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Toyota COP no tach

 
Old 03-28-2017, 11:38 AM
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Default Toyota COP no tach

1.6 1991 miata.
Hi guys, I have recently installed a set of Toyota COP, I run megasquirt 2 soldered by myself. I've already read all the threads with tach issues, I have done everything. The 4,5 wires on the ignitor are connected together and to tach signal from all the coils. Resistance between those wires and ground indicates 1,5k Ohm. I've checked all the coils for continuity between tach and gnd pins, none are connected. Indicating coils are working.
The diagnostics port is connected properly, has 12v, gnd, and tach working. I've placed the 1k resistor between ign and 12v. Furthermore voltage between ign and gnd is 13 when car powered off, once started indicates roughly 1.4. With the increase in the rpm the voltage lowers indicating more often grounding. Which in theory should be exactly how it should work, yet it doesn't. Help me out guys.

P. S. The tach worked prior to cop install with stock coils.
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Old 03-28-2017, 11:39 AM
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unplug coils one at a time and see which one is causing the ground fault...
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Old 04-04-2017, 03:03 PM
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I did try but that's not the problem I think, they are all working fine, does anyone know which kind of signal stock 91 coils produce for tacho? I suspect the signal is the exact opposite of what I'm currently getting out of my cop, a 12v signal on every ignition, as opposed to current 12v with grounding every ignition.
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Old 04-04-2017, 03:09 PM
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so with the car running, you put your DMM in diode mode, and connected the leads to IG- and GND and didn't hear a solid beep but a rapidly pulsing one?
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