I own a 2006 F350 CrewCab Harley Davidson 4x4 with 117k miles bought new. Before it turned 100k warranty replaced the EGR valve twice. After the warranty expired I added a 4 inch exhaust, airraid cold airfilter and the Hypertech chip using stage 3. Fuel mileage increased 4.5 miles per gallon. Two days ago my interior heater would start blowing hot air and within 3 minutes would blow cold, would turn off heater and turn back on and would be hot for 5 minutes then go cold. Also noticed it was blowing black smoke on acceleration more than usual, but when I would decelerate it would sometimes blow a bluish smoke. This all started when the heat was going out (probably coincidence). Any conclusions would be appreciated.

Rocky

P.S. This is the 6.0 Powerstroke

 

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