Install Complete...Now tackle the noise...

Discussion in 'Mobile Radio Systems' started by N4MU, Sep 24, 2019.

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  1. N4MU

    N4MU Ham Member QRZ Page

    I've completed my F-350 diesel and FT-857D install. Not too shabby if I do say so myself. Radio is in a compartment under the rear seat. Now...I'm left with what Alan (K0BG) calls injector shuttle noise. I didn't even know I had one! It is as high as S8 and is definitely coming in via the antenna. I walked around the vehicle with my trusty Tecsun PL-880 and it's there. Curiously, in front of the vehicle it is least...but still obvious. If I wanted to pull a 10' trailer behind me and put the antenna on it I'd be all set. The noise "vanishes" at 10-15 feet out.
    Question: The noise is worst on 80, 40, 30, 20 and diminishes the higher in frequency I go. On ten meters it is barely perceptible. That being the case (VERY broadband ratchet type pulsing; varies with speed), why don't I hear it on the AM band with the vehicle radio??? What do they do that I haven't done? Otherwise, the vehicle produces negligible "other" noise from all the myriad of electronics on board.
  2. KA9JLM

    KA9JLM Ham Member QRZ Page

    Normally they use a bypass capacitor.
    N0TZU likes this.
  3. K0BG

    K0BG Ham Member QRZ Page

    Depending on the year, the injector system is mechanical (not used for many years); uses a shuttle system (sort of semi-electronic), or fully electronic using piezo injectors. I suspect the latter. The RFI is rhythmic like a standard ignition system, but with a different staccato. You cannot bypass the piezo injectors in any way, as doing so integrates the digital signals driving them, with predictable results. You could use additional ferrite beads, but Ford has done about all that needs to be done in that respect.
    K0UO and KA9JLM like this.
  4. N4MU

    N4MU Ham Member QRZ Page

    Thanks JLM, Hello (again) Alan.
    Yes, I agree, as I have in our past discussions. It would seem that I have a piezo type, and as you stated to mess with that would open a whole new can of noise. The vehicle is a 2011 F-350 diesel.
    Guess I'll just have to learn to live with it. Relatively strong signals can be heard well when at or over the noise level so I'm not out 100%...just have to use the RF gain, etc., and talk with stronger stations...okay by me.
    BTW, had the oil changed this morning (at local Ford dealer) and no one there had ever heard of an injector shuttle. They understood what I was explaining but just had never heard the device called that. So much for advancements in auto technology.
    Also, still wondering why it's not evident on the AM radio. It is definitely coming in via the antenna so just curious why I don't hear anything on the AM (factory) radio. If it is a bypass somewhere I want one! But, fact remains, definitely in via the antenna. Guess I'm "hosed"!
  5. K0BG

    K0BG Ham Member QRZ Page

    Let's see if I can make this sound a bit less confusing. Essentially, the "device" which initiates the injection of fuel, is controlled by the engine's computer, and not some specific amount based on RPM, load, etc. The mechanical part of the system, which controls which cylinder to spare fuel into, is called the "shuttle". Ford never called it that. I think the term originally came from Caterpillar, but I'm not sure of that.

    I think the surprising thing about piezo injectors, is the fuel rail pressure. Most hover around 100 bar (1,500 PSI), but a few are over 300 bar (4,500 PSI). At those pressure levels, the fuel is very close to self-igniting. How they keep that from happening must be a trade secret!
    K0UO likes this.
  6. KB0MNM

    KB0MNM Ham Member QRZ Page

    Based upon the RF noise report, you may want to see if N6NB still builds homebuilt antenna trailers. Getting the antenna off of the ground plane of the vehicle might solve the problem. For VHF and UHF, some of the 'luggage mount' antennas sold by Diamond had specific recommendations regarding wavelength. For HF, there would be no such elements. The vehicle radio is not as much a broadband receiver as your ham rig. Remember that the dial on AM broadcast is in KHZ., not in Mhz. A handheld A.M. radio would have a more broadband front end, so does that describe the Tecsun PL-880?
  7. K5RCD

    K5RCD XML Subscriber QRZ Page

    I think what Alan is calling an injector shuttle is what Ford calls a Fuel Injection Control Module (FICM). Had that system on my 2005 F350 6.0 L diesel and nary a hint of interference from it. BUT, if the FICM is even a little faulty, it can cause RFI, and of course problems keeping the truck running properly. The FICMs are notorious for having a weak solder joint inside, that starts to crack or separate over time due to vibration and temperature fluctuation cycles. That can cause the RFI problem. Usually the FICM voltage will begin to drop just before the unit finally fails. Have your FICM checked and replaced if necessary before it lets you down out in the middle of nowhere.

    Another thing to look for is to make certain the vehicle chassis ground is properly installed and maintained.
    AK5B and KB0MNM like this.
  8. N4MU

    N4MU Ham Member QRZ Page

    RCD...and all others: Thanks for the tid-bits! I will pursue the FICM thing...on the back burner though. I'm sure they would be a bit "spendy". VERY interesting experience however. Truck only has 73K on it and really don't want to start replacing things prematurely. I will keep that in mind however...and "quiz" the diesel "experts" next visit. Thanks to all...guess I'll do my mobile...stationary. Safer anyway...HI.
    PS. Is this FICM something that is external and easily replacable...i.e. plug and run? Or does it require getting into the innards and/or setup?
  9. K5RCD

    K5RCD XML Subscriber QRZ Page

    It only takes a few minutes to replace the FICM. If truck is still in an extended warranty I would consult Ford dealer to test voltage output, which tends to decrease or fluctuate as it nears failure. A diesel performance shop might be a better place to go. They have rebuilt FICMs and aftermarket 54 volt FICMs that are nearly bulletproof. A diesel performance shop has probably seen it all, and maybe more likely to troubleshoot it than a Ford dealer. You can do it yourself if you are tech savvy.

    Here is a link to an article that gives some explanation of the issue.
  10. NG1H

    NG1H XML Subscriber QRZ Page

    [QUOTE="K5RCD, post: 5208741, member: 261562[/QUOTE]

    If you have a 6.0L the FICM is probably way down the list of your problems.

    (Yes, I am joking. Sort of. The 6.0 can be made into a good engine with a moderate amount of money. Less money than a newer vehicle would cost. IIRC in the $8k range. But since the older 7.3L often brings a higher premium it actually isn't a bad choice for the informed buyer who isn't planning on reselling.)

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