RFI from "new" '04 F150

[KO4OTL]

My cheap little VW Lupo had it's rubber spark plug cap scratched from a clumsy mechanic at some yearly maintenance check and created a small crack in the rubber (I fixed that with amalgamating rubber tape) and it then created a spark to the engine block. The ODB computer system then reported engine trouble and when reading the error code it said spark plug issue cylinder 3. I would imagine that a much more expensive F150 would have at least as good sensors for those kind of spark plug issues.

The engine can probably run with one cylinder dead, so perhaps remove that cable to the coil on one cylinder at a time and see what it does to the interference. Perhaps it's not related to the actual spark plugs and coils.

/Ubbe

No check engine light or anything. That's a good idea (assuming the ECU doesn't freak out) as far as deactivating one coil at a time. I'm pretty most of the ignition noise is coming from the driver's side of the V8.

 

[Ubbe]

I'm pretty most of the ignition noise is coming from the driver's side of the V8.

In my car, and I believe in most of them, have all electronic boxes at the drivers side and also under the hood everything related to electronic valves for ABS and so on are located at the drivers side. Sometimes there's RF interfering pules from the sensor system that sits on each wheel for the ABS/antiskid feature but gets activated when the ignition key are turned on and not only when the engine run.

/Ubbe

 

[speedway_navigator]

The OPs engine uses coil-on-plug.

That technology came from Indycar racing from what I know.

 

[otobmark]

I can tell you that a citizen band radio in that vintage of ford 4.6 will not work with the engine running. I have never had a problem VHF and up that was noticeable- as in hearing artifacts- but could not say whether or not there was any de-sense. Like OP my am broadcast radio is usable if not ideal.

 

[KF0NYL]

I have a 2010 F 150 with the 4.6L. It only has 69,500 miles on it and the previous owner did a very good job on keeping up with the maintenance.

I have not had any issues with my VHF/UHF radio or my GMRS radio. I have not tried CB/HF yet so don't know if I will have any interference there.

I always run the positive radio lead to the battery and the radio ground directly to a good chassis ground for all two way radio installs.

You can also ground the radio body to a chassis ground. If the radio does not have a dedicated group lug then you can use one of the mounting bracket screws.

I had some intermittent noise on VHF/UHF in my 2023 Ford Escape. I ended up placing clamp on ferrite beads on the power wires going to the radio along with a clamp on ferrite bead on each end of the main cable going between the alternator and battery. That took care of the intermittent RFI issues.

 

[KO4OTL]

So I've replaced all the spark plugs (no issues with doing that!), and replaced one of the RFI suppression capacitors (that was a suggestion from an F150 forum). I did unplug one coil pack at a time, but no real difference in the VHF noise level (it's either none or all of them). I've also hard mounted (nmo mount) my 1/4 VHF antenna to the roof. I think the noise has reduced somewhat, and I still have big ignition-type noise issues on the CB while running. What kills me is my '92 F150 with the 5.0 V8 has awful noise on AM BCB, a hint of noise on CB (with load noise from the windshield wiper motor) and zilch on VHF/UHF.

Back to the '04, I'm gonna replace the other RFI suppression cap, and maybe do some more bonding and see what happens. Thought about putting a bunch of aluminum foil on the underside of the hood and see if that helps haha (half serious there). Only other thing I can think of is alternator related, or something else ignition related?

If I didn't go into weak signal areas semi-frequently, I would just live with it, but it becomes greatly noticeable as signal strengths from repeaters and such degrade.

 

[mmckenna]

I've also hard mounted (nmo mount) my 1/4 VHF antenna to the roof. I think the noise has reduced somewhat, and I still have big ignition-type noise issues on the CB while running.

OK, so "hard mounted", does that mean a permanent mount, or did you do something else?

Where is your CB antenna mounted?

Did you run your power as suggested? Positive radio power off the positive terminal on the battery, and ground off a body ground very near the radio?

Did you ground the radio chassis, separate from the negative power lead?

 

[Ubbe]

One thing that where very useful in my work as a radio tech was the speaker element from a vintage telephone handset with a 1uF poly cap in series. Using that I could listen for any strange noise on telephone lines, network data lines and also directly over a car battery to hear how much generator noise there where. It could be a too high resistance in the battery or a bad generator that made noise go into a radio and create problems. It was a super helpful tool in all kinds of work.

I never saw any of our installation guys do anything else than connect the negative and positive power lead, with a fuse, directly to the battery pole and never heard of any issues doing that. But customers would sometimes come to us with a generator noise issue that have had their installation being done elsewhere or by themselves.

/Ubbe

 

[mmckenna]

I never saw any of our installation guys do anything else than connect the negative and positive power lead, with a fuse, directly to the battery pole and never heard of any issues doing that. But customers would sometimes come to us with a generator noise issue that have had their installation being done elsewhere or by themselves.

Installation guides for most of the higher tier LMR radios will instruct the installer to connect the positive at the battery positive and negative to body ground. In fact, some radios I've installed specifically come with power lead kits with short negative wires since that's all that's required to tie down to a body ground.

Way back in my early years, I installed an amateur radio in my own vehicle and followed Yaesu's advice and tied both positive and negative down direct to the battery. I had bad alternator whine on that radio. To fix it, I took the negative lead off the battery terminal and tied it to chassis ground.

I believe the amateur radio/CB radio/hobby radio manuals suggest tying both down directly to the battery is done to remove the chances of an inexperienced user screwing up older positive ground vehicles, or accounting for poor vehicle wiring maintenance.

 

[KF0NYL]

Another reason for running the negative wire to chassis ground is that pretty much all newer vehicles from 2016 and up all have battery management systems. The BMS gets it information from the module attached to the battery negative terminal.

Every vehicle I have owned the has the auto start stop system and the BMS have all stated in the manual to ground accessories to chase ground and also to always connect the negative lead from jumper cables and battery chargers to chassis ground for the same reason.

 

[mmckenna]

Another reason for running the negative wire to chassis ground is that pretty much all newer vehicles from 2016 and up all have battery management systems. The BMS gets it information from the module attached to the battery negative terminal.

Yep, another good reason. Doesn't apply to his 2004, but it's just generally good practice.

 

[KF0NYL]

I found out today that a 2015-2015 Chevy 1500 and a 2003-2003 Dodge 1500 are noisy. The Doge was worse. I was working POTA using a REZ Recon antenna and I heard the noise on my radio as soon as the Dodge pulled into the parking lot and it only got worse as he got closer to me. The Chevy was only noisy when he was close to me.
I was setup running portable outside of my vehicle.

Yep, another good reason. Doesn't apply to his 2004, but it's just generally good practice.

AS/S and BMS definitely won't affect a 2004 vehicle. I don't know when manufactures started having the AS/S and BMS. I know my first one was a 2016 Jeep Cherokee Sport.