VR sensor, synch loss reason 2, worked for months, MS3 Pro

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billthejim
MS/Extra Newbie
Posts: 3
Joined: Sat Dec 06, 2014 6:06 pm

VR sensor, synch loss reason 2, worked for months, MS3 Pro

Post by billthejim »

So a couple days ago my engine stopped holding sync when not just cranking the starter motor.

just cranking the starter motor works just fine, resulting in a tooth log like the first one linked.

however when i try to inject any fuel, the whole thing goes haywire, bouncing between 0 and some rpm, and giving a synch loss reason 2.

tooth logger linked below.

the engine worked fine in this configuration until this issue started, any ideas on what could have broken or changed?


the VR sensor is connected to the ckp inputs with a 10kohm resistor in line with the positive input.

is the "noise filtering" menu something to look into more? is it for this kind of purpose?


things I've tried so far:
Swapping VR sensors
checking and grounds (none of these changed, pretty much everything except sensor returns ground to cylinder head)
switching to a 10 kohm resistor between ckp + and - wires, in parallel with the sensor, instead of inline with the positive input
adding shielding around the wires
moving spark cable farther away from the sensor wires
inspecting the board itself for any obvious blown circuitry
virtually every combination of "ignition input capture" and "second trigger active on"


apparently the ms3 pro doesn't have any variable potentiometers to adjust like some other versions, so no luck there.

is there a way to check if the solution would be something along the lines of this guy's op-amp issue?
http://www.msextra.com/forums/viewtopic ... 01&t=50408
Matt Cramer
Super MS/Extra'er
Posts: 17499
Joined: Thu Apr 16, 2009 8:08 pm

Re: VR sensor, synch loss reason 2, worked for months, MS3 P

Post by Matt Cramer »

The first tooth log looks great, second one is missing a lot of signals. It's filtering out too much - try turning noise filtering off.
Matt Cramer -1966 Dodge Dart slant six running on MS3X
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