280zedx Posted June 6, 2004 Share Posted June 6, 2004 step by step...the supercharged L28 is coming together. i want to get the MS up and running before i move onto the MS&S setup. the latest frustration and conclusion after 12 hours of wiring and testing- It seems that it's not getting a good tach signal. Anybody with a non-turbo (variable reluctor dist.) have this problem as well? so far: -all the standard MS tests (spark, fuel, TPS, MAP, base settings, etc) were thoughally checked and working fine -The priming pulse width seems to be working, if i give it a couple shots, then try it, the car will fire up then die right away. -there is the very odd "flicker" of life (100 to 400 rpm) on the Megatune while we were testing and cranking. I'm assuming it is firing up on the residual fuel from the priming pulse, but since it's not seeing a good tach signal, then it shut's down. My electronic guru, Jeff, will try a few capacitor changes to help clean up the signal, and next testing night we should probably try a shielded cable as well. My big question: does it sound like i need a MSD type of amplifier/conditioner? or should i make matters worse and experiment with the MS&S at the same time. (remember: non-turbo distributor) thanks, Mike (1983 280zx soon-to-be-on-the-road supercharged L28) Quote Link to comment Share on other sites More sharing options...
mobythevan Posted June 6, 2004 Share Posted June 6, 2004 Are you pulling the tach signal from the positive coil terminal or from the distributor wires? From the coil is the typical way people do it for non-turbo setups. If you are pulling straigth from the distributor then you may need a signal amplifier. Quote Link to comment Share on other sites More sharing options...
Tony D Posted June 6, 2004 Share Posted June 6, 2004 showing NO tach activity? I would check connections, the VR should privide a good enough firing signal through the amplifier... Like Moby said, off the coil terminal, though. If not, you can trigger like above in the sticky diagram. Is the tach in the car connected and functioning? Origianally I had a problem with incompatible voltage regulators, and once I installed the proper voltage regulator I regained my in-dash tach, and could also get the MSS to fire when it should. Something in the Tach/VR circuit drew dow nthe firing impulses for the coil and it would only fire every third cylinder or so. When disconnected from the alt and VR, running off the battery the thing worked great. Took a while to figure out the internal/external regulator incompatibility and that it actually affected the spark trigger signal, though... Quote Link to comment Share on other sites More sharing options...
280zedx Posted June 6, 2004 Author Share Posted June 6, 2004 i'm taking the signal off the coil "-". Moby are you telling me it should be the "+"????? The car was running fine before the MS swap so i can assume the zx components are good. Connections were tested completely and there is a signal getting to the MS, just how much and how well is hard to tell without a scope. Tony, are you running your MSS like the sticky diagram? thanks for the added info on regulation, i'll keep that in mind. I'm tempted to go shopping for the HEIs for the full MSS and work on that at the same time...it's not running now so i have nothing to lose.LOL. I just hope i'm not in over my head already. Quote Link to comment Share on other sites More sharing options...
z-ya Posted June 7, 2004 Share Posted June 7, 2004 Try installing the "Dave" cap mod. It worked for me. I was having problems with noise on the tach signal. And yes, you should connect the tach signal to the "-" terminal of the coil. Pete Quote Link to comment Share on other sites More sharing options...
sims76 Posted June 7, 2004 Share Posted June 7, 2004 Using an HEI module as an ignition amplifier might be an inexpensive way to find out if this is your problem. I was unable to get a good signal with any of the MS tach mods. Right now, I'm using a MSD unit as the trigger. For MSnS, I'm going to use an HEI as the trigger/amplifier, and MSD to deliver the spark. Good luck, this is a very frustrating part of the install. http://www.sherco-auto.com/ignition.htm Quote Link to comment Share on other sites More sharing options...
mobythevan Posted June 7, 2004 Share Posted June 7, 2004 i'm taking the signal off the coil "-". Moby are you telling me it should be the "+"????? Sorry, I just wanted to see if you were taking from the coil or the distributor directly. I never used the coil method so I forgot which terminal it pulls from, I didn't even think because coil + would be 12v all the time, wouldn't work very good as a trigger. Quote Link to comment Share on other sites More sharing options...
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