big-phil Posted November 14, 2007 Share Posted November 14, 2007 This has been a thorn in my side. I've searched over and over. I've wired up several combinations on MS to drive my tach with no luck. I have a Mallory E type coil. It will not work my tack when hooked to the neg side. When I hook up my stock coil my tack works perfect. Also when I hook up an old big yellow Accell super coil my tach works perfect. The problem: The stock coil, and the Accell super coil cut out at high boost (18-20lbs) My Mallory E-coil runs like a champ and the car pulls strong, and smooth. My question: Who has a coil that will support high boost and is hooked to their tach and the tach works perfect? Thats the coil I want to buy. Quote Link to comment Share on other sites More sharing options...
mario_82_ZXT Posted November 14, 2007 Share Posted November 14, 2007 Have you tried adding 6.8k-10k ohm resistance to the tach signal wire? Mario Quote Link to comment Share on other sites More sharing options...
big-phil Posted November 14, 2007 Author Share Posted November 14, 2007 Yes I've tried it all. I even got a 0-50k trim pot and had someone SLOWLY turn it from 0k to 50k Resistance with no luck. If my stock and Acell coil will work the tack, then there has to be one that will support high boost? Quote Link to comment Share on other sites More sharing options...
Forrest Posted November 14, 2007 Share Posted November 14, 2007 Are you using MSD or a Hi-6 to drive your coil? Quote Link to comment Share on other sites More sharing options...
big-phil Posted November 14, 2007 Author Share Posted November 14, 2007 Its ALL megasquirt. Its the internal vb921 chip thats running the coil. I've tried looking up tach adapters but they seem to be for folks using msd? Quote Link to comment Share on other sites More sharing options...
mario_82_ZXT Posted November 14, 2007 Share Posted November 14, 2007 Hmm, you could also use the megasquirt box to drive the tach. Moby has done it on his LS1 MS setup. I think it's a pretty easy mod. http://www.msextra.com/manuals/MS_Extra_Hardware_Manual.htm#tachoout Mario Quote Link to comment Share on other sites More sharing options...
Forrest Posted November 14, 2007 Share Posted November 14, 2007 Mario beat me by a few seconds there...but I've never tried using MS to drive my coil as shown in those diagrams. I'm just running the FIDLE to my MSD box (only option available back when I first set this stuff up.) I was using an aftermarket tach to read the MSD output, but I'm about to try and switch back to the factory tach using the tach adapter. Have you had any problems with the VB921? I read enough posts where people were frying it to make me leery of recommending that route to people. Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted November 14, 2007 Share Posted November 14, 2007 Have you seen this thread? http://forums.hybridz.org/showthread.php?t=123341&highlight=msd+tach I don't know squat about megasquirt, but sounds like all you need is a stronger trigger. So if the MSD part doesn't work perhaps you can contact bryan01 and see about getting the adapter he made. http://store.summitracing.com/partdetail.asp?part=MSD%2D8918&autoview=sku Quote Link to comment Share on other sites More sharing options...
big-phil Posted November 14, 2007 Author Share Posted November 14, 2007 Hmm, you could also use the megasquirt box to drive the tach. Moby has done it on his LS1 MS setup. I think it's a pretty easy mod. http://www.msextra.com/manuals/MS_Extra_Hardware_Manual.htm#tachoout Mario I've tried those:mad: Quote Link to comment Share on other sites More sharing options...
big-phil Posted November 14, 2007 Author Share Posted November 14, 2007 Mario beat me by a few seconds there...but I've never tried using MS to drive my coil as shown in those diagrams. I'm just running the FIDLE to my MSD box (only option available back when I first set this stuff up.) I was using an aftermarket tach to read the MSD output, but I'm about to try and switch back to the factory tach using the tach adapter. Have you had any problems with the VB921? I read enough posts where people were frying it to make me leery of recommending that route to people. I've replaced it but only because I had something set wrong in MS and fried it. Its been running great for a long time now. Quote Link to comment Share on other sites More sharing options...
Thumper Posted November 14, 2007 Share Posted November 14, 2007 I've tried those:mad: Just buy a 5" aftermarket tach and put it in the stock location... It has a faster response rate. Sounds like that might be your only option. I personally used my output from my msd box so can't help. Quote Link to comment Share on other sites More sharing options...
big-phil Posted November 14, 2007 Author Share Posted November 14, 2007 Have you seen this thread? http://forums.hybridz.org/showthread.php?t=123341&highlight=msd+tach I don't know squat about megasquirt, but sounds like all you need is a stronger trigger. So if the MSD part doesn't work perhaps you can contact bryan01 and see about getting the adapter he made. http://store.summitracing.com/partdetail.asp?part=MSD%2D8918&autoview=sku Now this might work. Thanks guys! Quote Link to comment Share on other sites More sharing options...
big-phil Posted November 14, 2007 Author Share Posted November 14, 2007 Just buy a 5" aftermarket tach and put it in the stock location... It has a faster response rate. Sounds like that might be your only option. I personally used my output from my msd box so can't help. I want to keep the stock guages. But if it comes to that, thats what I'll do. Quote Link to comment Share on other sites More sharing options...
Forrest Posted November 14, 2007 Share Posted November 14, 2007 Thumper, I don't know what year tach you're talking about, but I have noticed that the response rate in the 77/78 tach is much better than the 76 (and I assume earlier.) Using the Crane Cams Hi-6 rpm test mode you can watch it snap to the correct reading very quickly, whereas the 76 is slower and bouncy. I prefer the stock tach, too (it has my blinker lights built in) so I'm going to try and ditch the aftermarket tach if possible. Let me know how it goes Phil! Quote Link to comment Share on other sites More sharing options...
Thumper Posted November 14, 2007 Share Posted November 14, 2007 Thumper, I don't know what year tach you're talking about, but I have noticed that the response rate in the 77/78 tach is much better than the 76 (and I assume earlier.) Using the Crane Cams Hi-6 rpm test mode you can watch it snap to the correct reading very quickly, whereas the 76 is slower and bouncy. I prefer the stock tach, too (it has my blinker lights built in) so I'm going to try and ditch the aftermarket tach if possible. Let me know how it goes Phil! I am comparing my aftermarket autometer to my stock tach out of my 74' 260z. The autometer was much faster and more accurate. With the stock tach in first gear it was almost 400rpms behind and 100-300rpms inaccurate even in 4th gear. Quote Link to comment Share on other sites More sharing options...
Sideways Posted December 5, 2007 Share Posted December 5, 2007 Any luck/update with whats happened? Quote Link to comment Share on other sites More sharing options...
niner11 Posted December 29, 2007 Share Posted December 29, 2007 Phil, I ordered one of the MSD 8918's Did you ever have any luck with it? Quote Link to comment Share on other sites More sharing options...
big-phil Posted December 30, 2007 Author Share Posted December 30, 2007 no I didn't try it. Please let me know if it works. I was just thinking about that today on the way home to. Quote Link to comment Share on other sites More sharing options...
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