Rpm Signal Noise

For discussing how to choose sensors and create a wiring harness for all Bowling and Grippo versions of the MegaSquirt® EFI controller.
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Scotty Dont
MegaSquirt Newbie
Posts: 5
Joined: Wed Oct 01, 2008 7:49 am

Rpm Signal Noise

Post by Scotty Dont »

There seems to be some noise in my ignition signal. I have tried to search and I can't find the answer, I am running a shielded wire on my fuel only ms2 v3.0 and I want to know if both sides of the shielding need to be grounded. And What is the proper way to route and set up the shielded rpm signal wire.
Matt Cramer
Super Squirter
Posts: 2951
Joined: Sat Jul 03, 2004 11:35 am

Re: Rpm Signal Noise

Post by Matt Cramer »

Normally you'd only ground one side of the shield to avoid ground loops. Exactly what sort of ignition system are you running?
Scotty Dont
MegaSquirt Newbie
Posts: 5
Joined: Wed Oct 01, 2008 7:49 am

Re: Rpm Signal Noise

Post by Scotty Dont »

Its a vr sensor in the dist and im getting signal from the neg side of the coil. This is a Starion G54b in a mitsubishi mighty max with a sheet metal mpi intake and a holset hx35.


Should I route the rpm signal wire with the main harness or should I keep it separate and away from other wires?
Matt Cramer
Super Squirter
Posts: 2951
Joined: Sat Jul 03, 2004 11:35 am

Re: Rpm Signal Noise

Post by Matt Cramer »

The negative side of the coil is a noisy place to trigger from. How are D1, D2, and the input capacitors set up?
Scotty Dont
MegaSquirt Newbie
Posts: 5
Joined: Wed Oct 01, 2008 7:49 am

Re: Rpm Signal Noise

Post by Scotty Dont »

Where should I trigger from then? And the ecu was purchased from you (diy) it came loaded with 2.888 all I did was change the board to what I said in the megamanual "For triggering off the coil negative terminal/points"

D1 has the wing diode
D2 has the 22v zener diode in reverse

and I am unsure about the input capacitors but like I said the ecu was built by diy
Matt Cramer
Super Squirter
Posts: 2951
Joined: Sat Jul 03, 2004 11:35 am

Re: Rpm Signal Noise

Post by Matt Cramer »

You could trigger it off the VR sensor instead, might get a cleaner signal. Or try cutting the XG1-XG2 jumper and running a wire from XG1 to an external ground.
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