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

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

ad: L-HROutlet
ad: l-rl
ad: Left-2
ad: Left-3
ad: L-MFJ
ad: HRDLLC-2
ad: L-Geochron
ad: MessiPaoloni-1
ad: abrind-2
  1. N4MU

    N4MU Ham Member QRZ Page

    Mine is a 6.7L turbo. I looked into the Bulletproof items but am not sure I have a problem with the module. Not tested but my gut says it's doing the job it was designed for. I am leaning toward ferrite (big guys) on the PCM cable bundles to see if the pulse noise (relay collapse spikes) will be minimized. What say you folks? Also, I came across an article from a ham-author who tried ferrites and then grounded the negative terminal of one of the batteries and the injector noise disappeared. Not so with my situation. Anyway, wouldn't that defeat the purpose of the negative lead sensor thingie? Ahhh, a continuing saga...
  2. K0BG

    K0BG Ham Member QRZ Page

    You want to be very careful how much ferrite, and where, you install them. What you don't want to do, is integrated the digital signals (round them off in their edges). Ford specifically is one of the best at properly shielding and filtering their digital hardware. That is not to say you can't improve on them, but if things start acting up, and cause the MIL to light up, you went too far!
  3. K5RCD

    K5RCD XML Subscriber QRZ Page

    You may or may not have an issue with the FICM, but you can't tell by gut feelings. If it is consistently putting out less than 45 volts, it can run and start OK, but the low voltage can damage your injectors, which are quite expensive to replace, and there are 8 of them. It's easy enough for a dealer or knowledgeable mechanic to measure the FICM output and put the matter to rest. If anything is out of the ordinary that might suggest a possible FICM failure, it's wise to find out before it causes further damage. It's kinda like the 7 warning signs of cancer.

    As Alan states, ferrites on the fuel system electronics are not a good idea. Pulse width, timing, and voltage are critical to injector operation. Note that the fuel injectors are not opened electrically, but by engine oil under high pressure. The timing of the injector operation and the amount of time they stay open is controlled electrically by the FICM. They are internally lubricated by fuel. If any of that gets messed up, the injectors can suffer fatal damage. Think of the FICM as a series of capacitors and imagine the potential for RFI of any leakage.

    I'm not saying the injectors are the RFI culprit, but the Ford / International diesels have never had a reputation for creating RFI. Having no ignition system makes them less vulnerable overall.
  4. N4MU

    N4MU Ham Member QRZ Page

    Alan & RCD: Thank you both. I had sent a reply to Alan but don't know where it went. Maybe it will show up next month...
    I have taken both of your cautions seriously. I sure wish I could find a decent diesel mechanic who also is familiar with RFI. I would mention this at my next local club meeting but I am afraid of all the "free advice" I would get. In the meantime I guess I will just grin and bear it.
    If it's NOT injectors and/or the FICM, which by the way, in my vehicle is really the PCM...all in one box as far as I can tell, what might it be? It sure sounds like sharp staccato pulse noise that varies with what would be injector activity...faster>quicker pulses...slower>more spaced out pulses...take foot off accelerator>>>after about a second NO NOISE at all...for about 1 to 2 seconds, then it starts again. Injectors??? Or what?
  5. K0BG

    K0BG Ham Member QRZ Page

    The correct email address for all, is This bypasses my filters!

Share This Page