AK-Z Posted May 1, 2008 Share Posted May 1, 2008 I have a question on the stock EFI system. Is injector firing on these batch or sequential? Reason I (I know, not L6 engine) want to wire a KA24DE to the stock 280Z efi system, because its what I have, and I just want to get it running. For the dizzy, I tapped the and added a terminal for the coil so I can just totally bypass the circuitry (I know, not advance/retard, I'll deal with it later), so I"ll have to deal with spark separately from the EFI system. If The stock EFI is sequential, would I be able to due batch firing by connecting all the wires together respectedly? It does fire by timing of a spark event, correct? Any other suggestions? Issues that might arise? Admins, feel free to move this to the appropriate sub thread, if needed. Quote Link to comment Share on other sites More sharing options...
Administrators RTz Posted May 1, 2008 Administrators Share Posted May 1, 2008 I have a question on the stock EFI system. Is injector firing on these batch or sequential? Stock is batch fire. I'm guessing, back in '75, sequential was some engineers wet dream. Any other suggestions? Issues that might arise? I think you're about pull the trigger on a shotgun... aimed at your foot. Quote Link to comment Share on other sites More sharing options...
AK-Z Posted May 1, 2008 Author Share Posted May 1, 2008 I think you're about pull the trigger on a shotgun... aimed at your foot. Thanks constable. How so? I just need it to run. Nothing performance oriented. Only issue that I see that might be an issue is spark dwell. All it needs is air, fuel, spark and oil, right? Quote Link to comment Share on other sites More sharing options...
Administrators RTz Posted May 2, 2008 Administrators Share Posted May 2, 2008 All it needs is air, fuel, spark and oil, right? Don't forget quantity. Find two dyno sheets of a stock L28 and one of a KA. Take a look at the torque curve. Not the 'value', but rather the 'shape'. Completely different. This shape represents the VE curve of the engine. The L28 L-jet is tuned for a much flatter curve. Short version? You're AFR's will be 'unusable' through a significant portion of the curve. Run? Yes. Drivable? Not by my definition. Furthur, locked timing would be wretched on the street, in my opinion. Keep in mind, this stuff doesn't just reduce power. It also has the potential to shorten engine life, sometimes significantly. Only issue that I see that might be an issue is spark dwell. Dwell is handled by the ignition module. The ECU knows not/cares not about dwell. For the dizzy, I tapped the and added a terminal for the coil so I can just totally bypass the circuitry (I know, not advance/retard, I'll deal with it later), so I"ll have to deal with spark separately from the EFI system. I do not understand the above. The ECU is looking for 6 evenly spaced pulses from a VR sensor. Are you providing that to the ECU? I'm left thinking your plan is very temporary. What is the long term plan? Why not do that first? Moving to Fuel Delivery... Quote Link to comment Share on other sites More sharing options...
AK-Z Posted May 2, 2008 Author Share Posted May 2, 2008 Dwell is handled by the ignition module. The ECU knows not/cares not about dwell. KA its handled by the ECM. thus internal coil in the dizzy as well as internal CAS (which I don't have the connectors to). I do not understand the above. explained above. The ECU is looking for 6 evenly spaced pulses from a VR sensor. Are you providing that to the ECU? If its batch injector firing then why is this even needed? it would be the same as running it on a single cylinder and just needs the length of time between each spark event to coordinate fuel curve. I'm left thinking your plan is very temporary. What is the long term plan? Why not do that first? Moving to Fuel Delivery... Just want have it running untill I can source a decent UNMODIFIED wiring harness and ECM. They way I look at it, the whole EFI system on a L28 is to supplement for a carburetor, with very little sensors to run. Quote Link to comment Share on other sites More sharing options...
Daeron Posted May 2, 2008 Share Posted May 2, 2008 supplement or no, it might spin over but you are risking your engine, especially if you actually try to drive it under load like this. Remember, you are asking a 30 year old computer to do these things.. the only reason it even works on the L28 is because the tasks were very rigidly defined within a narrow band of functionality. The VE of the KA (like rontyler mentioned) is so utterly different that you are seriously going beyond the boundaries of what the L-series ECU expects and can deliver, as far as fuel, air and spark demands are concerned. The theory behind your setup is not entirely flawed; but it is more flawed than you might think. What makes you so urgent to run this engine before you have all the parts to it? In a fuel-injected vehicle, the ECU and associated sensors, etc are as integral as the intake manifold is to either an FI vehicle or a carbureted vehicle. Maybe the manifold from the BMW will fit on the RB.. but maybe not.... Quote Link to comment Share on other sites More sharing options...
Administrators RTz Posted May 2, 2008 Administrators Share Posted May 2, 2008 If its batch injector firing then why is this even needed? it would be the same as running it on a single cylinder and just needs the length of time between each spark event to coordinate fuel curve. Batch-fire injects half the needed fuel every crankshaft revolution. It knows one revolution has occurred when three ignition events have occured, and that happens when three teeth pass the VR. See the problem? Just want have it running untill I can source a decent UNMODIFIED wiring harness and ECM. I'm certain you'll be much happier with the results if you source those items first. Quote Link to comment Share on other sites More sharing options...
Administrators RTz Posted May 2, 2008 Administrators Share Posted May 2, 2008 In my haste, I left out a couple details in my second post in effort to simplify my point. Let me clarify... There are 6 'teeth' in the distributor that pass by a VR sensor. The VR sends this 'event information' on to the ignition module. The module process's this signal, charges, and then fires the coil via its neg. terminal. The ECU is also connected to the coil neg. terminal. This provides RPM information to the ECU. The ECU knows every third 'pulse' equals one revolution, and injects 1/2 the amount of needed fuel. There are many challenges in meeting your goals. It's not worth the hassle, in my opinion... there are easier way's to skin your cat. Quote Link to comment Share on other sites More sharing options...
AK-Z Posted May 2, 2008 Author Share Posted May 2, 2008 Sigh. I just might as well try to carb it then. Think I'll have spark issues with it? Inless someone has a harness and ecm. Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted May 2, 2008 Administrators Share Posted May 2, 2008 The old Datsun L-jet can not read a CAS. Unless you plan to totally simulate the 6 cylinder ignition system with the 3 firings per crank revolution, including a coil and way to disperse that hight tension electrical energy, it will not run on the 4 cylinder. As Ron already mentioned, the VE curves are SO different it will wont be drivable on the street. You might be able to get it to idle, but to drive it? I don't think so. Just throwing a cam in an L-6 which only alters the VE slightly makes so much change, and the factory EFI has flat spots in various parts of the of the power band because it can't deal with the altered VE curve. The KA is even SO much more different. Remove the boot between your AFM and Throttle body on your Z car and drive it. That is approx how the KA would run with the Z car EFI, and that is after you went through the trouble to totally simulate/duplicate the 6 cylinder ignition system on 4 cylinder, which will still need a 4 cylinder ignition system to fire the spark plugs. Sounds like a lot of work for something that still wont work, huh. That is our point. In getting the L-jet 6 cylinder system to work on any 4 cylinder, the shooting one self in the foot is probably the best analogy. You would be much farther ahead just getting a Megasquirt system and doing it right. Or as you mentioned, carburetion. Carburetion would MUCH more drivable, even if you just through on a Holley double pumper! Sigh. I just might as well try to carb it then. Think I'll have spark issues with it? Inless someone has a harness and ecm. You will have spark issues “then?!?!” You’ll have the exact same spark issues with carbs as with the Z car EFI. The Z car EFI ECU does not control the spark in any manner. the Z cars ignition system is completely standalone and independent of the EFI. The EFI only reads the spark from the negative side of the coil, waits for the third spark to occur and then fires the injectors. That is the only link the Datsun EFI has to the ignition system. Again, Mega-Squirt would answer ALL your issues, giving you precise control over your fuel, and Mega Squirt will even CONTROL/RUN your ignition as well, distributor and distributor-less ignition. Quote Link to comment Share on other sites More sharing options...
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