Vehicle RFI Regulations

[nickwilson159]

Are there any such laws in the United States that dictate acceptable RFI levels in a newer vehicle (2018 model year in this case)? Some Google searching isn’t turning up any answers, but perhaps I’m not using the right terminology in my search.

The fuel injectors in my Honda CRV are spewing out RFI, to the tune of -30 to -40 dbm at ~2000 RPMs across the VHF band per a TinySA positioned in the back of the engine bay about 12” away from them. The dealership has inspected it and said everything is working as intended, and I’ve tried every possible remedy you can think of short of replacing the injectors themselves or sleeving the leads with shielding (since that requires removing the manifold & fuel rail to even access them). See thread here for some specifics:

Fuel Injector RFI (Radio Interference)

I have a few two-way radios installed in my 2018 CR-V EX, and have been chasing interference on it for some time (specifically on the VHF band). I've done pretty much every recommended fix from the two way/ham radio crowd (all plugs & ignition coils replaced with new NGK parts, bonding straps...

www.crvownersclub.com

Other, newer Honda CRVs with the same engine do not have these issues. The 2017 & 2018 were plagued with issues with the fuel injectors, and most needed replacing; revised versions were present in 2019 & later models.

Obviously Honda says they’re fine and doesn’t want to cover it, so I’m trying to see if there is another avenue here, or if I’m S.O.L.

 

[mmckenna]

I don't know about 'laws' for that, specifically, but it would be covered under the FCC Part 15 "unintentional radiator" rules. There are some specific requirements about suppressing RFI below a certain level.

However, the rules also say that if something is causing interference to another device, you move them apart, so the FCC expects some amount of 'do it yourself' here.

 

[RFI-EMI-GUY]

Solutions:
Snap on chokes on the injector leads. Near to injector.
Ground straps and brass contacts at 4 corners of the hood.
Chokes on any wires leading through firewall that may re radiate. Start with aftermarket wiring like your radio power leads. Grounded copper or aluminum foil tape on anything you cannot choke, like massive harness.
Permanently mounted antenna, like NMO on roof.

 

[bharvey2]

Not sure I've ever ran across specific laws against RFI interference at as it applies to vehicles. If there were, I'd think that the electric vehicle /AM radio noise problem wouldn't be as great as it is. That being said, I think your troubleshooting attempts and repairs are you best bet. RFI-EMI-GUY has some good suggestions and that would be good placed to start. More dramatic and time consuming might be to change 1 plug/injector at a time and see if there are changes. (If you go that route, don't cheap out. Look for OEM products.) It's possible that you have a bad device that is creating hash on its respective wiring harness. One thing to consider is a noisy fuel pump. They have been known to wreak RF havoc. If it is a bad fuel pump, quite often you could determine that at a cold start before the engine turns over. The fuel pump will spin up in the ignition on position before moving the ignition switch to engage the starter.

 

[slowmover]

Ignition Notes on RFI

 

[MTS2000des]

I had a 2005 Hyundai Elantra that doubled as a broadband noise generator, from both the ECU and TCU. So bad that the factory AM/FM radio had hash and trash on both AM and FM. It generated -85dbm from AM to 1 GHz across the band. Hyundai did have a service bulletin that involved the dealer/techs wrapping the connectors and cables in metallic shielding tape, adding ground straps, and repositioning the AM/FM antenna lead away from the wiring harness.

Ironically, the 2013 Elantra Limited I have owned for a decade is full of tech and is as quiet RF wise as a mouse. My APX8500 and XPR550E don't experience anything at all.

 

[slowmover]

Out on the big road (10k miles/monthly) I don’t encounter too many noisy vehicles, but they exist.

Some are horrendous. I usually figure it’s non-factory devices in the vehicle. Refrigerator compressors and the like.

The others (like yours, I suspect) generally buzz their way past me where engine rpm is evident.


Now, whether the product linked below works or not, be sure to prank your friends you got an aerosol spray can of anti-RF paint and it did the trick

Noise is always present in mobile is my take (HF radio user). How hard I’m willing to work at sussing it out is the actual question.

.

 

[merlin]

No such animal as far as FCC is concerned, at least it isn't a 1958 Marconi spark gap transmitter on wheels.

 

[slowmover]

KØBG.COM

A Web Site For Mobile Amateur Radio Operators

www.k0bg.com

Be comprehensive in approach.

Don’t give up.

.

 

[madrabbitt]

Solutions:
Snap on chokes on the injector leads. Near to injector.
Ground straps and brass contacts at 4 corners of the hood.
Chokes on any wires leading through firewall that may re radiate. Start with aftermarket wiring like your radio power leads. Grounded copper or aluminum foil tape on anything you cannot choke, like massive harness.
Permanently mounted antenna, like NMO on roof.

One thing to consider is a noisy fuel pump. They have been known to wreak RF havoc. If it is a bad fuel pump, quite often you could determine that at a cold start before the engine turns over. The fuel pump will spin up in the ignition on position before moving the ignition switch to engage the starter.

This, that. (Some of which you've already done) (also look for any loose or broken OEM ground straps)

And my additions:
1. If i stick a spectrum analyzer under the hood of my truck, even though ive got lots of electrical and RF bonding, plus RFI reduction chokes on power harnesses, i'd probably see a bunch of RF all over the spectrum too... vehicles are noisy. (although, i'm well aware of the honda injector issues for another reason) So, why exactly are you analyzing where the RF actually is? You probably should be focusing your attention to where the RF shouldnt be, which per your post, seems to be your antenna(s)

2. Reading thru your external linked post, plus this post, there are no details on your radio setup.

The quick things we probably need to know:
-How are the radios powered. Be specific. Where is the power and ground connected, what is inline.
-How and where are the antenna(s) mounted.

 

[speedway_navigator]

Back in my early racing days EMI was a major problem with the car to pit radios. I suggested some of the fixes you guys mentioned but the engine guys said no way, you're not messing with my horsepower. Then the Edge performance monitor and Pi came along with digital displays in the cockpit and they had problems with EMI, so the engine guys had to make some changes. The Pi display rotated through screens at a 3 Hz rate.

I didn't realize how much the EMI affected the signal until I was at the track one day when little Al's team was testing.
I left the track and was driving up Georgetown road parallel to the front stretch listening to him talk to crew chief Dennis Swan, it started breaking up as I passed gate 9A outside turn 4.

I was at the light at 30th street and then Al came in with full quieting saying "I'm out of fuel, I'm coasting in from 4".
That's when I found out how bad EMI was.

Alfa Romeo cured this when they went with coils on each plug so the electrical system only switched 12VDC.