Engine Noise through stereo

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Shane

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Heres a question for the stereo guys.

I got a cd player deck in my car, and I seem to be getting ALOT of engine noise when listening to the radio only.

Is this bad ground? or caused by the cheap antenna I bought?

any ideas where to start to fix this?

Thanks

Shane
 
Are you using resistor spark plugs and RF suppression plug wires? If you are and still have the problem, go to Radio Shack and get a 10 Henry choke. It will have 2 leads. Splice it into the power wire for the radio so that all the current for the radio runs through the choke. That should take care of the radio noise.
 
car audio forums be good for this

how old is player?


power cables and signal cables seperated?

they must

noise will transfer

cd bracket and ground must be in diff locations

antenna isnt the problem

depends how your running your power leads from or were too
batterY?
fuse block?
 
If it comes through the radio only (not the cd) it has to be coming in on the antenna and no inline power filter will have an affect unless the radio design is as such that the radio section is totally isolated inside from the CD section. Very few are designed like that. A high performance ignition such as a Mallory or MSD multi spark box can magnify interference since the spark energy is so much higher and many more times per cycle than a stock ignition. If you have solid core or very low resistance plug wires that's another strike against you.

Resistor spark plugs do very little to stop radio interference in spite of being advertised as such since the beginning of time. Spark plug wires have a much greater affect on RFI (radio frequency interference).

The antenna usually doesn't cause a problem unless the coax cable is super cheap. The proper length for a FM antenna shaft at 98 MHz (center of the band) is 29". If it's not somewhere between 26 and 32.5" it may not be resonant on the FM band which can allow greater interference.

A side note: To optimize your radio listening follow this rule of thumb. If you mostly listen to stations lower than 98 MHz use a whip in the 29-32.5" range. If you listen mostly to stations above 98 MHz use a whip in the range of 26-29" length.

One last thing to check is to make sure the ground strap from the engine block to the firewall is in good shape. If not it's like having a spark generator under the hood. When the engine is grounded good to the fire wall it can help kill off the spark generator affect.
 
alright thanks!

alot of good info for me to look into there!

I will check it out this week, and let you know what/if anything solves my problem!

thanks

Shane
 
Shane said:
Oh, and I am running MSD box, and the red 8mm msd plug wires, with ngk plugs..
Click to expand...

The plugs should be fine. I always run NGK's and have not RFI problems. Check the wires and see what they are. If their the solid core or spiral core (big gimmick) they may be the major problem.
 
I have found the power line filter to be the best way to go, when it's needed.
 
Power line filters are helpful but never underestimate the value of using a very heavy ground strap and making a solid, clean connection to the firewall. Poor ground connections are always a major nuisance in any electrical application (automotive or otherwise) and they are frequently overlooked. A wide, flexible braided strap should always improve the situation.

The spark plugs generate AC noise from DC-20 MHz, just like lightning in the sky. The heavier the ground strap, the lower its inductance (and resistance). The lower the inductance, the more effectively the noise is grounded to the return path (back to the battery).

Inductance is not measured with an ohm meter but it effectively creates resistance as frequency (ie: AC) is increased. Resistance is not dependent upon frequency so simply connecting a wire will not always guarantee a good ground.

Sorry, but you have an electrical engineer here...:snakeman: It is not as painful or complicated as it sounds but physics is not always easily explained. :evil2:
 
Claudius said:
Power line filters are helpful but never underestimate the value of using a very heavy ground strap and making a solid, clean connection to the firewall. Poor ground connections are always a major nuisance in any electrical application (automotive or otherwise) and they are frequently overlooked. A wide, flexible braided strap should always improve the situation.

The spark plugs generate AC noise from DC-20 MHz, just like lightning in the sky. The heavier the ground strap, the lower its inductance (and resistance). The lower the inductance, the more effectively the noise is grounded to the return path (back to the battery).

Inductance is not measured with an ohm meter but it effectively creates resistance as frequency (ie: AC) is increased. Resistance is not dependent upon frequency so simply connecting a wire will not always guarantee a good ground.

Sorry, but you have an electrical engineer here...:snakeman: It is not as painful or complicated as it sounds but physics is not always easily explained. :evil2:
Click to expand...

Very good but don't forget RFI as a point of interference introduction. In his first post he said it only comes through the radio. Sounds like that would be introduced through the antenna, instead of the power line. I'm a amateur radio operator (call sign KB9VXQ) and have been in on chasing interference quite a bit whether it be automotive or high tension power lines. I was also an electronics major in college.
 
Your point is valid and my solution was from an actual application where a new radio was installed into a gas vehicle that never had one previously. Noise only came through the radio when the engine was running. When the engine was stopped, the noise was gone when the radio was operating.

You are correct in that the RFI is likely coming into the radio via the antenna. I should have stated that the spark plugs were introducing the noise over the air, not through the power line. I apologize for not stating what was the obvious.

Just the same, the original ground wire was too inductive, causing the radio's reference plane to "float" and the change to the heavy ground strap fixed the problem instantly. Internal to the radio, it is my suspicion that the noisy ground plane is polluting the receiver's oscillator circuits. I have fought this battle several times as a radio designer.

At least there are several possibilities to try out.

fishy68 said:
Very good but don't forget RFI as a point of interference introduction. In his first post he said it only comes through the radio. Sounds like that would be introduced through the antenna, instead of the power line. I'm a amateur radio operator (call sign KB9VXQ) and have been in on chasing interference quite a bit whether it be automotive or high tension power lines. I was also an electronics major in college.
Click to expand...
 
What I find funny is that I had mega engine noise in my aftermarket stereo on my 1992 Olds Cutlass Coupe, but zero when I installed my new system in my Dart...go figure...LOL.

CD player
2 - Pioneer 6x9s
1 - JL 10W3V2 subwoofer
1 - Kenwood 1200w 5 channel amp
 
superdart said:
What I find funny is that I had mega engine noise in my aftermarket stereo on my 1992 Olds Cutlass Coupe, but zero when I installed my new system in my Dart...go figure...LOL.

CD player
2 - Pioneer 6x9s
1 - JL 10W3V2 subwoofer
1 - Kenwood 1200w 5 channel amp
Click to expand...

Doesn't surprise me. The problem in the Olds was possibly either the electric fuel pump or electric fan, or both. Both are known to cause noise. Fuel injectors can even cause noise. The electric fan on my old Dakota caused alot of noise and a filter at the power input of the stereo didn't kill it all. I finally made up a choke/capacitor filter and installed it as close to the fan motor as I could get it and it completely stopped the noise. The parts were very specific I remember. I tried several different capacitors and chokes until I found what worked. If I would have had an oscilloscope I could have figured it out alot quicker but....
 
I didn't catch the nature of the engine noise you're experiencing. If it is a whine or a howl, it is being generated by the alternator. If it is a ticking noise, it is coming from the ignition system. I think the ignition issues are being covered well.

Back in the day, guys used to put choke coils on the antenna leads to get rid of the whine. I had alternator problem with the 73. Digging around my junk (as my ex- used to call it), I came up with a biggie about the size of a frozen OJ can. I plugged it in and ended the problem. I'd tell you more about it if I could but there are no identifying marks or labels on it. It looks like a silver OJ can with a short antenna lead coming out of one end and an antenna lead socket on the other.
 
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