isn't grounded, you should read 12V across both leads of the injector. Regarding the fuel pump relay vs. the ECU: Yes, '76 appears to be different. I'm looking at a color schematic for the '76 at this link: http://www.4moores.com/280z/files/test_76_280z_wiring%20copy.jpg It seems the fuel pump relay is part of the electronic fuel injection relay in that year (hence my confusion). There's indeed an input to this relay from pin20 of the ECU. HOWEVER, this input is internal to the relay and would appear to play some role in "keeping" the contact after it is initially "made" via input from 76 (+12 "START"). Pins 20 and 10 are the +12 supply to the ECU. Pin 43 feeds +12 to the drop resistors. So although there is connectivity between the fuel pump relay and the ECU, it's only because the fuel pump relay is part of the EFI relay. In other words, the "logic" of the ECU isn't responsible for actuating the pump, if that makes sense. It's interesting you say that you get a running fuel pump when you introduce ground to the circuit. Are you saying it's when you ground 72 of the relay? If so, that would indicate you have an open ground. To be clear, the relay should be actuated when you introduce +12 to 47 ("START"). The ground should be continuous.