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

Hi,
Can My MS Controller Cause An Ignition Misfire? I'm Using MS2 V3 With 2.90500. Fuel Only. Tach Signal Off Coil Negative. Engine Won't Stay Running. Tracked The Problem Down To An Ignition Misfire Until It Dies. I Have Replaced Plugs, Wires, Cap, Rotor, Distributor Twice With New Ones And four Different Coils. Constant 12V+ To Coil. I Finally Ran A Jumper Wire Over To Another Car With An HEI Distributor And The Problem Went Away ( Did Not Seem Too Bother The Hei Ignition In The Second Car). The Problem Seems To Be The MS Controller Shorting Out The Coil. So I Bought A Second MS2 V3 With 2.92000, Same Problem. What Am I Doing Wrong? Tune? Configration? Jumpers On The Board For Tach Input?
A Datalog Does Not Show Anything Unusual, Just The RPM Tapering Down To 0.
Any Comments Or Suggestion Will Be Greatly Appeciated.
Thanks,
Dale

Try a 20 to 24 volt zener diode in line with the coil negative wire, banded end to the coil. Usually I've recommended this for protecting the MegaSquirt from ignition noise, but it will also prevent the MegaSquirt from grounding the coil.

Loopershop wrote:Hi,
Can My MS Controller Cause An Ignition Misfire? I'm Using MS2 V3 With 2.90500. Fuel Only. Tach Signal Off Coil Negative. Engine Won't Stay Running. Tracked The Problem Down To An Ignition Misfire Until It Dies. I Have Replaced Plugs, Wires, Cap, Rotor, Distributor Twice With New Ones And four Different Coils. Constant 12V+ To Coil. I Finally Ran A Jumper Wire Over To Another Car With An HEI Distributor And The Problem Went Away ( Did Not Seem Too Bother The Hei Ignition In The Second Car). The Problem Seems To Be The MS Controller Shorting Out The Coil. So I Bought A Second MS2 V3 With 2.92000, Same Problem. What Am I Doing Wrong? Tune? Configration? Jumpers On The Board For Tach Input?
A Datalog Does Not Show Anything Unusual, Just The RPM Tapering Down To 0.
Any Comments Or Suggestion Will Be Greatly Appeciated.
Thanks,
Dale

The tach input circuit can be configured in a number of ways - which involves reading a multitude of notes. This is the one I use.

Hi,
I Installed A 24V Zener Into The Harness Early On Because I Was Having Tach Spikes During Cranking. I Tried Adding Another 22V Zener In Addition To The 24V, Did Not Seem To Help. I Also Tried Adding Increasingly Higher OHM Resistors Unlit MS No Longer Got A Tach Signal, Did Not Seem To Help.

trakkies - Both MS Controlers Are Assembled Like Your Diagram Except D2 Is The Supplied 22v Zener

I Don't Understand How MS Can Cause The Problem. I Installed An Inline Spark Tester (Looks Like A Flash Bulb), Spark Is Not Real Bright And Not Consistent Until The Engine Dies. When I Disconnect MS From The Coil And Jumper To Another Car, Both Car Idling, The Spark Is Very Bright And Smooth And Does Not Die. The Interesting Thing Is The Other Car Has An HEI, And MS Does Not Bother The HEI.

I've Tried A Pertronics Convertion And Points
Thanks,
Dale

If you spin the distributor with a drill instead of having it run on the engine, what does the spark do?

Do you have a data log of the problem? It may not be the MS interfering with the ECU.