MSefi.com read only forum (Jan.15,2018)

Thanks for your comments James. I chose to use the transistor switch mod, because in testing I also felt that the output of the HEI 8 module was marginal. The additional gain with the transistor totally fixed the issues I was having. Keep up the GREAT work, as I follow your work closely ...

Lance,
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The addition of the switching transistor in the opto input did the trick! That and discovering that the polarity of the input as documented is wrong. The documentation for the HEI says that the orange lead for the Chrysler VR is positive, however, when used with a HEI 8 module ...

Thanks for the reply Lance. It's nice to know that I'm not the only one seeing this problem. I have a nice dual trace scope, and can easily verify that the trigger, return, and control lines are correct. I do believe that the gain of the 8 pin HEI module varies whether or not it is in the ...

HEI 8 problems

Here's the setup:

1968 Dodge Super Bee, 426 Hemi, Cross Ram intake w/ 2 Holley 670 cfm throttle bodies, MegaSquirt 2/3 firmware v 2.35 with Relay Module, GM HEI 8 pin ignition module, input to HEI module from locked stock Chrysler magnetic pickup distributor. The wiring to MS is per ...