Ignitioin noise in car radio

I bought a set of sparkplug wires for my V6 3.0L 1995 Lebaron, and I
had only installed 3 of them. I was trying to listen to an AM station
when I was a little out of range, and I heard the squeal of the
engine, with the frequency getting higher as I went faster. I have a
stock Chrysler AM/FM Cassette from about 1995. I had replaced the
rotor and cap, but not any plugs yet.

These are Duralast wires, 30 dollars for a set of 6, NOT the cheapest
that Advance Auto Parts had. Admittedly, I mostly listen to strong
stations I have set my buttons for, but when traveling, I scan the
dial, and I can't remember hearing this squeal for decades.

Are these wires defective and I should return them? Are they too
cheap and I should just figure I wouldn't get good sound on these weak
stations anyhow, and tolerate the squealing when I travel?

I plan to keep the car 3 to 5 more years, but I don't drive that much
and these are probably going to be my last set of wires on this car.

Thanks

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Why didn't you replace the whole set??

Stock Chrysler radios from the '80s on weren't what I'd call very
good, but if adding 3 new plug wires made ignition noise worse,
obviously you bought a cheap set. Duralast is a brand name for crap
sold by big cheapo chains like AutoBone, Advance and others. I use
only Belden wire sets and have had zero leakage or RFI problems with
them for years.

Are you sure you don't have an open capacitor in the alternator's
stator circuit? Many people confuse spark noise with alternator
"squeal" and changing plugs/plug wires won't do a thing about a leaky
alternator circuit. I believe there's a .01 µF capacitor somewhere in
the alternator's stator circuit.

You need to answer if the problem got worse with the new 3 wires, or
was bad previously. "Squeal" that's heard mostly on AM reception, not
the "popping" that changes frequency with engine speed, is usually
alternator RFI caused by the slip rings.

 

Cheap wires don't cut it any more & can in strange situations can cause
check engine lights. Check & make sure it has the correct spark plugs.
Spend the extra money & getthe OEM wires

 

You say you hear a "squeal" in the radio. That's not ignition- ignition
noise is more like a "buzz". A squealing, whistling, or whining sound
that varies with engine speed is usually caused by the fact that the
alternator has "ripple" on its DC output. A capacitor on the output of
the alternator helps suppress the noise, but an inductor and capacitor
on the power line to the radio will pretty much remove it. They sell
these pre-packages as "noise suppressors" at car stereo stores and (at
least they used to) at Radio Shack.

 

Oh, forgot that. Because you have to remove the air cleaner bracket,
I think, to get to the other three, and I haven't had time.

I've bought crap sets before though, and never had noise in my radio.

No, not sure at all, except that I didn't notice this noise before. I
think I should do some more tests, like using the scan button more and
seeing how many weak stations cause this noise. I could even go back
to where I was and try it there and near there. (about 10 miles away,
but a place I don't normally go.)

Hmmm. This noise is a combination of the two. It's squeal that
changes frequency wth engine speed. A fairly high frequency tone,
myabe C above middle C (880 cps?) at 20mph, that increases as I
accelerated, an octave or more.

I guess on a 6-cyl engine at 1000 rpm, that's about 3000 ignitions per
minute. But the fequency of the sound was only about 1000 cps. I
wonder what that means.

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Rat Shack has gotten out of the car audio biz entirely due to high
return rates and lousy product quality of their Chinese imports, not
to mention being run out of the market by schlock merchants like
Wally-Fart. They used to sell a cheesy little L-C filter board that
would do a little filtering, but usually a savvy tech can build a much
better one himself. I generally use a 10 µF electrolytic capacitor
shunted to ground fed by a series 10 mH choke coil I hand wound from
just plain 18 AWG wire wrapped around a soft iron core fed through a
1N4003 diode. The diode provides isolation from the rest of the
electrical system to prevent the cap from discharging through
everything else on the load side of the ignition switch after
shutdown. However, the diode will drop the forward voltage .7 volts,
so that has to be taken into consideration as well. Since most
Chryslers seem to run at a float voltage of 15.0, it's not a problem
at all, although it'll materially cut amplifier capacity slightly.

I know the stock AM/FM radio in my M-body had horrid power filtering
inside, and aside from being AM stereo capable (big deal...who
broadcasts THAT anymore?) was a pretty crappy radio in general. Ditto
the speaker compliment, which I upgraded substantially. I did note a
lot of alternator "squeal" on AM in that unit, but the replacement
Alpine has none, due to better power filtration. I also remember that
the "squeal" dissapated greatly when I turned the slip rings and
installed new brushes. The OP might also want to replace that .01 µF
cap in the stator circuit on his '95, as that will help quite a bit.

Chrysler Corporation was the last domestic OEM customer for
loudspeakers made by Jensen before they folded and the name was sold
to the Japs. 4" X 6" speakers used by the ton by Chrysler cost about
25¢ apiece and performed as such. Although the M-body only has
cutouts in the rear shelf for 4" X 6"s, there's enough room to hog out
a proper 6" X 9" hole to mount good drivers. My M-body has JBLs all
around and rivals any OEM new audio system.

 

No, Middle C is 261.2 Hz. A above Middle C is 440 Hz, which is
International Concert Pitch. Thus, your tone would be up around A
above Concert Pitch. Never screw with a music major on stuff like
this.

Ignition noise sounds more like a "buzz" or "popping." A "squeal" is
almost always caused by arcing from alternator slip rings and diode
switching in the alternator. The basic ripple of a 3 phase alternator
being rectified could be around 1 KHz, though, so I suspect that your
filter capacitor in the alternator stator circuit is shot. As I've
said before, Chrysler radios, at least the ones I've seen since the
'80s, are generally pretty bad anyway. With AM pretty much being a
wasteland occupied by the Mexicans and the right wing fruitcakes,
there's "nothing to see here," as Frank Drebin would say...with a
bullhorn. Still a good source for all-news stations in major markets,
though, although CBS is now screwing that up, as well. The only thing
that MAY save the MW band is HD-Radio, which is now starting to roll
out. Completely incompatible with conventional heterodyne radios,
though.

 

You seem to be unsure if the new wires are truly to blame. That being
the case, rather than chase your tail, it seems to me the immediate
experiment would be to put the old wires back and confirm for sure that
the same problem wasn't there with them under pretty much the same
reception conditions. That at least would preclude 50% of the
what-if'ing that your doing now. That part seems kind of obvious (to me).

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')

 

Tbat's a good idea. Thanks. Today I worked on the motorcycle and
tomorrow it is supposed to rain (but yesterday it was supposed to rain
today), so I'll try it. I think I'll try it one wire at a time.

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Oh, yeah. I remember now.

Well, if I'd known you were reading, I wouldn't have tried this!

This is good. That means the wires didn't make things worse, and that
means the wires are good enough for me.

I'll still check out the weak stations, and go to that other
neighborhood if necessary (don't see how it could be necessary), but
if it is the alternator filter, that's ok. I'm sure it didn't just
happened and this is the first time it has bothered me.

I listen to the Latin stations sometimes, but the right wingers on the
radio really are fruitcakes. It's amazing.

On this occasion, an AM station changed formats and now it's all talk,
but with only female hosts, liberal, conservative, and even Laura
Shlesinger, who is in a category all her own (30% very good advice,
30% average, and 40% terrible some of it enough to ruin a decent
marriage.) That station is what I was trying to hear and I was only a
quarter mile farther from town than my ex-girlfiend, who listens to it
occasionally with no trouble. I didn't remmeber to check the radio
today.

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Trolling are we?

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')

 

Maybe...maybe not. Later, higher voltage ignition systems require
better dielectric and special plug and coil end boots (along with
silicone dielectric grease) to prevent arcing. But from your
description, however, I'm leaning more toward the alternator as the
source.

Bear in mind that most OEM Chrysler (and everyone else, for that
matter) AM sections are generally pretty bad, and have low
sensitivity/selectivity. The one in my M-body would pick up nothing
BUT alternator squeal unless there was a 50KW station to which it was
tuned. Further up the dial in the "local" 1 KW station territory, it
was hard to avoid having the IF stage swamped by alternator noise when
driving in and out of obstructed areas. Going to a better radio
instantly cured that problem. I also put an external "hash" filter on
the battery input the original radio and there was no help...the RFI
generated by the alternator's slip rings and diodes was enough to
screw up the front end on that one. A look inside the radio told the
tale...a DIN-sized aluminum box with only one little board in it!

As HD-Radio increases its presence, the right wingers will go away, as
they will be priced out of the market. Already, Flush Limpdick and
Sean Insanity are disappearing in some major markets (source:
Arbitron) due to poor ratings, and the only reason they're there at
all along with Air America is that air time on AM stations these days
is dirt cheap and they're able to survive by attracting
super-skinflint advertisers. Once wider appeal formats show up on
HD-R (and its tag-along, vestigial AM counterpart), ad card prices
will rise along with ratings, national ad accounts will seek wider
coverage, will drive HD-R ad card prices up, and the "yakkers" be
forced out. Despite all the hubris from right wing loonies, talk
radio of ANY stripe has never been a big money maker for broadcasters
at all. Even "all news" makes more bucks, and that ain't much. The
biggest money makers on AM right now are the latin stations hands
down, even though they typically have "regional" (mid-band) frequency
assignments and limited coverage.

From the looks of things so far, the stations that have cut their
analog bandwidth to 6 KHz and have installed HD-R modulators are
simply simulcasting their AM program on HD-R, and once there are
enough receivers out there, the MW band will go back to music and thus
their ad cards will be competitive price wise with FM, perhaps higher
in metropolitan areas where wide coverage doesn't matter. It doesn't
appear that broadcasters will support two program streams...one for
conventional AM and one for HD-R, although that is certainly
technically feasible. Political shifts in Washington (the FCC) may
have something to say about that later on. Right now, the FCC is
simply a lap dog of the broadcast industry, but things are changing,
as November will show.

The problem here, of course, is that you need a completely different
receiver to decode HD-R signals, just like you do with Sat Rad, which
uses a similar modulation scheme. Look for HD-R MW receivers to start
appearing in new cars probably in the '08 model year, and I sort of
expect Daimler Chrysler to be the first, like they were with the
failed AM Stereo mess. HD-R "add on" receivers, which simply
remodulate the decoded HD-R to an unused FM slot, are out there now,
but aren't very good. Analog/sideband AM will still be available as
well, but don't look for there to be much performance there, making
"DXing" (listening to "skip") nigh impossible in the car, which was a
big fave of mine to do in my cars on long night drives years back. As
with HD-TV, signal coverage area is effectively cut in about
half...digital doesn't "travel well," and won't do "skip" at all due
to synchronization issues. With AM, although there is impulse noise
and adjacent and "skip" channel interference, you can at least get an
intelligible program, although degraded. With digital, once the bit
stream loses sync, it just goes "bye bye."

 

All true, but once you listen to or watch HD for an extended period of
time, you are hooked. You can't go back. I've now got an HDTV at home
and an HD radio in my Dakota, and analog has become just plain
unacceptable. It's like going back to b&w from color, or back to VHS
from DVD.

The other cool thing about HD on FM (like HDTV) is that stations can
simulcast up to two additional discreet stations on the same frequency
along with their primary. So in effect, we can potentially have triple
the number of stations on HD FM than we do on analog FM. Since there
are currently very few HD radio listeners, the HD-2 and HD-3 channels
most stations broadcast have no commercials. If the format is good,
these are HD radio's current gems.

Regards,
Joe

 

Which matters not, because they sold noise suppressors FOR YEARS after
they got out of the stereo business. They started out as an electronics
COMPONENT store anyway, and still have some in the back if you walk past
all the cellular phone crap they have in the front.

 

With AM, although there is impulse noise
But because digital uses heavy forward error correction, it can work at
a signal-to-noise ratio so horrible that if you switched over to AM at
the same signal-to-noise ratio, you couldn't even tell there was a
channel *trying* to get through. It would sound like a dead station.

 

Hey Joe...what make of receiver are you using now?

 

Very true...until it loses sync. Then it's over for awhile. Different
decoders handle resync differently, just like CD and DVD players. In
the end, HD-R will prevail, due to its inherent frequency resue
capability AND its elimination of impulse noise, truncated frequency
response and other ills of old-time analog AM. However, remember
you're trading one set of distortion parameters for another. Like
mp3s, HD-R radio has its own set of annoying distortions.

 

I just bought a JVC KD-HDR1 for my Dakota Club Cab a few weeks ago.
Aside from a few minor quirks, I like it a lot. Crutchfield had it for
$200, free shipping, no sales tax, free antenna and dash adapters. I
don't know that I would've paid the full $300, but I couldn't resist it
for $200. AFAIK, the sale is still going on.

I'm running it through an old Sony XM404EQ (45wRMS/ch x 4) with a pair
of Polk 6-1/2 components in front and Infinity 6-1/2 components in rear.
Except for a slight lack of bottom end (no subwoofer yet), the sound is
nothing short of fabulous.

Regards,
Joe