September 14, 20222 yr comment_645363 2 hours ago, Emerald280Z said: Wanted to revive this to see if you all can help me with my tach. Did 280ZX upgrade to my 280Z. Now it reads well at idle then if I blip to throttle it goes to 0. Eventually it goes up but bounces around. I’ve tried a new tach and it does the same. Using a FAST PS40 1.4ohm resistance coil with matchbox distributor. You might have luck with this: https://www.technoversions.com/TachMatch.html Link to comment https://www.classiczcars.com/forums/topic/67492-280z-tachometer-problems-with-a-zx-e12-80-ignition-module/?&page=4#findComment-645363 Share on other sites More sharing options...
September 14, 20222 yr comment_645364 Just now, Racer X said: You might have luck with this: https://www.technoversions.com/TachMatch.html First he needs to take out the TIU and 10K resistor to see if he has a problem. I would not be surprised if getting rid of those (along with ensuring the stock resistor is in place) fixes his problem. Link to comment https://www.classiczcars.com/forums/topic/67492-280z-tachometer-problems-with-a-zx-e12-80-ignition-module/?&page=4#findComment-645364 Share on other sites More sharing options...
September 14, 20222 yr comment_645365 Also, here is a picture of the resistor in the passenger footwell of my 260Z. As @Zed Head said, it's taped up like a mummy. It might have different connectors in the 280Z, but this should give you an idea of what you should be looking for. It will probably be below where the engine wiring harness comes through the firewall. Link to comment https://www.classiczcars.com/forums/topic/67492-280z-tachometer-problems-with-a-zx-e12-80-ignition-module/?&page=4#findComment-645365 Share on other sites More sharing options...
September 14, 20222 yr comment_645368 That's the original round style that they used on the 260Z's. The 280Z's used the rectangular one like in the drawing you posted. It looks just like the drawing. It's folded over then taped up, so it's a different shape of lump. Link to comment https://www.classiczcars.com/forums/topic/67492-280z-tachometer-problems-with-a-zx-e12-80-ignition-module/?&page=4#findComment-645368 Share on other sites More sharing options...
September 14, 20222 yr comment_645369 I didn’t immediately see the stock resistor there as I quickly removed the TIU with my 3yr old in tow. Just removing the TIU made the tach work! Is there a benefit or harm to removing the resistor I soldered in if the tech is working? Thanks again and happy I found this thread as FB responses months ago were not this helpful. Link to comment https://www.classiczcars.com/forums/topic/67492-280z-tachometer-problems-with-a-zx-e12-80-ignition-module/?&page=4#findComment-645369 Share on other sites More sharing options...
September 14, 20222 yr comment_645373 1 hour ago, Emerald280Z said: I didn’t immediately see the stock resistor there as I quickly removed the TIU with my 3yr old in tow. Just removing the TIU made the tach work! Is there a benefit or harm to removing the resistor I soldered in if the tech is working? Thanks again and happy I found this thread as FB responses months ago were not this helpful. FB is good for posting pictures and getting lots of bad advice that buries the responses from the few knowledgeable people. Link to comment https://www.classiczcars.com/forums/topic/67492-280z-tachometer-problems-with-a-zx-e12-80-ignition-module/?&page=4#findComment-645373 Share on other sites More sharing options...
September 14, 20222 yr comment_645375 that is the truth. happy i found this and thankful for the replies. removed the resistor I put on by coil and all seems to be good. running a smooth 850-900 idle Link to comment https://www.classiczcars.com/forums/topic/67492-280z-tachometer-problems-with-a-zx-e12-80-ignition-module/?&page=4#findComment-645375 Share on other sites More sharing options...
September 15, 20222 yr comment_645376 1 hour ago, Emerald280Z said: that is the truth. happy i found this and thankful for the replies. removed the resistor I put on by coil and all seems to be good. running a smooth 850-900 idle No fuss, no muss, no unsightly build-up. We are glad your Z is operating normally. I would not be surprised if it drove better now. Link to comment https://www.classiczcars.com/forums/topic/67492-280z-tachometer-problems-with-a-zx-e12-80-ignition-module/?&page=4#findComment-645376 Share on other sites More sharing options...
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