My K&N order arrived already and I have ordered the silicone intake reducers with clamps…<\/p>\n\n\n\n
But, the tach input thing… The diode thing didn’t work, but I think I have figured out why. Anything that connected the two coils to each other caused the engine to die pretty much immediately. I used multiple diodes, low and high value resistors, capacitors. Didn’t seem to matter. Anything that allowed any electrical signal to cross from one coil to the other failed.<\/p>\n\n\n\n
I would need a working ‘scope to verify this and I own one but haven’t seen it in years. Maybe it was lost in a move or maybe it’s buried in the storage building. Anyway, I think all these coupling experiments failed because the ignition unit may output a burst of high frequency pulses for each spark rather than a single DC pulse. It’s probably well beyond the frequency response of the tach input, so MegaSquirt still sees it as a single pulse. I suspect that this burst may also be over 12V, but if so, my meter can’t catch it.<\/p>\n\n\n\n
In short, this means that, in order to use MegaSquirt properly with the stock ignition, I will need to use optoisolators and OR their outputs together.<\/p>\n\n\n\n
What would probably be better is to go ahead and convert the ignition system, since I plan on doing that anyway. I was hoping on getting the fuel system fairly well tuned before adding another complex issue, but what the hey…<\/p>\n\n\n\n
The primary task to accomplish for the conversion is the construction of the trigger wheel. I should be able to do that with a little bit of jigging and my drill press.<\/p>\n\n\n\n
I will also need to purchase the appropriate coil pack. High performance units can be had from Summit Racing<\/a> for $60, stock replacements from\u00a0AutoZone<\/a> for $45 or salvage from $10-$30. I’m leaning towards the Accel unit, though salvage is probably fine and would include a connector. I will need the $15 wireset, too, but will probably need to cut them to length and\/or change the plug connectors.<\/p>\n","protected":false},"excerpt":{"rendered":" My K&N order arrived already and I have ordered the silicone intake reducers with clamps… But, the tach input thing… The diode thing didn’t work, but I think I have figured out why. Anything that connected the two coils to each other caused the engine to die pretty much immediately. I used multiple diodes, low … Continue reading Tach Input Issue<\/span>