kutukutu1

iTrader: (5)

Hello,

Ive been fighting with this for over a month trying to figure out what is going on.
Its a 12A bridgeport and i am running fuel only.
When i crank, the rpm signal only goes up to 12 rpms and i know thats not right.
I have a relay board and i have measured the voltage all the way into the MS and i have proper 12V into pin 24.
I am running of the negative coil signal and i have C30 and C12 installed with the D2 zener reversed. I have xg1 to xg2, Tachselect to optoin and tsel to opto out.
Coils are brand new and they have a very strong spark.
I am lost on what else to look for. I am not sure on how to trouble shoot the tach circuit to see if a component might be bad.
Is there something in tunerstudio that needs to be selected to tell it its negative coil signal? I have it in fuel only

Aaron Cake

iTrader: (1)

I think this is covered in your other thread, but in case someone else is looking at this.

To set up a MS V3 (or 3.5) board for triggering from the negative side of the coil (dizzy) do the following:

Jump TachSelect to OptoIn
Jump XG1 to XG2
Jump Tsel to OptoOut

D1, D2, C30, C12 should be installed.

I have never seen the need for any reverse biased Zener when triggering from a 1st gen coil. Always just used the stock Opto circuit on the V3 or 3.5 board (or for that matter, back in the day, the 2.2 board).

If ignition spikes are experienced then try adding a series resistor to the ignition input. Start at 10K. Move down if you start to lose RPM signal.

TunerStudio needs to be set to accept a basic trigger so in Wheel Decoder options, select "Basic Trigger" then disable all the ignition output settings.

Post your MSQ file so we can check the trigger settings.

kutukutu1

iTrader: (5)

Thanks aaron, I posted this before I figure it out. I appreciate the help.