All Z's Posted December 10, 2007 Share Posted December 10, 2007 I have a customer's car at my shop that I can not set the trigger offset angle on properly. My problem is that when I adjust the trigger angle it does not change the engine's ignition timing. This can be verified using a timing light with the engine running. I have tried offsets from -10 to 180 and everything inbetween with absolutely no effect on timing at all. The only way for me to get the car to run properly is to set the entire timing map in MS to 55 degrees of timing or more. 55 degrees in the timing map will get me to about 15 degrees of actual timing verified using a timing light with the engine running. With the timing set like this the car runs great until 3k rpm and then the tach input goes crazy. Anything over 3k will make the tach (in Megatune) jump wildly between 3 and 14k rpm. I believe this problem to also be related to my offset angle too. Here is my theory why. Anything below 3k gives me a perfect steady tach input signal. Also, if I take timing out of megasquirt (from 55 deg to about 40) the car will run poorly due to low ignition timing but it will then rev past 3k rpm without losing it's tach signal. This is very frustrating to me and my customer. It is my third install in a Z and I have worked with several other systems in early Z's and have never encountered a problem like this one. Here is a little info on the car: '77 280Z, N/A 280ZX engine with only minor mods, '77 VR distributor (green wire grounded and red connected to pin #24 via shielded wire) Info on the MS setup: DIY Autotune v3.57 board with MSII processor, MS relay board, VB921 firing coil directly (spark output is inverted), v2.6 software (have tried MS extra as well), board is jumped for VR input and I am triggering off the rising edge of the tach signal. I have followed all instructions for setting up the VR distributor on megamanual and on this site as well. If I have left out any helpful info let me know and I will post it up. Any advice on where to start on this problem would be greatly appreciated. If you are local (DFW area of TX) I would be glad to buy anyone who helps a few beers to show my appreciation.... Thanks, Kyle (w/ All Z Car Specialist) Quote Link to comment Share on other sites More sharing options...
Matt Cramer Posted December 10, 2007 Share Posted December 10, 2007 Could you post your MSQ so I can check the ignition settings? Quote Link to comment Share on other sites More sharing options...
All Z's Posted December 19, 2007 Author Share Posted December 19, 2007 Sorry to not get back to you sooner Matt, been very busy w/ school. I will try to post an msq for you asap. I now have the trigger offset set so that my timing is accurate w/ a timing light vs. MS readout. My offset ended up being -59. Seems strange to me but it works so far as I can tell... The only problem is that I am still losing a clean tach signal at anything over 3k rpm. On occasion it will rev past there nearly to redline but 9 times out of 10 it doesn't. When the car will not rev the tach is not dropping out to 0 rpm but is bouncing between 3k and 10k+ rpm. Any thoughts? Thanks, Kyle Quote Link to comment Share on other sites More sharing options...
naviathan Posted December 19, 2007 Share Posted December 19, 2007 Green wire grounded where? Green wire should be connected to your shielding on the pin 24 wire. Quote Link to comment Share on other sites More sharing options...
All Z's Posted December 19, 2007 Author Share Posted December 19, 2007 The green wire is in fact connected to the shielding for the tach signal wire. Red wire connected directly to pin #24. And the shielding is in turn grounded inside the car very near the point where the tach signal wire is connected to the relay board. It shares a ground point with the main ground for MS. Grounds have been checked and rechecked for continuity and show 0.1 or less ohms of resistance. Thanks for the suggestion though, Kyle Quote Link to comment Share on other sites More sharing options...
naviathan Posted December 19, 2007 Share Posted December 19, 2007 You said this was a 77 dist? Just checking, but was there one or two VR pickups in there? I know some of the Z dists had 2. Have you checked your pots, I believe it's R56 and R52? Don't quote me on those numbers as I haven't messed with my MS in a while. Although if Matt will humor me and send a kit to an APO address I could tinker with one in Iraq...lol Anyhow, check the two VR pots and make sure they are turned completely counter clockwise until the click. It seems the VR pickups are very weak and MS has a hard time if the pots aren't completely open. Quote Link to comment Share on other sites More sharing options...
All Z's Posted December 20, 2007 Author Share Posted December 20, 2007 The pots are completely open already. I changed the distributor pickup and now the tach signal seems to be pretty clean. It still acts up a little but is not nearly as bad. Thanks again for the input and I will keep eneryone posted on my progress. Kyle Quote Link to comment Share on other sites More sharing options...
Chemicalblue Posted December 20, 2007 Share Posted December 20, 2007 Hey Kyle. Good that All Zs is in the Hybrid z battlefront now. Nice to see you on forum. Finally:burnout: Tommy Quote Link to comment Share on other sites More sharing options...
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