Is The 280Z Fuel Injection a "Good" System?

[Captain Obvious]

For the ECU, I would personally like to have it work like the analog design,to keep it in the spirit of the original designs, although a simple microprocessor would probably help to make up for certain things.

I'm with ya. I wouldn't mind having a drop in replacement for the ECU that is digital at the core instead of the current analog design. From the outside, it would appear to work pretty much the same as stock, but just better tuned, and more consistent. Famous last words, but I don't think it would be that difficult. I haven't really thought about how many A/D's you would need, but I bet there's a micro available with enough on board.

As for the cost of building an analog ECU from scratch using the TR-7 schematic... Wow. A one off? You don't want to know. You don't even want to think about it. :pirate:

I would guess hundreds if you have contacts in the industry. Over a thousand if you don't?

And then there's no way you would be able to tune it. You know why there are resistors soldered in parallel on the stock ECM's? Because that's how the factory characterized and tuned the behavior. They probed points on the board under power and then tweaked the resistor values until they got what they wanted.

[TomoHawk]

Somebody has to ask... And there's always the prototype to any mass-produced device. l'll bet a good EE would figure out a few places where you could put some adjust ability...

Edited January 18, 2013 by TomoHawk

[Captain Obvious]

Haha! Yeah, but the prototype for this one occurred in 1973 or 74. The mass production is already over and long gone. You're thinking there might be a market for analog replacements for the stock analog ECU? With the digital options available already, I think that would be a hard sell.

I'm not sure what you mean with the comment about adjustability. Are you wishing for a way to tweak the original analog ECU?

[TomoHawk]

There is just a little room for tweaking the ECU, but there is more potential to improve the efficiency (and maybe the power) of the engine by adding one or two more things (like an oxygen sensor.) I'm not looking for miracles, but eventually our L28s will be expensive doorstops when the supply of working, stock ECUs runs out. You will either have to change the ECU, or the engine.

Edited January 18, 2013 by TomoHawk

[Captain Obvious]

Or for people who are allowed to... Change to carbs.

I've got a great set of flat tops sitting all lonely in a box in the garage,

[MotoManMike]

1000 hours? Do you speed read?

Exactly

[240260280z]

Hmmmm TR-7 ECU in a Z....wish I had time

[TomoHawk]

Remember... It's really just an L-Jetronic ECU.

The TR7 came out in 1975. Assuming it had the L-Jet ECU in it, it would precede the 1976 L28e, and the L28e's ECU could be called a slightly modified TR7 ECU.

But then again, maybe you actually could swap them.

Edited January 18, 2013 by TomoHawk

[FastWoman]

Tomo, FAIW, there's not enough information in the TR7 schematic to duplicate its ECU, unless you happen to have a source of supply of the proprietary ICs (big, black rectangles on the schematic with many, many connections each). Those ICs are little black boxes, so to speak.

I suspect an EFI system could be retrofitted that uses an air flow meter or MAF sensor and controls a 6 cyl engine (either inline or V), provided the same injector flow rate is used, and provided it has a vacuum-regulated fuel pressure regulator. I think that would remove all the mystery variables, such as the air flow properties of a different intake manifold.

Then again, a MegaSquirt system would seem the obvious way to go, if someone would only build/preprogram a drop-in replacement (wired into the same ECU box) that would use the same sensors (including the AFM). That would preserve the vintage Rube Goldberg look and feel of the L-Jet system, while introducing digital reliability.

[TomoHawk]

No, the TR7 schematic can't be converted directly to a PC board, but with it and what we know enough about L-Jetronic Fuel Injection theory we can fill in for any "little black boxes" Considering the simplicity of L-Jetronic fuel injection, it doesn't take a lot of engineering to duplicate things, using some digital components, what was done using the more complicated analog stuff. Take the FM radio receivers you get at the Dollar store- in that little plastic box, you get a FM radio receiver, digital frequency display and audio amplifier, plus a few buttons to control the tiny, simple microprocessor inside. Substituting a few modern parts, like an MAF sensor, oxygen sensor, or AFM for the deprecated stuff we now use, would probably improve the control and make the system more reliable, with spare parts available for another 30 or 40 years.

A 280Z ECU doesn't have to be "programmable" as we are accustomed to the few adjustments that are available, but there is room for a few adjustments.

[Captain Obvious]

TomoHawk, I believe you underestimate the amount of effort required to reverse engineer the original schematic when there are custom undocumented IC's in the mix. There's no way I could fill in for the "little black boxes" without lots and lots and lots of effort. Maybe never...

It might appear "simple" from the outside, but I bet there's a lot of black magic in that old analog L-Jet box.

In fact, I think it would be a much easier job to build a new system using a digital core that "reacts identically to input stimuli" than trying to figure out how the original analog system does it.

[Captain Obvious]

if someone would only build/preprogram a drop-in replacement (wired into the same ECU box) that would use the same sensors (including the AFM). That would preserve the vintage Rube Goldberg look and feel of the L-Jet system, while introducing digital reliability.

Fastwoman, I think that's what Tomohawk suggested earlier, and I agree. I think that would be cool.

I've got the output stage under control, and I'll take care of the power supply. What section do you want to do?