So I completed my 36-hour trip home, and man did I burn tons of fuel! I drive this route twice a year, once in the summer and once for the winter holidays. Empty the truck normally pulls around 20 mpg summertime and 18-19 on the winter fuel, all interstate. Last summer there was a big and heavy camper loaded in the bed, I got 14-15 mpg, which is not unreasonable when you're pushing 80 sq. ft brick wall at 55 mph. This time around, I got 10-11 mpg, basically I'd fill up 18 gallons ($60) in the front tank then drive like 180-190 miles on them and have to refuel again. I have no problems with my regular 2 mpg drop due to winter fuel, but 4 mpg drop when I'm already at 14 is hard to swallow financially. Changes made to truck just prior to leaving:
1) injection pump retarded slightly, for the last two years it was so advances it was maxed out in the adjusting slots and the high-idle solenoid was pretty much hard against the upper radiator hose and she was eating glowplugs on regular basis (2-3 every year), from that position I retarded it no more than a quarter's thickness. She starts quite a bit easier now, and maybe the plugs will last.
2) removed the wind-deflector plate from under my bumper, as it was all bent up from me hitting curbs with it.
Several things I noticed while driving - my temperature gauge stayed quite low, much lower than normally - I'm used to seeing at the O and R of "NORMAL", with it climbing to the "M" when I'm heavy on the throttle pulling uphill, now she was just at the beginning of the "N" letter while cruising at steady speed and barely getting into the "O" with my foot on the floor. The haze that was associated with part-throttle under load also seems to have disappeared, or at least quite severely diminished.
So I'm thinking by retarding the pump the engine actually burns the fuel more complete now (as evidenced by the lack of excessive smoke), while ditching the deflector plate allowed more air through the radiator thus keeping everything much cooler. Lower engine temps do make for worse fuel economy, right?
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yes.you want a good 200-210 degrees idi so she burns the fuel good i think.
if you notice the PSD forum,they run 203* t-stats because they discovered the higher temps helped the diesel to run more efficiently.
timing by ear is so hard though.you may have retarded too much.
you may have been at 10* BTDC since it was eating gp's -or close to it.but you could be at 5 or 6* BTDC now which could hurt your economy.
how did the exhaust sound? a lot louder than normal? iv read the exhaust can get real loud when the timing is retarded to far.so hopefully this helps.
What was the recommended timing for these things 8-9* BTDC? I have the feeling it was way too advanced before I mess with it, cause the IP was turned so far to the right that you physically couldn't turn it any more. If you remember I've mentioned several times that when I engaged my cold-advance solenoid on a hot engine it would try to go runaway on me, I don't recall anyone else (even people with properly advanced IPs) reporting anything like that. So I'm thinking it's actually better now, but still a bit on the advanced side, cause she sounds like a powerstroke at cold idle, but also still has a distinct rattle at warm idle when the advance solenoid is off.
And I know what retarded timing sounds and smells like, this is the reason why I advanced the pump two years back, I don't have any of that now, even after retarding it slightly from its maxed out position.
On the temperature thing, I bet I'm running colder than optimal now, which as you said could result in a drop in fuel economy. The valance itself is not anything factory, it's a 6" tall 3 ft wide aluminum piece that bolts to the bottom of my bumper to reduce air flow under the truck and deflect it up in front of the grille. So removing it actually makes sens with respect to increased cooling, cause it allows more air to go under the bumper and be sucked in the radiator... If I put it back on then I'll lose the extra cooling, which I would rather restrict manually with cardboard in front of the rad.
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I run a 180* t-stat on my 6.9 motorhome. My real gauges shows infact 180* cruising on flat ground, @ 100km/h on cruise control (62mph). It keeps the temps* around 180 no problem, but in the hills, gets up to 200* and fan locks in and stays around that depending how hard shes working.
I still get ~12mpg out of that 3 speed rolling cottage!
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1990 Ford F250 4x4, ZF5, L/S 4.10, N/A 7.3L Diesel, 568,796km/377,497 miles, still on the original clutch!
1989 Ford F150 300-6, C6, 2.73, 116,000km/71,000 miles.
1987 Ford E350 26ft. Motorhome, N/A 6.9L Diesel, C6, 3.54, 250,000km/157,000 miles.
1985 Ford E350 Ext. Cargo Van, N/A 6.9L Diesel, C6, 4.11, 148,000km/92k miles
How heavy is your rolling cottage by the way? Mine is probably around 8000-9000 lbs, and we have the same front air resistance, so me having OD should help me get better fuel economy than you. Then again, is your 12 mpg running on summer or winter fuel?
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Feel no sorrow, feel no pain, feel no hurt, there's nothing gained...
How heavy is your rolling cottage by the way? Mine is probably around 8000-9000 lbs, and we have the same front air resistance, so me having OD should help me get better fuel economy than you. Then again, is your 12 mpg running on summer or winter fuel?
It's stored for winter, so no worrys about winter fuel. lol
12mpg on summer fuel, although I do wait till winter fuel comes out before storing it, and when I do take it out of storage to go on our first trip, the fuel gauge goes down really quick, so it's most likelly under 10mpg on winter fuel.
11,000 pounds with basic stuff inside, weight varies depending how long we leave for. Longer we are gone, heavier it gets.
C6 with 3.54 and 6 215/85R16 tires inflated @ 70psi.
Cruise control @ 100km/h (62mph) engine sounds like it's turning around 2400-2600RPM.
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1990 Ford F250 4x4, ZF5, L/S 4.10, N/A 7.3L Diesel, 568,796km/377,497 miles, still on the original clutch!
1989 Ford F150 300-6, C6, 2.73, 116,000km/71,000 miles.
1987 Ford E350 26ft. Motorhome, N/A 6.9L Diesel, C6, 3.54, 250,000km/157,000 miles.
1985 Ford E350 Ext. Cargo Van, N/A 6.9L Diesel, C6, 4.11, 148,000km/92k miles
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