Does anyone else get this problem, previously mentioned here?

- When you first start your car on a cool morning, you tune the Rio Car tuner module to an AM radio station on your way to work.

- As the car warms up, you begin to hear a sine wave tone, mixed in with the radio.

- The sine wave tone slowly changes in pitch, cycling from subsonically low, up to hypersonically high, and back down again. This slow cycle happens over a period of a minute or two before repeating.

- The sine wave tone changes in volume depending on how quickly your car warms up. If the car is very cold, the tone doesn't even appear until the car starts to get a little warm. Then as the car begins to warm up, the tone fades in and gets louder. But as the car gets fully warmed up, the tone fades out and eventually goes away.

- The tone is mostly audible on certain AM radio frequencies. For instance, I can hear it really well on AM 1530, but not hardly at all on AM 830. It does not happen at all on FM.

Anyone else had this? I've seen only one report of it (linked above), and it was in another Honda. I'm wondering if maybe it's something specific to my vehicle.

It's happened with two different tuner modules, so I'm pretty sure it's not a fault of the tuner itself.

Maybe there are aliens trying to communicate with Honda's over AM frequencies?

No, I know which frequencies they use, it's not them.

LOL

Maybe it's part of the engine management system sending out a frequency dependent on engine temp. After all it needs to control the mixture depending on this (among other things).

I've experienced it many times. Two different players, two differnent tuners, two different vehicles - one Chevy & one Ford.

I thought it was just the ghost of technology-past telling Tony to stop listening to AM. :)

Bruno

No, I know which frequencies they use, it's not them.

Tee-hee.

Oh, wait. You were serious? (Gulp.)

OK - on a related topic. Today I was driving along and decided to kick in 880 AM (WCBS). The signal strength went clear to the top - great! The sound? Just static. Really loud static (and wailing and gnashing of teeth buried somewhere in there, perhaps near the RDS signal ... wow, perhaps this is an omen or something). In my adjacent Acura Integra - loud and clear, a squeaky clean signal.

Yes, I'm contemplating doing the "experimental placement" of the tuner module again. Just in case ... but I think progress is being made, nonetheless.

I've had this exact problem with my Pioneer 9200R on AM around 1010. So I don't think it's a Rio Car err... Empeg or Mk2a :) problem!

Sounds exactly like an improperly shielded ignition system. The spark coils are computer in the car will adjust the idle in an attempt to warm up the car and it will cycle. The exact frequency that you hear depends on the idle rpm and number of cylinders (firing sequence). RFI leaking from the ignition system will appear on AM.

Calvin

This sounds logical. But the sound does not change depending on engine RPMs. Does that mean anything?

Hmm... It ought to change with rpm. I can't think of another related system that would emit RFI with a sineusoidal pattern except the ignition system though.

Calvin

After upgrading to 2b7, I left my empeg playing in my room, lined in to my stereo. After a while, I noticed a sine wave, as mentioned herre. Sounded like it coincided with something inside the player. Don't think it was the hard drive, which was my first guess.

Anyhow, left it off for several hours and it stopped. It still does it when very hot, so I'm thinking there may be a fan in there or something.

Could this be what we are experiencing?

Those cars with better ventilation in the dash would get it less and stuff.

I did not experience it with 1.3, but then I didn't really put it through it paces as much :)

I'm probably crapping on about nothing, but I thought it might be a valid point....

Sounded like it coincided with something inside the player. Don't think it was the hard drive, which was my first guess.

Seeing this comment got my attention... A while back I had noticed an odd noise occasionally when listening to one of my AM stations (610 kHz AM.) The thing is the noise only happened when I would hit the button which allows you to change to a specific frequency by typing in the numbers... You know, where the little Frequency dialog pops up. I think the Search button on the remote pops that up. Anyway, you guys sound like you're getting this kind of noise in other circumstances too, but since you said it sounds like something the player is doing, maybe you can try to use that button and see if it causes any noises.

In my car, as soon as I'd hit the search button, the really loud whiny noise would come on, and stop after about 20 seconds or so. Only on AM radio, and only on that one station. It's indeed strange behavior so I figured I'd mention it here.

Goughchr, your description sounds more like a ground loop. The sound I'm getting only happens on AM radio, and only on certain frequencies..

I've never heard from anyone ever having a ground loop problem in the home. Other problems yes, but not a loop.

And Tony, you're sure your problem eventually goes away completely? Or is it just harder to hear because of the content at the time?

Moving the tuner (moving it around actually) if it was easily accessible would be one easy troubleshooting step.

Bruno

And Tony, you're sure your problem eventually goes away completely? Or is it just harder to hear because of the content at the time?

Certain. It fades in over a period of about 3-5 minutes, then fades out over a period of about 3-5 minutes. At its peak, it is ear-splittingly loud, drowning out the program content.

How quickly it fades in and out seems to be dependent upon how cold it is that day. If it's very cold outside it takes a long time to fade in and out. On a warm day it's very quick.

Do you have the heater (any climate control unit) running in the car during this cycle?

Bruno

You're already in California... But could try moving a little farther South... :)

Do you have the heater (any climate control unit) running in the car during this cycle?

Of course. Like I said, it happens on cold mornings, as things warm up. But the sound does not change if I turn off the heater.

Like I said: Are you sure it's not coming from the engine management system. Maybe there is a voltage controlled oscillator (or similar) in there. Maybe something to do with the cold starting/running system. As the engine warms up, the frequency of oscillation increases.
Just a theory.

edit: Just re-read your initial post. So the pitch goes up and down a couple of times. Hmmm... How about this: Engine starts off cold so the frequency is low. As the engine heats up the frequency increases until the engine is warm enough to open the Thermostat. Cold water then flows around the engine and cools it. The frequency decreases again. The Engine then continues to heat up and the frequency increases again until it gets out of your hearing range.

Interesting ideas. If this were the cause, how would I go about solving it?

Do you have any thick lead panels to play with? Perhaps one of those bibs they use at the dentist when taking X-rays?

If it is something like was just discussed, I would think that you should be able to affect the sound by moving the tuner around. If you wanted to be extremely diligent, you could also hook up an extension lead and move the tuner very far away (as a test of course) - or out of the car.

Bruno

Do you have any thick lead panels to play with? Perhaps one of those bibs they use at the dentist when taking X-rays?

Lead? Does Tony drive a nuclear-powered car, or do engine management systems routinely produce gamma or hard X-rays?

$Deity only knows!!! If this is the culprit we still don't know whether the interference is being transmitted through the casing or whether it's using the attached wires as antennae. You could get a portable radio tuned in to your problem frequency and move it around the engine compartment to see if the signal strength changes. If you have access to an Oscilloscope I suppose you could check the wires out to see if they're carrying the signal too. Maybe try disconnecting the temp sensor (there may be more than one though) and see if this changes anything. If you find the management system (or any other system for that matter) to be the instigator you might be able to fit some kind of notch filter or something. There's not much point in speculating too much until we know whether it's this or not. Anyway whatever it is I hope you can get it sorted easily. Let us know how you get on.

Well, the nuclear-powered car is the other one. The empeg's in my daily driver, so that's not it.

I think my first step is to dismantle the dash and try repositioning the tuner module. Not sure when I'll get around to that.

I like the idea of checking with the portable AM radio, I might try that.

I think I'd have just as easy a time of finding lead panels around the house as I would a portable AM radio. :)

The bib trick would work, really, I swear. Some people might suggest tin-foil, but that's to prevent brain-readings by the aliens Tony was talking about earlier in the thread.

If the noise is being introduced into the signal wires from the tuner module to the empeg, then moving the tuner isn't likely to do any good. But if this were the case, I'm sure more people would be having this problem - and with other frequency selections. Since it seems to be specific to certain frequencies, this points to interference being picked up by the tuner itself (or the antenna line I suppose).

Bruno

Some people might suggest tin-foil, but that's to prevent brain-readings by the aliens Tony was talking about earlier in the thread.

Everyone knows that's just a joke.

It doesn't work because their mind rays are much more powerful than that.