Fighting Noise In A 2018 Honda CR-V

[nickwilson159]

Long time lurker, first time poster. I've usually been able to find the answer to my question by searching through forum threads, but I'm stumped this time. This is a copy of a post on RadioReference, but I'm posting it here since the advice I've read on these forums seems far more reliable.

The noise in question:

https://www.youtube.com/watch?v=THYdX08vCmU

I had the radio professionally installed by NYCOMCO, including an NMO mounted Comtelco 1/4 wave (drilled a hole in the roof) and Comtelco Micro Loss 900 coax. Removing the antenna eliminated the noise, but just to be safe, I ran a second ground to the seat bolt - no changes. I then installed 4 ground straps along the exhaust, tailgate-to-body, hood-to-body, engine block-to-body, and radio body to seat bolt just to be safe - again, no changes.

The next course of action were ferrite beads, which were applied to the coax and various wires around the engine bay. The beads on the leads to the coil packs were the ONLY thing that made a dent in the noise of everything I've tried. Unfortunately, as the leads to the coil packs were so short, they aren't exactly mounted as they should be - and most of the wiring is still encased in plastic.



Any ideas on where to proceed from here? Some Googling made mention to using 3M copper tape to wrap around the offending parts, but I'm not sure if that'd actually work or not.

Thanks in advance...

[MotoFAN]

Do you have inline DC power filter installed? If no, it might help. If no, you have to find a problem with faulty spark or spark plug wires.

[abbylind]

Thats definitely ignition noise. Spark plugs (must be resistor) ignition wires, yours has the coil over Replace them. Look for loose or corroded connections. Dont disregard the connections for the tach. It takes impulses from the ignition. I had a poor connection on the tach caused lots of emitted RF.

Good luck

[nickwilson159]

Tried running a ground direct to the battery along with a Kenwood KLF-2 DC Line filter, and went so far as to use copper tape to cover the exposed parts of the coil packs. These two actions, at first, eliminated 95% of the noise. The next day, the noise was back and as bad as ever with no changes made - engine temperature, moving vs. standing still, accessories on vs. off, nothing changed or seemed to make any difference. Some days, the noise is almost undetectable, other days it's overwhelming full quieting channels.

Being that the engine (1.5L Turbo "Earth Dreams") is so new, after market coil packs simply don't exist for it yet. The OEM spark plugs are NGK resistor type plugs.

Will try grounding the alternator next and trying a different ground for radio chassis to body. Is it possible that the NMO mount itself may not be properly grounded? That's one part of the installation I haven't focused on since installation.

[flyinace09]

The new Hondas (along with some other manufacturers) are using Direct Cylinder Injection (VW/Audi calls it TFSI, etc) - which means usually the spark plugs needing a LOT hotter spark to ignite - hence the coil-on-plug.

Not too sure with the 2018 CR-Vs, but my 2015 was noise hell with that design - and was the first year for the direct injection engine in the CR-V IIRC.

A DC power filter on the radio helped the most - but UHF especially was always noisy.

[Astro Spectra]

If you did something and the noise went away you need to retrace your steps to discover what changed.

Also a firend found clip on chokes over the injector leads very helpful in fixing his interference issues.

[nickwilson159]

Well, some more testing, and I have a hypothesis now. While parked in the same spot for over 24 hours, engine cold both times, the noise was gone yesterday (75 degrees & cloudy yesterday morning) while it was present today (sunny & 82 degrees late this afternoon). After driving it for a bit, the noise disappeared. Heat seems to be the only common factor - messing with accessories had no effect, and the noise is present on portables as well. I'm wondering if there's a hairline crack in one of the ignition coils that I'm not seeing, or perhaps something on the PCM itself.

Some snooping with a cheap FM radio in the engine compartment yielded noise around the coil packs and the leads to the PCM (to feed the tachometer). Being that the leads to the PCM are buried in split loom and go through a few junction boxes, I figured I'd tackle the ignition coils first. Hitachi just came out with aftermarket ignition coils for this engine - they & Standard/Intermotor/BWD are the only ones offering aftermarket versions, and Hitachi is the only one that actively advertises RFI suppression. While I can't find any reviews on their products specific to RFI, reviews in general on Hitachi coils are very good - seem to be very solid electrically, often exceeding OEM performance. I'll see if they help any.