Conversion to EFI from Carb

[Mike]

Hi guys,

Ok, so I'm looking at a project this year. My car is fully restored and I've got triple Mikuni's installed. It's a great system, but, just coughs and sputters a bit too much for me. I have a full EFI system out of a 78 280z including computer and intake with brand new injectors. Does anyone have a tech article on making the swap happen? That said, is it possible to use my existing fuel supply piping and fuel tank (I've got a '71)?

Mike

[cozye]

If I were going to go through the trouble of converting to efi, I wouldnt use the oem Bosch system. It's not a great efi setup. Would be just as easy to do a custom efii setup using a mega squirt ecu, map sensor, and ideally o2 sensor. The 280z system is not tunable, it's ugly, and it doesn't age well. Many 280 owners get rid of it. Seeing that you have a 240 I would think that the 280 ecu will not be tuned properly for your motor and since it doesn't use any sensors to adjust air fuel mixture, I'd say it won't work well

You could use the injectors and manifold though, so all is not lost

[Zed Head]

I have a functional EFI system on an engine on a stand in the garage. You need the EFI harness from the engine bay to go along with the ECU, to make it easy. A few wires need to be jumped or have switched power run to drive the ECU and the injectors, but it's not too difficult to figure out from the FSM wiring diagrams. One key piece that is needed though is the resistor from the cabin that's on the "blue wire" circuit to Pin 1 and the tachometer. I think that it "conditions" the signal to the ECU. Without it the ECU won't fire the injectors correctly. If I recall, it's about 2.6 Kohms, maybe.

Check Hybridz for the turbo swap in to 240Z to see what people do for fuel supply. Many run a new supply line and use the original supply line as the return. Apparently the EFI fuel pumps flow too much fuel to use the original 240Z lines and will back up, causing uncontrollable high pressure.

But, as cozye says, to make it run well, you'll need to get in to tuning and modifying and it might be a pain.

[rcb280z]

Hell, the stock system is a PITA. Just read my thread "EFI relay unplugged" and you'll see the problems I'm having! If I could I would take it all out and install an aftermarket system like Megasquirt or something I would. Don't know if it would pass the visual inspection in CA.

[Bruce Palmer]

Hell, the stock system is a PITA. Just read my thread "EFI relay unplugged" and you'll see the problems I'm having! If I could I would take it all out and install an aftermarket system like Megasquirt or something I would. Don't know if it would pass the visual inspection in CA.

Therein lies why the EFI to SU carb swap is such a nice piece of business for us. On top of the limitations of the early FI system, they arfen't getting any fresher with age.

[madkaw]

Mike,

i'm going to be doing the same thing someday-going to FI from carbs, but I wouldn't go through all that work to put such an outdated system on there.

Look at it as a long term project and do it a little at a time. I plan on getting a megasquirt set-up and start off using my LC-1 and programing my spark control first. You can hook up your MAP sensor and get used to seeing things on your laptop as how your engine runs.

There's less parts and less things to screw up with a newer programmable ECU system. You would also be taking a performance penalty running a stock EFI system. You could still use the stock manifold and throttle body, injectors to save some money, but I wouldn't transfer anything else-IMHO

i

i

[cozye]

Therein lies why the EFI to SU carb swap is such a nice piece of business for us. On top of the limitations of the early FI system, they arfen't getting any fresher with age.

You guys offer a package for that?

[240260280z]

You just need one of these:

[sblake01]

@Bruce: As many times as you and I have needled each other (no pun intended) about the Old School EFI to SU thing over the years I wouldn't ever consider doing SU to EFI unless it was some type of modern EFI. Though I had some success with it, the old JECS system is tough enough to sort out as it was originally installed but a retrofit?????:tapemouth:ermm:

[Bruce Palmer]

You guys offer a package for that?

Yep, we can do 'em here or ship the pieces. unhook the FI harness and put in a low pressure fuel pump. From there it's a bolt on.

[Bruce Palmer]

@Bruce: As many times as you and I have needled each other (no pun intended) about the Old School EFI to SU thing over the years I wouldn't ever consider doing SU to EFI unless it was some type of modern EFI. Though I had some success with it, the old JECS system is tough enough to sort out as it was originally installed but a retrofit?????:tapemouth:ermm:

Stephen,

I equate the early FI system to the flat top carbs. Both had shortcomings when new and neither has gotten any better with age. Talking to Steve on the subject, the second gen EFI from the Z was a much better system.

[cozye]

Yep, we can do 'em here or ship the pieces. unhook the FI harness and put in a low pressure fuel pump. From there it's a bolt on.

Awesome Bruce. If I didn't have a rebuild in mind with triples, I highly consider this. I sorted my efi out where it runs good now, but Ive sourced another l28 with n42 head and I'm thinking of a mild build with it for a next winter project