I have a 2003 6.0 F350 with 78,000 miles. Recently, the truck has been running extremely rough and smoking heavily after a cold start. The weather here has been getting colder, and yesterday it was 30 deg. in the morning. It took 3 attempts to start, and the truck chugged and knocked and banged for about 2 minutes, accompanied by clouds of heavy, gray smoke. Fast idle didn't kick in until after 5 minutes.

I researched on this forum, and discovered that among the many possible causes, weak or dying batteries could be the culprit. My batteries are the originals, which are over 7 years old. I also learned that weak batteries can destroy the FICM, so I decided to replace them.

I purchased two batteries from Walmart (Johnson Controls, 850CCA, 3 yr. replacement warranty), and installed them. Today when I started the truck, it was again 30 deg., and this time it started just like in the old days! Immediate light-off, minimal smoke for about 10 seconds, then fast idle after 20 seconds.

Just to be sure, I checked alternator voltage with engine running, and had 14.1 volts. So it looks like the batteries were trying to tell me something. I'm glad it wasn't sticky injectors or other expensive issues.

 

Were those the original batteries?????

 

As far as I know, they were the originals. The were Motorcraft, and I purchased the truck when it was three years old. I have the previous owner's service records, and there is no mention of a battery replacement in the first three years. They were good batteries, I guess!