When I key my CB the engine will misfire severely. This happens intermittently. I have checked for chaffed wires and antenna cable.
Has anyone else had this problem? Was the problem discovered?
2007 FLHTCU

 

Going to have to watch this thread. Got the same bike. Mine works fine now but what if....

 

stock cb?

some guys add amplifiers and i have seen RF from amplified systems cause all kindsa trouble.

next step...plugs and wires.

the plugs and wires for the late model twin cam are crucial- the ecm relies on ion sense to determine the burn condition in the combustion chamber.
even screamin eagle can be a problem, stock stuff will work better.

worn or out of spec wires or non-resistor plugs may be an antenna and picking up rf.

try reseating the ecm connector too.

Mike

 

Well I can honestly say I have never heard of this problem before.. Good luck! Hopefully someone else has run into this before.

 

It's possible your battery is marginal and the extra draw of the small amp in the CB is too much. I don't think this is particularly likely, just worth mentioning in case you get down to scratching your head. More likely is as has been mentioned earlier, you have RF getting into an electronic component related to the ignition.

With it being intermittent, I'd check the antenna cable and connectors, and the antenna itself, real closely. Have the whole enchilada evaluated by someone who's familiar with RF and related issues. If there's an intermittent connection, it's possible the cable itself is radiating a lot of power sometimes (versus the power being radiated by the antenna), which would probably be in close proximity to the electronics under the seat and/or in the side panels.

Alan

 

..just for giggles, make sure you have the cb antenna and am/fm antennas screwed onto the right posts...

wondering if incorrect antenna loading could be sending RF to ground

mike

 

If you have a 50 ohm, 5 watt or greater dummy load that you can transmit into, this will aid greatly to determine if you are radiating interference into the ECM or not. By transmitting into the dummy load, which will absorb the RF energy, and your bike still misfires would indicate it's a DC current/voltage/battery, or dc wiring issue. Is this a factory setup or something put in aftermarket? If it's an aftermarket install make sure that the positive lead is not sharing the same cable bus that powers the ECM or any control lines to/from the ECM. The current pull when transmitting can starve the ECM if you are sharing the same power cable. The cb's black or negative power lead should go directly to the battery's negative post. Do not rely on grounding to the frame only, as this could set up 'current loops' which could induce all kinds of havoc into your electronics.

 

Try wrapping your ECM with aluminum foil, it keeps out the RF's and works for my head too!

Seriously, I did have a time when I worked at a RF live area, the bike would die & not start till I walked it a bit.

.

 

Check for codes that may point you in the direction of your problem.

I recently stopped at a dealer in Owen Sound, Ontario to check out their T-shirts. I parked my bike in the designated parking area close to the Service Department Entrance and went in and had a look around. When I climbed back on my bike the alarm went off and the starter was dead. First thing to come to mind was the FOB battery must be dead. I'm about to get off the bike so as to go back into the dealership and buy a battery, when a Tech. pops up and says it's not my FOB. He points to a Tower a couple hundred feet away. Tells me to move my bike away from the Tower. I push the bike no more than 25 feet and it starts right up. Tech told me this happens all the time to bikes parked in their parking lot.

Makes you wonder what those RF's are doing to your brain.

 

Eureka! I figured it out!
It wouldn't restart after fueling one day so I trailered it to my Dealership reluctantly. I hadn't had any luck after taking everything apart and checking and checking.. I asked the dealership to simply put their scan tool on the bike and give me the results.
They got intrigued by the CB kill the motor issue and kept it one week. They worked and admitted they did not know what caused that issue.
I got it home and was getting ready to ride to Kansas so I wanted to put new throttle cable on it. I found that I had trapped the two wires for a single LED light, between the air cleaner back plate and the intake assembly. No dead short or blown fuse. Just a capacitative situation.. Apparently it was similarly tuned to my CB radio transmission frequency and when I keyed the mic. the transmission power would infiltrate my electrical system. I cleared the wiring issue and LED's are bright and absolutely no problems. This bike runs great and no problems. It only took two years of continually worrying about it to find it on a chance.
Thought you might want to know.