interference on MW radio in car

[ranj]

Hi

 

Got an issue with my 06 Ford Focus TDCI and just wondered if anyone else has had this same problem.

 

I seem to be getting lots of interferrence when listening to the radio on MW and happens only when the car is turned on. FM, CD is fine. I have standard fit Ford 6000CD system in place.

 

It also affects if I use my mobile or if someone phones me whilst driving, the other person can hear lots of interference, the way its been explained to me is similar to how the interference is when I listen to MW. (btw dont use the phone whilst driving).

 

Its quite funny, it seems like the interference relates to how the sound of the engine/alternater is at that given time, for example if I begin to accelerate the interference gets louder, when I take my foot of the pedal it calms down.

 

Does anyone know what this could be? Really weird problem, it must be some sort of interference which is being generated, I suspect it could be the in car phone system.

 

Any suggestions?

Edited September 23, 2009 by ranj

[SC-UK]

I had exactly the same problem with my Focus!

 

It's something to do with the ignition circuitry on the car (No idea what, not mechanically minded). The accelerator is fly-by-wire and sends and electronic pulse to the engine management system depending on how far down it is pressed, to determine fuelling/throttle etc.

 

A mechanic friend of mine told me of a "something" that can be added to the car to get rid of the interference, but I can't remember what it's called now sorry.

 

Hopefully somebody else will know a little bit more.

 

Tom

[john]

Could be a ground loop isolator perhaps?

[SC-UK]

Could be a ground loop isolator perhaps?

 

It could well be. Sounds familiar, but wouldn't want to stake my life on it!

[john]

I use them when you get a ground loop (hum often found when using powered speakers with HP Laptops plugged in the mains) or anything else that induces that, I get a £4 box from CPC thats an inline one with phono in and out and it shifts it good

[whitenight639]

Its caused by dirty power from your alternator, I remember when i was a kid on the school bus we always had atlantic 252 longwave on and it would always go crackerly when passing under power lines lol.

 

FM is frequency modulation as oppose to AM applitude modulation so its alot less susceptible to RF noise, your interferance could be caused by the grounding on the car or might be from the RF generated by the alternator.

 

if you buy cheap car amplifiers they can whine or buzz too that change with the speed of the alternator, Mine did and i used a beefy high voltage diode out of an old TV between the ground connection on the amp, you can buy proper suppressors and if youve ever fitted a car stereo before you shouldnt have any trouble fitting one, but it might not solve the problem if its RF interferance affecting it, im no expert though, maybe the suppressors fit to the alternator grounding and might stop it?

 

Ask in some Ford owners forums is your best bet.

[SC-UK]

suppressor

 

Well done that man, that's the word I was looking for earlier!

[whitenight639]

Well done that man, that's the word I was looking for earlier!

 

yeh I'm on fire today, i even spelt it right (miracle) haha