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1-10 of 16 messages
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HF RFI on 2006 Crown Vic
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by N4BFD on November 5, 2009
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I purchased a used 2006 P71 Crown Vic recently, and have finally gotten around to using the HF side of my FT-857 in it.
Currently just using ham sticks on a fender mount, and I get interference that I've not really dealt with before. Basically, when accelerating I get a bit of noise which increases to the point that the receiver completely blanks out and the Smeter drops off the scale. The nature of it had me thinking at first that I had a intermitant connection to the antenna, but checking SWR while driving everything seems to be fine and the problem only occurs when accelerating. So far I've found this problem on 20-80meters.
I plan on bonding the body, doors, exhaust and engine to the frame this weekend, and wrapping the leads to the Cops and injectors with aluminum/copper tap, as well as the COPS.
I've had a F-150 made in the same year with the same engine, and had a bit of noise, but was able to knock it out doing the above.
Anyone else had a Crown Vic of recent vintage with this problem, and if so what did you do to solve it? I'd like to go with a 3" Hi-Q screwdriver, but want to make sure I can get rid of this problem before doing so.
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RE: HF RFI on 2006 Crown Vic
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by WA8FOZ on November 5, 2009
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Fuel pumps on all Ford products are notoriously noisy. There should be a service bulletin and a filter kit available from Ford. You may have to drop the tank to install it. I'm not sure whether this source would be totally responsible for the noise you describe, but it is a likely contributor.
Let's see what Alan says.
73,
Bill
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RE: HF RFI on 2006 Crown Vic
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by K0BG on November 6, 2009
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There is a filter kit as noted previously, but it should have already been installed at the factory. You can certainly ask the dealer to run the VIN and they can tell you for sure. If it isn't installed, be warned, it is NOT inexpensive. Part of the problem is, the kit is no longer available as a separate item, so they replace the whole pump. The last time I checked, it was over $450 just for the pump. They have to R&R the tank too.
Make sure what you're hearing is the fuel pump. I have a recording on my web site under Noise ID. If it is the pump, a cheaper method is to bead the power leads to the pump, and shorten up the ground lead. On some models, the lead is several feet long.
Remember too, the better the installation is, the better the S+N/N ratio, and the apparent "loudness" will decrease some. In any case, with proper bonding you should be able to get the noise level below S2. Start with the exhaust system, and hood.
If you operate the upper HF bands, you're better off with a screwdriver andtenna. The best one of those is the Scorpion, with the big Tarheel 400A close on its heels.
The problem with the other antenna is the large metal end caps, and the metal plunger. As the plunger moves toward the top end, it sandwiches the remaining, un-shorted coil between these two metal masses, and the Q can actually drop to zero. Wherein the coil starts looking like a rather lossy capacitor instead of an inductor.
Alan, KØBG
www.k0bg.com
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RE: HF RFI on 2006 Crown Vic
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by WB5JEO on November 6, 2009
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Do come back and report on the outcome. In the next couple of weeks, I'm putting HF into an 06 Crown Vic using small antennas. In my case, the short antenna is a result of both a daily trip through seven floors of a parking garage and the fact that a big antenna is a bit too eye-catching for what I use the car for.
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RE: HF RFI on 2006 Crown Vic
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by N4BFD on November 7, 2009
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Thanks for the response back guys. I plan on doing some bonding today. I ordered some braid, but it didn't make it yesterday, however I have about 20 or so straps I've already made up that I am sure I can use.
As I stated in my first post I have not done any bonding at all yet, so maybe this will take care of the problem without going into extremes.
The funny thing about the RFI/Noise I am getting is that I really can't hear it, it does seem to be throttle dependent though, so I am thinking it is the cops or fuel injectors. It totally blanks out the receiver. Such as on 80meters with the preamp turned off I may have about a S7 noise level with the car off, turn the car on with the engine at idle there really is no problem. Start going down the road the noise builds up a bit then it blanks out the receive completely, as if someone just flips a switch off. SMeter drops to zero when this happens. Very strong signals are pretty much wiped out.
The fuel pump itself runs at a constant speed if I am not mistaken? I don't want to totally rule it out, and if the bonding I do today, and maybe shielding the wire harnesses going to the injectors and cops don't work, I'll go down that road if need be. Access to the top of the fuel tank on a Crown Vic is a pain, it stands up vertically behind the axle and between the trunk.
I notice noise in this car all the way up to UHF. It was a former NC highway patrol car, I find it hard to believe that ford did not put a bit more effort into shielding these cars.
Thanks on the tips about the antennas Allan, I am keen on the Hi-Q 3" model currently. With the shape the bands are in now, I don't plan to operate on anything above 20meters anyway.
I'll report back tonight with the progress I made and hopefully some noticeable results of some sort.
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RE: HF RFI on 2006 Crown Vic
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by N4BFD on November 7, 2009
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I forgot to ask, WB5JEO what sort of antenna/s are you planning on using on HF that are short?
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RE: HF RFI on 2006 Crown Vic
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by N4BFD on November 7, 2009
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Bonded the doors, hood, trunk, exhaust and body to the frame in two places, ran out of straps.
Absolutely no change in the noise problem at all. Seems to be ignition noise, the noise blanker will work for a second or two, then bam, it spikes and the receive is completely wiped out almost as if a attenuator has been switched online.
I don't think it is fuel pump noise, I hear nothing when I switch the ignition on and the pump stirs, before the car starts.
I not did have time to wrap the wiring harness to the cops or ignition yet. It does not look too bad, the worst part is though that it wraps around the back side of the engine. It's just one harness that feeds them all it looks like.
I think I am just going to label then unplug everything on it, 20 plus connectors it seems, pull it, wrap it, then put it back. If that doesn't work I'll pull the cops and plate them with copper tape as well.
It would be cool if I could find some metal split wire loom. I've looked on the net and the only thing I find are some "metalized" plastic ones that have some sort of coating to give them a metal look.
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RE: HF RFI on 2006 Crown Vic
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by WB5JEO on November 8, 2009
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I'm putting on a 20 meter Shark mini, which is about the only sort that will mount in a conventional way on the trunk lid and clear the roof beams through seven floors of parking state parking garage. I've got some full size and all on quick disconnects for when I'm on the road. Hardly the most efficient antennas, but it suits the situation. Six more years, and I retire and ditch the Crown Vic and can go crazy.
Someone speculated that the Crown Vic police package ("Police Interceptor") might have extra RFI measures. The police package and taxi package are very similar, mostly about oversize radiator, transmission cooler, heavy suspension, and heavy alternator and maybe now a special gas tank shield because we had some problems with tanks breaching in rear-end collisions because of the habitual heavy loading of the trunks with equipment, and they have bonding straps. Radios are all VHF and UHF FM and rarely have any noise problems, no matter what type of vehicle they're in, with or without RFI measures.
It's interesting that it seems to kick in after you start off. I know in mine, which is a consumer model, the doors automatically lock down at about five miles per hours. I wonder if something's not releasing. Might be worth asking a Ford shop mechanic what all happens as you start moving. There could be a whole bunch of things changing modes at that point, including something as simple as a digital speedometer starting to display. If it's that strong, maybe a portable radio or a bare wire probe on the end of a coax would help narrow it down, which presents a tricky problem in probing for it in motion. Probably best done on a lift at the shop. In older models, the fuel pump was a regular serious offender that was cured with ferrite beads.
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RE: HF RFI on 2006 Crown Vic
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by K0BG on November 8, 2009
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The differences between the regular Crown Vic and the Interceptor mainly are mechanical and trim alterations.
Depending on the ordering body, it may or may not have: wiring conduit, zippered headliner, flash-light wiring (for strobes), and switched power leads. The alternator is a little larger (120 versus 105), and the battery is a size 34 as apposed to a 24. Other than that, they're the same animal, including the engine. There is an option for the 5.4 L engine, but it is very rare. Ford says only 1 in 100 or so have the bigger engine, and most of those are bought back and destroyed.
Alan, KØBG
www.k0bg.com
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RE: HF RFI on 2006 Crown Vic
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by K5LXP on November 9, 2009
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I'm running HF in a grand marquis, with the 4.6L engine. In sniffing around it seems (at least in mine) the injectors are the worst offender. 2nd is the digital instrument cluster. I too detect the noise changes with throttle and the injectors would be the first thing I would look at. I took few measures with my RFI mitigation since the worst I saw was S5, and the noise blanker takes it down to an S-unit or so, which was "good enough" for what I wanted. Would be curious to know though if shielding the FI or COP harness has any effect. It wouldn't be a trivial job from what I remember how mine is laid out. The harness goes behind the engine between the firewall and transmission bell housing, and it's a real PITA to get at it.
Mark K5LXP
Albuquerque, NM
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