Eric2015 Posted December 27, 2014 Share Posted December 27, 2014 I'm in the middle of swapping the L28ET into my Datsun 280Z. The computer does have power. I'm using a GM 4 Pin HEI. I have a diagram below showing how I have it wired up. There are two Yellow/White wires coming from the computer. One needs to go to the HEI. I've tried both and no spark either time. I'm using the stock coil from the original naturally aspirated 280Z engine. This shouldn't be a problem should it? Also on the passenger side of the cab, underneath the dash, is a box that reads: Transistor Ign. Is this part of the Ignition system? Hopefully you guys can point out something that I don't have wired up right. If not I might try replacing the CAS. Thanks Quote Link to comment Share on other sites More sharing options...
NewZed Posted December 27, 2014 Share Posted December 27, 2014 Disconnect the stock Transistor Ign. at the module, not at the coil. Otherwise the HEI module may not be able to break the circuit to get a spark. That's one possibility. It's possible to test the ECU output also. The yellow/white wire should have off-on voltage when the engine is turning, if it's getting a good CAS signal. People have also described ways to test the CAS. Quote Link to comment Share on other sites More sharing options...
Eric2015 Posted December 27, 2014 Author Share Posted December 27, 2014 Disconnected the Transistor Ign. Also tested the ECU output. No voltage on either of the yellow/white wires. I'm assuming I should go ahead and replace the CAS sensor? Quote Link to comment Share on other sites More sharing options...
cgsheen Posted December 27, 2014 Share Posted December 27, 2014 I've never had any luck testing the ECU "signal to fire" with the crappy multimeters I use. I never get a voltage reading - it happens too fast - I think you'd need an oscilloscope. "There are two yellow/white wires coming from the computer" - The Yellow/White you're looking for comes from ECU pin 5 and only runs a short way to a connector under the dash in the stock harness. The 1982 280ZX FSM shows the wiring (without colors unfortunately) and how the ECU connectors and pins are laid out in the "Engine Fuel & Emission Control" section: EF&EC-96 . You don't need colors, just match the connector, it's clip, and double check your "orientation" with the missing pins (spaces with no wires) in the diagram... You'll find "pin 5" right away. (outermost two-row clip, pins 1-10 are on the clip side, pin 1 has no wire, pin 3 has no wire, pin 5 is right by the clip, pin 7 has no wire) You can test the CAS, but if you already have a replacement, you may as well swap it out. Be sure to test your components AND the wiring back to the ECU. You can pull the plug out of the distributor and test voltage (with IGN ON) and GND (red and black to the 4-pin plug). Also check continuity of the Green and White wires back to the ECU (they change colors in the ECCS harness) but one goes back to pin 8 and one to pin 17 - use the above diagram. Double check your HEI wiring. It's nearly as simple as the original coil/ignitor. It needs power and GND. It has a signal input from the ECU and an output to the coil "-". Disconnect the stock Blue wire to the coil "-" terminal until you have spark and/or the engine running. Remember that the GND on the HEI is actually the body (and bolt holes). Make sure the Black/White to the "+" coil (and thus the HEI) has power at IGN ON. Check and clean all the connectors in the harness. Most ECCS problems turn out to be electrical - wiring and connectors... Have fun! Quote Link to comment Share on other sites More sharing options...
NewZed Posted December 27, 2014 Share Posted December 27, 2014 I wonder if the Hertz or Tachometer function on a meter could do the sensing and counting. If I had a turbo EMS and was troubleshooting I think that I'd probe the various connections using one of those, with everything plugged in and connected. I've used the Hertz function to measure coil pulses, as a pseudo-tachometer. One side on the coil negative, the other to ground. Might work the same on the CAS and/or ECU output. The OP didn't say what kind of CAS he's working with. Apparently, the 81's are generally problematic. Quote Link to comment Share on other sites More sharing options...
Eric2015 Posted December 28, 2014 Author Share Posted December 28, 2014 Good news, I've made progress. I did find the exact yellow/white wire I needed. It was very obvious once you described it haha. So I threw the distributor back together. I then tested the my computer power wire and was losing power when cranking. So I switched it to a different spot and have power while cranking now. I then disconnected the the blue wire from the coil. The HEI is wired in correctly. The zip tie in the picture is just the hold it in place. It's grounded through the bolt holes. The coil also has power. After all of this, I finally got spark. But the car still won't start. The spark doesn't seem like its very strong. I test the spark using the screw driver method. On most vehicles I test it's a strong and fast spark. Like spark spark spark spark really fast. That was not the case with this. It was more like spark....spark....spark....spark. I'm not sure if that's just how it is on this engines or what. I also decided to check the fuel pressure in case maybe that was the issue. My fuel pressure gauge leaks a tiny bit so I can't get an exact reading. But the gauge was reading over 20psi. So after you consider the loss it has somewhere between 20 and 30psi. That's about what these pumps run right? So that's as far as I got for tonight. Any ideas now? Maybe something to do with the injectors? Quote Link to comment Share on other sites More sharing options...
Eric2015 Posted December 28, 2014 Author Share Posted December 28, 2014 Or maybe the timing is off.... I should check that Quote Link to comment Share on other sites More sharing options...
cgsheen Posted December 28, 2014 Share Posted December 28, 2014 If the engine is not running your fuel pressure should be around 36 PSI. When running it'll drop with (by) the amount of vacuum in the intake manifold. (the FPR is supposed to maintain a 36.3 PSI pressure differential between the fuel rail and intake manifold. If you have 10 PSI manifold vacuum, you should see 26 PSI in the rail - if you're boosting 5 PSI, you should see 41 PSI...) You weren't clear about where you were testing spark. At the plug? But, ya, you should check timing. Then make sure you're getting fuel. You can try starting fluid... Quote Link to comment Share on other sites More sharing options...
Eric2015 Posted December 28, 2014 Author Share Posted December 28, 2014 I tested spark at the coil and at the plug. I tested the spark again today and I'm pretty sure its getting a strong enough spark to ignite. I'll try starting fluid and if that doesn't work I'll check the timing Quote Link to comment Share on other sites More sharing options...
NewZed Posted December 28, 2014 Share Posted December 28, 2014 If it's been sitting for long you could have dry cylinders. Low CR plus poor sealing plus old fuel = hard start. Squirt some oil in the cylinders. You might also look through the service manual. You don't seem to know the basic numbers for the system, like fuel pressure. There are tests described also for determining if your injectors are operating. Plus 30 pages of troubleshooting chart. EFEC chapter, ECCS system. http://www.nicoclub.com/FSM/280z/ Quote Link to comment Share on other sites More sharing options...
Eric2015 Posted December 28, 2014 Author Share Posted December 28, 2014 I'm not sure how long the engine has been sitting. The fuel is fairly fresh though. Only a couple of months old from when it had the original NA 2.8. I tried starting it with starter fluid and still nothing. Thanks for the link! I'll do some reading and try to get to know the L28ET better Quote Link to comment Share on other sites More sharing options...
Tony D Posted December 31, 2014 Share Posted December 31, 2014 (edited) Didn't let that HEI lose ground while you're powered on, or it's toast if you don't have a robust aftermarket unit with current limiting. Stockers fry with the snap of your fingers! Chances are good you weren't "losing power" while cranking, you were getting a pulse and your meter was auto ranging and too slow to catch it. Set it to 20 V or lower manually (5 or 10 ideally) and you should be able to see the pulses from the ECU. If you use a NOID Light or LED of proper voltage it wil "pop pop pop" light on that wire when cranking if you got the polarity for + & - right... Edited December 31, 2014 by Tony D Quote Link to comment Share on other sites More sharing options...
Eric2015 Posted January 9, 2015 Author Share Posted January 9, 2015 So I checked the timing and it should be good enough to start. Then I checked the injectors. I'm not getting any power to the injectors. What could be causing this? Quote Link to comment Share on other sites More sharing options...
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