I replaced the factory radio in my 2005 Elantra with an aftermarket Kenwood unit, mainly because of the lacking performance of the tuner on the Hyundai stereo. To my dismay, the Kenwood has the exact same issues- when the car is moving the reception is horrible. Lots of distortion, and noise- and at first all the basics were checked: antenna, coaxial cable, and the the radio itself replaced. the Kenwood has a very good FM tuner, and I've listened to this exact same radio model installed in a Toyota and it has superb signal pickup.

Here's why I think it's the vehicle computer generating noise: when the car is off in the accessory position, the noise vanishes and the reception is clear. when turning the key to the start position WITHOUT the engine running (but activating the car's computer) the noise floor increases and the reception on FM is impaired.

I've gone rounds with my dealer, they now blame the aftermarket radio, yet the SAME problem occured with the FACTORY unit. I am ready to put it back in and take it back up there to show the exact same problem exists with the OEM radio. There is obviously something in the car generating RF interference and it occurs only when the vehicle is in the running position regardless of the engine being on (thus ruling out spark plug or ignition related problems)

I'd really like to get this resolved, anyone ever dealt with this issue before?

This post has been edited by MrFlashport: Sep 18 2007, 01:30 AM

Try an in-line noise filter perhaps?

^^Yep. A filter will block it for you. Your head unit's FM tuner is picking up engine noise from your car when you are accelerating.

I would buy the ignition noise problem, however when the engine is OFF, the noise instantly appears when you turn the key to the position just before the START position (you know, when all the dash lights come on and the engine computer is energized) thus leading me to believe it is not an engine noise problem but RFI from the computer which is located near the radio itself. I've tried chokes on the power leads, no change. The noise simply disappears when the car is off (but the radio energized if you have the key turned to the ACCY position)

Also, the type of interference sounds like computer clock noise, not the typical impulse noise common to automotive ignition systems or spark plugs. I've installed mobile FM two-way radios for over 15 years, very familiar with that type of sound. This is clearly computer clock noises.

It's really starting to **** me off. I'm a two-way radio technician and work on RF emitting devices for a living. I've also noticed that the computer generates alot of trash all throughout the VHF and UHF spectrum- I haven't had time to checkout a spectrum analyzer or service monitor from work, but I've also noticed strange heterodyne sounds on my VHF and 800MHz analog portables I carry for work. Same thing, when the car's computer is OFF the interference magically stops.

I hate to waste time with this but it really detracts from an otherwise fine car. It just isn't if your a radio guy like me- the **** thing is full of RF hash. I guess I'll put my spectrum analyzer in the car and run some tests. This should prove interesting.

Will certainly be keen to see the results.
In the meantime, I'd be wearing lead underwear, just to be on the safe side :P

well after riding around for a week with an IFR-1500B communication service monitor, I can truly say that the little black box behind the dash is nothing but a wideband RF noisemaker. This thing is truly in violation of part 15 of FCC rules. That explains the RF noise and poor radio reception. I currently put in an Eclipse CD-1000, an entry level unit that deals with the noise better than anything so far, it's at least tolerable. And I like the looks of the unit, black face,very clean design- plays MP3's and WMA's. I have a Kenwood MP3 unit (Hyundai branded) silver face in mint shape I'll probably list on Ebay- it's a great unit just not in this car.

as far as the horrific RFI, Hyundai USA basically told me to get bent. We'll see what the FCC says, I've got a friend in the Atlanta field office I've dealt with in the past with work stuff, he's going to put me in touch with someone at the FCC OET- not trying to make a mountain out of this, but the computer in there is a source of RFI from around 38MHz as high as 960MHz, with spurs and hash all over the place, some of them are strong enough (around -55dbM) in the 880MHz region to interfere with my at&t GSM cell (which operates on the B band here in most of the ATL), this is with the phone in the cup holder- no wonder the "all over" network isn't "all over" inside my Elantra! Seriously, if their computers are so poorly shielded it causes interference to licensed radio services such as part 80 cellular and part 90 stuff, there's a problem.

Well thought I'd share this with anyone having similar issues. Get an Eclipse radio if you want good FM. Why does this seem to be a theme in Hyundais? Great cars, cheap audio systems and funny problems like this RFI? I had a 2003 Camry for a while, the factory audio system (made by Panasonic's parent, Matsushita) sounded AWESOME, no RFI to anything with the engine running...I hated to sell it (was my mom's ride, she passed away in 06 from cancer RIP...too many memories) but it sounds like it was more "electronically friendly" than my 05 Elantra.