2006 F350, 6.0 PSD, CC, SRW 4x4:
Back in December I had my FICM replaced by the dealer under warranty. Old one was getting low voltage on start up. Prior to the replacement, I was getting 13-14mpg in the city, and since the replacement I am now only getting 10-11mpg. Nothing has changed as far as how/where I drive. I first noticed this with my scangage II, I thought I was getting bad readings, so I filled up, tracked my mileage and did the math and came up with the same thing my SGII was telling me.

In addition to having the FICM replaced, I changed the oils in the tranny, front/rear differentials, transfer case, power steering, brake system, and changed over to Rotella T-6 from 15w-40. I use all OEM filters and use Diesel Kleen on just about every fillup. But I can't imagine any of this would affect the fuel mileage. Tire pressure is good too.

I am assuming that when Ford replaced my FICM, that they flashed it with the latest and greatest. So my question is, would the FICM most likely the cause of the decreased fuel mileage, would having the FICM re-flashed maybe improve it? If not the FICM, what else could have caused an immediate reduction in fuel economy if all other variables haven't changed? I'm out of ideas......

Thanks.

 

Winter blend fuel? I have heard that decreases mileage. It seems to happen to mine in the winter. Maybe the two happened at the same time.

 

When you said 'brake system' do you mean just the fluid, or did you do new calipers, rotors, pads etc?

Could be you got a hungup caliper dragging you down?

 

I'd bet the reduction in mileage is due to the latest "greatest" flash. Some folks report no difference and some report a loss in power and mileage. Winter blend fuel could have some affect but it was out way before December.

 

That would be nice if that was the cause, at least I could look forward to my mileage improving (maybe).

 

I just did a flush on the system, no calipers or rotors. I thought about the possibility of a dragging brake, if that were the case, I figured I'd hear it, or feel the truck pulling. So I haven't explored that any further.

 

What do the flashes actually do, and can they be reprogrammed to be more fuel efficient without mucking things up?

 

Okay. Hope you get to the bottom of it. $4.15+ a gallon up here in New england.

 

I just filled up for $3.80/gal, but I'm sure it will go up by my next fill up.

 

I agree with npccpartsman you probably got the latest flash.That would explain the drop.

 

Just spoke to a friend who owns a Duramax... He had some work done a the stealership (fuel filter bowl replaced). His ride dropped from 19 hwy to 15 hwy, and now smokes at idle. He's been fighting the issue for awhile.. found a Diesel Tech (International, Cummins, Ford, etc) who told him the dealerships get updated computer flashcodes several times a year. He said the dealerships will not tell you this; " but they are required to flash your computer every-time you bring it in". And most of the time, the new flash codes produce poor fuel economy. He expressed his disgust at this practice. Said the old codes are just fine.

Anyway, my point is this; maybe the new flash codes for the ECU and FICM are horrible and causing your excessive fuel consumption. Just a thought..

Hell, sounds like someone's in bed with the oil companies. (sorry, different topic)..

 

If you think it's a new flash problem, talk to Power Hungry Performance. I believe they can send you a device and flash you back to an older version that might work better for you.

 

Looks like they have some cool stuff there. I'll have to do a little research see what I might could use. Thanks for the heads up.

 

I had a caliper hange up and the next thing I knew the wife was calling to tell me there is a fluid leak on the left rear wheel caliper eat through the pad and backing fell out and had it's way with the caliper pistons; shattered them . Wife puts more miles on the truck than I do. she said it did not make any noise, the other side 3/8 of pad left. I would personally like to thank FORD for decreasing my milage from 21 to 17 hwy they took away the original pre-injection on my 04.

 

As others have hinted, the newer flash is causing your lower fuel economy. You probably had the original, early '06 flash and now the latest which has more retarded timing for emissions and headgasket life. Contact PowerHungryPerformance, they can flash your FICM to a modified economy tune (or a higher power tune) for around $150 and you should get the mileage back with a little more pep.