csm240z Posted June 28, 2010 Share Posted June 28, 2010 I'm at an end trying to figure out what has been causing this so maybe you can help. I'm not extremely savvy car wise. This is kind of a learning experience for me. But I had the car (72 240z L28et w/ megasquirt and EDIS) running fine and tuning the idle. Then I quit for the day, tried starting it up and it was hesitant. Once it finally did it was running really rough and seemed to be misfiring. I've gone through everything trying to figure out what is causing it, I get spark on all the plugs, injectors are all good, swapped EDIS and coilpacks, reloaded firmware on megasquirt, changed battery and alternator. Like I said it almost sounds like a misfire and when I pull the plug on one of the two middle cylinders it smooths out like it was running before...the only thing I can think of is that the head gasket is blown between the two and when one ignites it lights the other...but then again I have no clue and would like to steer away from pulling the head right now. Would appreciate your help Quote Link to comment Share on other sites More sharing options...
Tony D Posted June 30, 2010 Share Posted June 30, 2010 is your edis firing order correct? Quote Link to comment Share on other sites More sharing options...
woldson Posted June 30, 2010 Share Posted June 30, 2010 Dose not edis fire all cylinders everytime? Hence the wasted spark? Ive read much on edis and if somehow I missed something, I might as well learn it now. Quote Link to comment Share on other sites More sharing options...
stony Posted June 30, 2010 Share Posted June 30, 2010 (edited) A wasted spark is when in an ignition system in a four-stroke cycle internal combustion engine spark plugs fire in pairs, on both the exhaust and compression strokes. The extra spark on the exhaust stroke has no effect and is thus "wasted". This design is simpler than a conventional ignition system, but the extra sparks can reduce the lifespan of components (contact breaker, spark plugs). If your firing order is off you will have issues. BTW i couldn't put that in my own words so i pulled it from wiki Edited June 30, 2010 by stony Quote Link to comment Share on other sites More sharing options...
Zmanco Posted June 30, 2010 Share Posted June 30, 2010 An EDIS coil pack for our L6 actually has 3 coils in it. Each coil fires 2 plugs which are matched to the pairs of pistons that move in sync. Stony is correct that each pair is fired at the same time for simplicity, but only one cylinder will have any air/fuel and hence make power. The other is wasted. To the OP, I would double and triple check that you have the plug wires attached correctly. From what you describe, that's most likely culprit. Quote Link to comment Share on other sites More sharing options...
csm240z Posted July 1, 2010 Author Share Posted July 1, 2010 I am fairly certain they are but will double check either way. The two middle cylinders are on the same coil pack and when i pull either of those it runs perfect. Any other ideas in the mean time? Quote Link to comment Share on other sites More sharing options...
woldson Posted July 1, 2010 Share Posted July 1, 2010 Even if the thier are 3 coil packs, since they are firing on a ext/comp stroke then you would have all cyl fireing all the time? Maybe Im being dense. Anyhoo, possible emf from a wire on the two center holes. Feild becomes too great? Spark plug that has become to resistive? (causing bleed to ground) Quote Link to comment Share on other sites More sharing options...
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