07 Dodge Charger ignition RFI wipes out VHF MCS2000

007 · Post by **007** » Thu Oct 04, 2007 8:27 pm

Gang-

Just did a civvie '07 Dodge Charger V8 over the weekend for a VFD member, but there is a boatload of RFI getting into the 110w VHF MCS2000 we put into the car. The VHF antenna system is a Motorola NMO kit with a 1/4w on the rear decklid, with the MCS tray mounted in the trunk. There is also an 800 MHz MCS2000 in the vehicle with no issues whatsoever.

When the car is running, there is constant RFI on received signals that disappears when the vehicle is turned off. We added a ground wire from the decklid to body, which helped a little but the RFI still there. I'm going to ground the hood next, but where else should I be looking on these new Dodges?

Is this a V8 only thing?

FireCpt809 · Post by **FireCpt809** » Fri Oct 05, 2007 6:40 am

Where is the radio grounded? I would make sure that it is directly to the battery -. Also Keep the try to keep the coax as short as possible.

tvsjr · Post by **tvsjr** » Fri Oct 05, 2007 7:44 pm

FireCpt809 wrote:Where is the radio grounded? I would make sure that it is directly to the battery -. Also Keep the try to keep the coax as short as possible.

BAD IDEA to ground straight to the battery. If the ground straps from the battery to the car frame fail, the juice will find another path - through the radio, out the coax. When you go to crank the vehicle, Bad Things will happen. DO NOT ground directly to the battery unless you fuse it properly and understand the risks.

thebigphish · Post by **thebigphish** » Fri Oct 05, 2007 11:14 pm

I second that. Creating alternative pathways for the full force of a car battery is asking for disaster. Only time i ever go to a battery directly with the black is when i am trying to diagnose a bad radio. That's IT.

007 · Post by **007** » Sat Oct 06, 2007 9:16 am

First, the radio is grounded straight to a chassis ground in the trunk, which is only a few inches away from the battery ground since the LX platform has the battery in the spare tire well.

Second, I am well aware that you do not ground direct to the battery, thru a fuse no less...both are no-no's. FireCpt809, there is a reason LMR radios only have a few foot ground wire with no fuse. Terry covered the high points in his post above.

Third, it appears the Hemi's coil-over-plug ignition is the culprit, but until I can play with grounding some more things I don't know if I can make the noise go away completely.

FireCpt809 · Post by **FireCpt809** » Sat Oct 06, 2007 3:15 pm

I was half awake when I posted that. I was trying to say to try run a ground to the battery to see if that would decrease the noise.

007 · Post by **007** » Sat Oct 06, 2007 7:55 pm

FireCpt809 wrote:I was half awake when I posted that. I was trying to say to try run a ground to the battery to see if that would decrease the noise.

No problem

I will and see what the score is with that...but I'm not holding my breath.

Einstein · Post by **Einstein** » Sun Oct 07, 2007 3:38 am

You might try an elevated feed antenna insted of the 1/4 wave.

Jim202 · Post by **Jim202** » Sun Oct 07, 2007 4:52 am

Not trying to be a pain, but just what does this RFI noise sound like. There has been a
number of comments on here, but it would help if you could try to identify just what
the noise is your talking about.

Is it a popping kind of noise that changes with engine speed?

Is it a whine kind of noise that changes tone with engine speed?

Is it a raspy static type noise that changes tone with you heater fan speed?

Is it a raspy static that is there when you first turn on the ignition key, but don't
start the engine and then it goes away?

Is the noise there only when the vehicle is moving and not there when stationary?

Do you hear any of this noise if you turn the vehicle radio onto the AM band?

Just a slight hint might allow comments to focus on the area where to look in trying
to solve your problem.

Jim

007 wrote:Gang-

Just did a civvie '07 Dodge Charger V8 over the weekend for a VFD member, but there is a boatload of RFI getting into the 110w VHF MCS2000 we put into the car.

When the car is running, there is constant RFI on received signals that disappears when the vehicle is turned off.

Is this a V8 only thing?

KE9GK · Post by **KE9GK** » Sun Oct 07, 2007 10:40 pm

To answer your question Jim (because it may or may not be my vehicle that is in question here

) the sound is a cross b/w a very slight raspy buzz with the most pronounced problem being a large amount of popping that changes ever so slightly with the engine RPM's. It is there all the time as long as the engine is running, and is also present on my VHF XTS3000 portable as well when I have it in the vehicle....which confirms that it is some sort of ignition noise and not electrical. This same noise is NOT present on my transmitted signal. In fact, I have been complimented on the radio's audio and signal charachteristics by the users on the other end of the mic. I have absolutely no problems with the AM band on my car radio..in fact it sounds great, nor is there an issue on the 800 MHz MCS that is installed in the vehicle which uses a glass mount 800 antenna. This RFI is so severe that it is actually de-sensing the receiver on the VHF radio....on both the portable and mobile. We are about at our witts end here.....the decklid ground helped considerably with the receive (as in the radio actually hears things now) but the RFI seems to be so strong that it is attenuating weaker signals..which goes without saying is bad..especially in a public safety setting!

Any help would be appreciated!

Thanks Gang

Oh Yeah...PS....before anyone asks, the antenna is center mounted in the decklid with the feedline running through the bracing on the underside of that decklid down through the stock rubber wire conduit and into the trunk area. There are no coax pinch points and there is no excess cable coiled up..it is just long enough to reach the radio (my guess about 6-7 feet total)

Post by **bobbyaa** » Mon Oct 08, 2007 1:47 am

It almost sounds like a leaky coax type situation where instead of picking up and "conveying" the signals from radio transmissions...its doing it with the rfi. Try a frequency counter while the vehicle is running and see if it is at a specific frequency. If so you can get a filter to handle the problem.

agtkgv · Post by **agtkgv** » Tue Oct 09, 2007 10:20 am

Have you tried a more shielded coax?

Einstein · Post by **Einstein** » Tue Oct 09, 2007 10:37 am

This may be a stupid question, but are you in the same location when this occurs or is it the same when mobile?
Check the interference with a spectrum analyzer. See if it is the vehicles computer. I know at one time Ford had different part numbers for different computer clock freq's for just such problems at freq's near the interference.

HLA · Post by **HLA** » Tue Oct 09, 2007 5:00 pm

i've installed vhf cm300's and vhf cdm1250's in a couple dozen chargers and never had any noise problems and those radios are not even close to the quality of a mcs. especially if you have the drawer in the trunk. do you have a vhf portable to move around in a few places in the vehicle to see if it does it? one other thing is unplug the head and move it back away from the engine and see if it goes away. and lastly unplug the antennae all togather and see if it goes away and maybe if you have a magnet mount see what happens when you move it up on the roof.

KE9GK · Post by **KE9GK** » Tue Oct 09, 2007 8:58 pm

Thanks Everyone for the insight. HLA I get the same RFI on my XTS3000 when its in...or for that matter even near the car and its running. Is there something different in the police package cars vs the civies as far as grounding is concerned? I will try the mag mount antenna idea and let you know what happens. Keep the ideas comming!!

Thanks!

Jim202 · Post by **Jim202** » Wed Oct 10, 2007 3:47 am

Guess my last message didn't get posted.

Have you tried using more than one frequency? The digital clock in some of the vehicles today are a
big signal generator and will almost blank out certain channels on a VHF radio.

Have you tried just turning on the ignition key without starting the engine. The electric fuel pump is
also a big noise generator. After a few seconds with the engine off, it will shut down. If the noise
comes and goes this way, you will need to filter the fuel pump power right at the tank.

Some of the new electronic dash instrument clusters are also a noise generator. This is not an easy
thing to prove.

Try a few tests and let us know how you make out.

Jim

KE9GK wrote:Thanks Everyone for the insight. HLA I get the same RFI on my XTS3000 when its in...or for that matter even near the car and its running. Is there something different in the police package cars vs the civies as far as grounding is concerned? I will try the mag mount antenna idea and let you know what happens. Keep the ideas comming!!

Thanks!

007 · Post by **007** » Sat Oct 13, 2007 10:11 pm

We've tried a dozen different things and it's still there...no amount of grounding or ground strap helps, mag mount gets same to worse noise level all over the vehicle, etc.

Noise is only present when running, and within 10 feet of the vehicle...mainly in the front, as there is null to the rear about 10 feet behind the vehicle.

The noise is being generated by something under the hood in the VHF-high spectrum (140's into 160's) and is being received over the air by antenna, not through wiring or coax.

Jim202 · Post by **Jim202** » Sun Oct 14, 2007 11:17 am

Ok let's calm down. You said you tried a dozen things and it's still there. You have been given a number of
things to try. You answer is not very much help for the rest of us trying to help you. Could you explain
the different things you have tried with no results.

One was to just turn on the ignition key and see if the fuel pump was making the noise. You statement
of it's only there when the engine is running doesn't help us. Did you or did you not do the fuel pump test?

Did you try pulling the fuse for the heater fan motor? Not sure on that model, but on many vehicles this
motor runs at low speed even if you have it shut off.

An extreme measure to try is to lift the control wire and heavy current wire off the alternator. This will
take that unit out of the picture as a noise generator when the engine is running. Just remember to
connect it back up.

Have you tried to clean the battery posts? I have seen some of the new vehicles come through with
poor or dirty connections between the battery posts and the battery. Before you pull the terminals off,
take a digital voltmeter and measure the battery voltage and then put you meter leads on the battery
connections going to the vehicle (not the battery itself). While the engine is running, turn on the headlights
and again measure the voltage. Turn on the high beams, measure again. Turn on the AC and measure the
voltage again. What your looking for is a drop in voltage with the load. If the voltage stay up around 13.8
to 14.5 volts your good. If it starts to drop off, you may have a problem with the alternator.

While your looking at the voltage with the meter, put the meter in the AC voltage mode and low range.
Trying to see if you have any AC on the alternator output. This could point to a bad diode in it or poor
connections. You should not see more that about 50 millivolts or so. Much above this could point to
an alternator issue also.

Calm down and let us know exactly just what steps you have tried.

Jim

007 wrote:We've tried a dozen different things and it's still there...no amount of grounding or ground strap helps, mag mount gets same to worse noise level all over the vehicle, etc.

Noise is only present when running, and within 10 feet of the vehicle...mainly in the front, as there is null to the rear about 10 feet behind the vehicle.

The noise is being generated by something under the hood in the VHF-high spectrum (140's into 160's) and is being received over the air by antenna, not through wiring or coax.

KE9GK · Post by **KE9GK** » Sun Oct 14, 2007 10:10 pm

OK...

The fuel pump is not the issue, there is absolutely NO noise on the radio when the key is in the ON position and the engine is not running. I have tried listening when the key is initially turned on - NADA! Cycling through the fan speeds do not cause the noise to be heard on the radio when the car is not running, nor does it change the sound when the engine is running. Power was removed from the blower motor completely - no change in the sound. Now....as far as the electrical system goes...the noise is definately NOT alternator whine...it is most definately ignition!! However, the first thing that we did was to clean the terminal posts on the battery which were NOT dirty (the car has 2500 miles on it). Next, as far as the alternator noise goes - I went through all the tests that you advised as far as voltage drop etc. go - NO PROBLEMS (I was a mechanic at ford for quite a few years - very aware of electrical noise issues on the Crown Vic PI's). Again, I need to remind our readers that the same RFI is present on my XTS3000 handie talkie when the car is running and I am in or within 10' of the car! Oh yeah...the noise does change ever so slightly with engine speed - the popping bacon fry sound gets only slightly faster..but that is the extent of the changes!

007 and I have grounded the hood, trunk and cleaned up the grounds from the block to the strut mounts, (chassis) and from the battery to the chassis in the trunk with no change. We then grounded all the trays in the trunk both directly to the battery, and then to the chassis with no change in the RFI. We then made a "test jumper" and started randomly grounding "suspect" components under the hood while the engine was running - there was some popping heard on the radio as the block was grounded and un grounded - but the noise never improved or was reduced. Next, we took a mag mount larsen base with a 1/4 wave antenna and placed it on different parts of the car. The noise got worse when the antenna was placed on the rear 1/4 panels (regardless of which side), the noise was about the same when placed on the trunk near the stationary drilled NMO mount, and the noise was the worst when the base was placed on the center of the roof. We then tried a 5/8 wave antenna on both the stationary mount and the mag mount with no change on the RX signal. We were able to almost eliminate the noise when we placed the mag mount on the underside of the decklid while it was open - horizontally polarizing the antenna and using the decklid as an RF shield from the engine. The other time we were able to eliminate the noise was when we pulled the mag mount off the car completely and walked about 5' behind the vehicle.

So...I hope this was a little more thorough than 007's post....we are still as frustrated as he conveyed in his last post...but as you can now see it is for good reason, and we did try about a dozen things!

So I will now end this on a more positive note...H E L P !!!

Post by **alex** » Mon Oct 15, 2007 11:13 am

Have you tried another VHF MCS2000, or another mobile radio to see if the sound remains constant?

-Alex

HLA · Post by **HLA** » Thu Oct 18, 2007 6:51 pm

what frequency is making the noise? i have a 06 charger in the shop right now, i'll program it and see what happens. right now the cdm in it is totally quiet on all frequencies. or is it all frequencies while recieving or is it just noise thru the speaker even while squelched.

KE9GK · Post by **KE9GK** » Fri Oct 19, 2007 7:33 pm

The noise is on the entire VHF band, not only on speciffic freqs......only on the received carrier that causes the unit to unsquelch. The noise is not there all the time..only when the radio receives a signal.

Alex - as far as trying another radio....I haven't done that yet...although with the noise being on my HT as well I am not overly optomistic.

Thanks again gang!

Einstein · Post by **Einstein** » Sat Oct 20, 2007 2:20 am

The front end might be getting overloaded. Try a bandpass cavity, see if any of the interference goes away.

Post by **gumbo** » Tue Nov 06, 2007 8:06 pm

*A thought from a car guy that just dabbles in VHF stuff*

I assume this is a 5.7L Hemi V8? These should have 2 spark plugs per cylinder for a total of 16. there is a coil on plug configuration for one plug on each cylinder..... the other plug is fed via a spark plug wire on a nother cylinder's coil.

I would consider trying a set of high performance RFI suppresion wires. RFI can significantly hinder the operation of aftermarket ignition boxes such as MSD's...

I'd see if I could get a set of Spiral Core RFI suppression wires.

http://store.summitracing.com/partdetai ... toview=sku

Those fit a Dodge Ram with a Hemi, I'd call MSD to see if they fit a Charge, I couldn't find a specific set.

KE9GK · Post by **KE9GK** » Wed Nov 07, 2007 11:22 am

Thanks for the info! However, there are no spark plug wires on a Charger's Hemi engine....only coil packs on the valve covers (unless they are hiding the wires under the valve covers)....believe me that would have been the first thing I'd have checked!!

Thanks.....and yes it is STILL there!!h

kossuth · Post by **kossuth** » Wed Nov 14, 2007 9:33 am

Well, coming in on the backside of this I'm gonna ask a few questions. Is the noise coming from a device directly (IE alternator) or is it being injected into the ground of the vehicle from a device? If the noise is all encompassing I am tending to think something is putting a hmm which just happens to mimic your radio frequency. Those hmm's typically come from bad grounds. Other than the 800 mhz radio is there anything else aftermarket that's installed in this vehicle? IE sound system or performance parts ect ect. If the noise goes up with engine speed I would tend to think that the source is one of three things. It's your ignition, it's your alternator, or it's your fuel injectors/PCM (not sure how Chysler has the EFI setup whether the PCM switches the hot or the ground to the injectors). The alternator is a quick easy check. Just pull the serpentine belt off the motor real quick and fire the car up for a minute (running for a minute or less won't hurt it) and see if the noise goes away. If the noise stays then I'd be looking for the grounding point for the coil packs/fuel injectors/PCM. There's a good chance they are grounded to the same spot. I'd then ensure the ground is good and tight, and possibly consider running a strap to the sub frame of the car to the grounding point if said point is a stud on the vehicle firewall. I'm sure it's something simple, you're just gonna have to do a process of elimination.

007 · Post by **007** » Thu Nov 15, 2007 10:14 am

The noise is all encompassing, and is wireless...it is present on all VHF portables within 10 feet of the vehicle, with a null to the rear. We've tried adding ground straps in various places and cleaned/tightened all OE grounds. The car is stock other than the radios and SmartSiren.

We are trying to get part numbers from Dodge to see if ignition parts are different on the hemi police vehicles.

kossuth · Post by **kossuth** » Thu Nov 15, 2007 11:34 am

I'd still try pulling the alternator belt off being it isn't a whole bunch of trouble just to see. I have a hard time believing that a noise like that just part of the "CIVI" chargers. I'd check it and see. A co-worker of mine has a Magnum with the Hemi with VHF/UHF/HF ham rigs in it with no issues.

007 · Post by **007** » Thu Nov 15, 2007 5:06 pm

Yeah, you'd think it would be on all of 'em but the owner went to a dealer with his XTS3k and all the '07 Hemi LX platform cars on the lot had the same noise...but the two Hemi Charger po-po cars I have access to do not have any RFI whatsoever.

It's weird.

kossuth · Post by **kossuth** » Fri Nov 16, 2007 5:07 am

Wow, if that is indeed the case then lord knows what's different. Could be the PCM, could be just the coil packs, could be just grounding cables, and so on and so forth you get the idea. I'd almost just want to get the dealer involved and try to get some answers from somebody at Dodge about this. Because if what you are saying is true you might go around and around trying to fix this issue and never truely figure out what's causing it. If something is different in the electronics of the Civi vs POPO package Charger somebody at Dodge knows what the difference is. Good luck with this one.

High_order1 · Post by **High_order1** » Tue Nov 20, 2007 8:58 pm

I tried posting this once but the forum ate my idea. This might be stupid, but have you considered doing this: Take your VHF portable, put it on a conventional frequency somewhere in the middle of the band, unscrew the antenna to deafen the front end, unsquelch it and use it like a detector under the hood. You could even consider wrapping the radio with foil a couple times to further desense the radio. Just a thought. If you can narrow it down, it makes it easier to solve.

-Shawn

abbylind · Post by **abbylind** » Wed Nov 21, 2007 6:03 pm

Had the same problem with a few PD cars. Found it was the ignition wires each time (one time it was the plugs) Put in supressed wires and resistor plugs. Fixed the problem. You might also check the ground from the engine to the chassis.
I used a length of coiled coax on a stick plugged into the radio to "sniff" out the source. Probed around the engine area and found the ignition wires were the culprit. You might also check the dealer to see if they have any manufactuer bulletins on ignition problems with that particular model.
Good luck

Fowler

KE9GK · Post by **KE9GK** » Sat Nov 24, 2007 3:52 pm

THANK GOD....SOMEONE FINALLY HAD THE SAME PROBLEMS!!!!

Fowler I will check again and see what I can come up with, but I dont see any plug wires on the car anywhere

abbylind · Post by **abbylind** » Sun Nov 25, 2007 1:27 pm

Pull the spark plugs and make sure there aren't any cracks in the ceramic portions. A hairline crack will spew out RFI. Also check all connections on the high current side (coil wires) you may end up replacing the high current wires. An old trick was to crack the hood (make sure its dark under he hood, no lights) and look for some arcing on the high current side.
Your problem is RFI leaking from the high current circuit use the coiled coax to sniff it out.

Fowler

abbylind · Post by **abbylind** » Sun Nov 25, 2007 1:39 pm

Oh forgot to add if the car has a "Splitfire" type sparkplugs they are notorious for producing RFI. Try an OEM resistor or suppressed type plug.
Fowler

Post by **mrkawliga** » Sun Dec 09, 2007 1:29 pm

Hello,

Has there been any update or resolution to this problem. I have had the exact same problem however it is on a police package 07 Charger with the Hemi engine. I have done many of the same tests mentioned here with no success. I have put ground strapping on both sides of the hood, trunk lid, engine to firewall, several places from exhaust to frame. Currently has a Motorola M1225 VHF, has had two different Vertex and one Kenwood Radio installed for testing with the same results. I am suffering the same frustration, I have also tried shielding the coil packs with foil and grounding them. Nothing seems to attenuate this noise at all. It makes communication all but worthless on this vehicle. This vehicle does have factory Champion Resistive Plugs and no ignition wires. It is not frequency specific and interferes with portable radios in the vicinity also. We connected the radio to a bench switching supply at one point to further rule out noise entering via wiring and the noise was still present. Any help or updates would be greatly appreciated!

Thanks
Dave

KE9GK · Post by **KE9GK** » Wed Dec 12, 2007 9:54 pm

Dave,

Methinks we have a MOPAR issue on our hands here that nothing in the world is going to change. It is not any of your radios, nor is it electrical noise...this is good ol fassioned RFI. Our State Patrol has just a handful of these with the HEMI and they all suffer the same fate....on Ericsson Orion mobiles no less.....somehow I dont think the radio shop was intelligent enough to start the vehs after the install to even realize there was a problem. I have done all but take a sledge hammer to the car so I can collect the insurance for a brand new P71 Crown Vic (which I really dont miss all that much - waaayyy to slow compared to this rocket) I think our next step is to take it to Dodge directly and have them work on the problem. You cant mean to tell me everyone that is buying this car is putting it in service on a trunking 800 system where the RFI has no effect.....there is still a lot of public safety out there still on VHF...we just need to find them and band together against the mighty MOPAR empire of RFI....they finally pulled their heads out of their.....well you know....with the platform, now they just need to make it RF friendly! I have searched and searched the internet for similar concerns...but apparently not enough people who are a radio geek have one of these to annoy them enough into annoying Dodge about the problem. (annoy is a common theme here - get it) I am soooo open to anyones input at this time...I did go to the Dodge dealer with this concern but they blew me off and just gave me funny looks b/c the car is running fine...and RFI problems didnt really concern them - in fact they blamed the installer for not knowing anything and doing it incorrectly - YEAH RIGHT!!!!

--- FRUSTRATED BEYOND BELIEF!!!

abbylind · Post by **abbylind** » Thu Dec 13, 2007 9:24 am

Last Diplomat (Im dating myself) that I took to the dealership with an RFI problem I took a spectrum analyzer with me. I showed them the interference with the engine running and then how it goes away with the engine off. The light bulbs came on and the found a tech bulletin to fix the problem

Fowler

W2MB · Post by **W2MB** » Sun Sep 14, 2008 9:09 pm

Has anyone come up with a solution for this issue. I've got a 2008 Charger with a 5.7L Hemi and experience such noise on VHF signals of marginal strength. Clearly I am dealing with radiated noise and it appears to originate at the coil packs/sparkplugs.

007 · Post by **007** » Mon Sep 22, 2008 10:28 am

W2MB wrote:Has anyone come up with a solution for this issue. I've got a 2008 Charger with a 5.7L Hemi and experience such noise on VHF signals of marginal strength. Clearly I am dealing with radiated noise and it appears to originate at the coil packs/sparkplugs.

Start with replacing the coil-to-plug wires, as mentioned by abbylind...follow his directions and it should go away.

W2MB · Post by **W2MB** » Wed Sep 24, 2008 8:17 pm

007 wrote: Start with replacing the coil-to-plug wires, as mentioned by abbylind...follow his directions and it should go away.

What coil to plug wires? These vehicles use coil packs that mount directly to the plug. There are NO coil to plug wires, right?

twowaytekk · Post by **twowaytekk** » Wed Oct 08, 2008 2:35 am

We have several 07 chargers with the hemis, all police package models. We have VHF MCS2000 remote mounts, with the drawers mounted in the trunk. Some are using 1/4 wave while others are using 5/8 wave mounted to the trunk lid. We have not had any of the RFI issues as mentioned here. Perhaps it was a revison to the vehicle while in production.

Mark

007 · Post by **007** » Thu Oct 09, 2008 5:42 pm

W2MB wrote:
007 wrote: Start with replacing the coil-to-plug wires, as mentioned by abbylind...follow his directions and it should go away.
What coil to plug wires? These vehicles use coil packs that mount directly to the plug. There are NO coil to plug wires, right?

I am under the impression that there is a short wire under the coil onto the plug...never saw one up close - yet. Although re-reading Abby's post, it's not saying anything specific to the Hemi. Also, there are two plugs per cylinder so that's not helping anything.

007 · Post by **007** » Tue Oct 14, 2008 8:42 pm

Bump: Found this on Allpar.com...

Michael E. Gemmel wrote: “Each cylinder has an ignition coil pack over one spark plug, and a regular plug wire connected to the other spark plug. Further, the coil pack also has a plug wire attached to it that extends to the opposite cylinder bank. It appears that each cylinder shares a coil pack with another cylinder. Each of the two plugs on a given cylinder is fired by a separate coil. One plug has a coil directly attached, and the other is fired via an ignition wire connected to a coil located on another cylinder on the opposite bank. The benefits would be one-half the number of coils (8 vs. 16) compared to each plug having its own coil, and of course less weight.”

So there are plug wires and 16 plugs on a semi-Hemi* 5.7L V8...happy hunting!

* The current "Hemi" isn't quite the Hemi of old, but it's close.

W2MB · Post by **W2MB** » Sun Nov 09, 2008 8:41 pm

007 wrote:Bump: Found this on Allpar.com...

Michael E. Gemmel wrote: “Each cylinder has an ignition coil pack over one spark plug, and a regular plug wire connected to the other spark plug. Further, the coil pack also has a plug wire attached to it that extends to the opposite cylinder bank. It appears that each cylinder shares a coil pack with another cylinder. Each of the two plugs on a given cylinder is fired by a separate coil. One plug has a coil directly attached, and the other is fired via an ignition wire connected to a coil located on another cylinder on the opposite bank. The benefits would be one-half the number of coils (8 vs. 16) compared to each plug having its own coil, and of course less weight.”
So there are plug wires and 16 plugs on a semi-Hemi* 5.7L V8...happy hunting!

* The current "Hemi" isn't quite the Hemi of old, but it's close.

It runs liked a raped ape... and not too bad of an old fashioned sparkgap transmitter either. I've also found that using an HT inside of the car can play havoc with the digital circuitry behind the instrument cluster, seems that it can confuse the hell out of the automatic headlight system. Since it only has 3K miles on it, I'm not inclined to fart around with the ignition wiring, heck, I don't think that I could even find it... the simplest solution might be using 220 or 440 for yacking...

GroundRat · Post by **GroundRat** » Thu Jan 22, 2009 8:30 am

007 wrote:Bump: Found this on Allpar.com...

Michael E. Gemmel wrote: “Each cylinder has an ignition coil pack over one spark plug, and a regular plug wire connected to the other spark plug. Further, the coil pack also has a plug wire attached to it that extends to the opposite cylinder bank. It appears that each cylinder shares a coil pack with another cylinder. Each of the two plugs on a given cylinder is fired by a separate coil. One plug has a coil directly attached, and the other is fired via an ignition wire connected to a coil located on another cylinder on the opposite bank. The benefits would be one-half the number of coils (8 vs. 16) compared to each plug having its own coil, and of course less weight.”
So there are plug wires and 16 plugs on a semi-Hemi* 5.7L V8...happy hunting!

* The current "Hemi" isn't quite the Hemi of old, but it's close.

This is true for some of the older Hemi's.
My 2004 Ram had this set up - the coil pack was directly connected to one sparkplug and a sparkplug wire ran from that same coil, across the engine to a plug on the other head.

My 2008 Charger no longer has this set-up.
The Charger's have a single coil-pack with 2 plugs.
There are no cables running across the top of the engine anymore - makes for a cleaner engine bay.

Automobile manufacturers always cheap out on chassis grounding as far as I am concerned.
I'd recommend building a grounding halo in the engine bay.
I built a grounding halo in the engine bay of my 2004 Ram and my FM radio performed better (louder and clearer) AND my headlights were noticeably brighter.
I'd try building a halo ground in the Charger engine bay and make sure it is tapped into the ground coming off the battery so everything has the same potential.

Post by **radioinst** » Thu Jan 29, 2009 2:50 pm

Did you try to unplug one coil pack at a time to see if the noise decreases or goes away?

GroundRat · Post by **GroundRat** » Mon May 11, 2009 11:11 am

Any updates on this issue?

007 · Post by **007** » Mon Jul 13, 2009 5:48 pm

None from me any way. The vehicle in question was sold within a year of it's purchase and is long gone. Any of the Chargers I deal with at work now are V6's that don't have this issue.

tbski · Post by **tbski** » Mon Mar 29, 2010 6:50 pm

Anyone have anything further on this? Maybe knowledge of a TSB from Dodge?
I recently put in service a 2010 Ram with a Hemi with all the same described problems above. Been looking everywhere to get rid of the noise. Have a VHF Orion remote mount in the truck. Is clearly interference picked up from the air. Any updates would be appreciated.