How does a ficm get weak?? - Ford Powerstroke Diesel Forum
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post #1 of 5 Old 12-24-2009, 08:16 AM Thread Starter Rookie
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How does a ficm get weak??

I've been digging through ficm threads trying to understand my rig a little better, it stars worse every year, first winter it started like a gasser, next just ok, then we had to tow it out of the barn with a 1969 oliver diesel because my '03 wouldn't start in 0* weather, dealer has been reflashing it year after year with the last time replacing 3 injectors, every time i get it back it's much better, but never like it's first winter and gets worse again every year.
So I was basically wondering if a ficm can really get weak? or it just keeps getting reprogramed covering up bad injectors? Seems like the ficm being an electrical thing would either work or not. hard for me to think of a computer going retarded.
It runs so good when it runs I'm just sick of it going retarded on me, the thing should've been a short bus.

95,000 mi, '03 march build, 5w40 and fuel treatment for the winters, oil changes every 3k fuel filters every 6k.
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post #2 of 5 Old 12-24-2009, 08:20 AM
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Weak batteries will slowly kill the FICM. Check your batteries!

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post #3 of 5 Old 12-24-2009, 02:15 PM Thread Starter Rookie
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thats the thing that gets me though, It's just hard for me to subscribe to "it wears out" or "gets weak" I just picture stuff that actually moves, like relays or bearings, wearing out/ going bad. Or a compasitor/ resistor going out but a circut board just gets weak??
I'm not saying it dosen't happen because it obviously IS an issue, I'm just trying to understand this thing and appreciate all the help you'll tolorate with me. Thanks.

Batteries new last year, never seems to have been a shortage of voltage. I even swaped them out because I needed a couple for mudders/tractors and put my old ones in them and gave the truck the new.
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post #4 of 5 Old 12-24-2009, 03:23 PM
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Basically heat will take its toll on the micro electronics within the FICM. there are two 20a coils on the injectors that drive the spool valve, there are converters that take the nominal 12v and step it up to 48v in theory, lol. as these injector coils age, resistance increases which will increase current draw, there are also connection issues that can effect as well as low input/supply voltage B+ and low alternator output. low voltage and low alt output will kill an FICM, but! so will high resistance injector coils which incidentally will cause cold start and drivability concernes and... injector codes.

We now scope current draw on the injectors, cold start and operating temp any time we have to replace an FICM, it is a PITA but can identify failing or soon to fail injectors. so while electronics might not "wear out", they can, well, wear out, lol

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post #5 of 5 Old 12-25-2009, 07:28 AM
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Your FICM makes like 48 volts out of like 13 volts. So in doing this the ficm will get hot, thus could cause the solder joints to crack. When it is cold the joints will separate more and more, this causing less voltage to your injectors. When it warms up outside some the joints close and it works somewhat fine. There are ways to check your voltage and possibly correct the problem by re flowing the joints. Here is a link that could help you better understand your ficm.

FICM testing procedure - Ford Truck Enthusiasts Forums
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