JimJ 5,000+ posts
Tangled Up in Blue
I figure a gearhead like Jmac would be able to answer this question of mine...
I'm getting horrible ignition noise on radio frequencies from the AM broadcast band up to around the 6 meter amateur band (50MHz or so). It's definitely ignition noise of some sort, because it's RPM dependent. Furthermore, I get interference when I switch the key from off to accessory-standby...so I'm thinking that could be the fuel pump generating its own interference.
The noise is definitely radiated, not conducted - disconnecting the antennas makes it go away. I tried grounding the tailpipe to the frame, thinking it might be acting like an antenna for the noise; no help.
What I'm thinking of doing is taking Type 43 ferrite beads and placing them over the spark plug wires, once as they come out of the distributor and again before they go into the block. These are the same things (they come in different sizes, obviously) that you find on various electronic cords to keep radio interference out...I'm thinking the ferrite would stop the plug wires from radiating noise. The one problem I have with doing this is, would the ferrite cause any degredation in ignition performance?
I haven't done any reading on common mode chokes and the like in a while, so I'm not up to speed on how this all exactly works //content.invisioncic.com/y282845/emoticons/uhoh.gif.c07307dd22ee7e63e22fc8e9c614d1fd.gif
I'm getting horrible ignition noise on radio frequencies from the AM broadcast band up to around the 6 meter amateur band (50MHz or so). It's definitely ignition noise of some sort, because it's RPM dependent. Furthermore, I get interference when I switch the key from off to accessory-standby...so I'm thinking that could be the fuel pump generating its own interference.
The noise is definitely radiated, not conducted - disconnecting the antennas makes it go away. I tried grounding the tailpipe to the frame, thinking it might be acting like an antenna for the noise; no help.
What I'm thinking of doing is taking Type 43 ferrite beads and placing them over the spark plug wires, once as they come out of the distributor and again before they go into the block. These are the same things (they come in different sizes, obviously) that you find on various electronic cords to keep radio interference out...I'm thinking the ferrite would stop the plug wires from radiating noise. The one problem I have with doing this is, would the ferrite cause any degredation in ignition performance?
I haven't done any reading on common mode chokes and the like in a while, so I'm not up to speed on how this all exactly works //content.invisioncic.com/y282845/emoticons/uhoh.gif.c07307dd22ee7e63e22fc8e9c614d1fd.gif
