2004 5.4L vs, 2005 5.4L
08-03-2008, 08:07 PM
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lwjustice
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2004 5.4L vs, 2005 5.4L
I have a 2004 Lariat SC with the 5.4 and my son has a 2005 XLT SC with the 5.4, both auto trans. The 2004 get substantially better fuel mileage (21 hwy) vs the 2005 @ (16 hwy) same driver same route. What could be the diff? Also, 2005 has what appears to be a backfire situation when accelerate to 3500 rpm no lode and let off, 2004 has no isse with this?
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Confused?
08-03-2008, 09:45 PM
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Amatuer Lumberjack
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The '05 is a heavier truck than the '04. Ford did a lot to make the newer F-150s stronger trucks and they added a lot of insulation to the dash, which adds weight and hurts fuel economy.
08-04-2008, 10:59 AM
#4
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Your 05 with the backfire on decelleration is interesting. I'm assuming no codes are being thrown, sure sounds like the 05 is running rich. Not an expert on the computors and what could be the cause or remedy. Perhaps others will offer up info.
08-04-2008, 05:11 PM
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lwjustice
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08-04-2008, 05:17 PM
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lwjustice
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The '04 is the new body which supposedly has those enhancements (new stiffer frame, sound dampening etc.) Sise by side they are identical except for trim. The '04 has more of it (step rails, leather, power slider) and the '04 performes better. Go figure!
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08-04-2008, 05:22 PM
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lwjustice
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I've driven both vehicles the same route to and from work so that we compare using same driver profile. so the foot's not the problem.
08-04-2008, 08:25 PM
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Well, the 3.73s would give you better mileage in town (less power to pull from a dead stop), but the 3.55s would give you better mileage on the highway (Steady State...motor would be turning less rpms).
I think Bill is right, the backfire on decel just may be a VERY big clue. Way too much fuel being dumped in. Sounds to me like something is amiss with either the injectors, or the fuel map the ECU has selected.
The cheapest and first thing to try would be a nice fuel injector cleaner, in case one of the injectors is "pissin" rather then spraying. Second option is to get a datalogger on it, if you know someone in your area with an OBDII logger. Take a look at the o2 sensor readings and long term fuel trim adjustments. If the o2 sensor(s) is(are) going bad or fouled, the ecu thinks it's running lean and adds more fuel, but in reality is throwing in fuel when it's not needed....resulting in cruddy mileage and decel popping.
I think Bill is right, the backfire on decel just may be a VERY big clue. Way too much fuel being dumped in. Sounds to me like something is amiss with either the injectors, or the fuel map the ECU has selected.
The cheapest and first thing to try would be a nice fuel injector cleaner, in case one of the injectors is "pissin" rather then spraying. Second option is to get a datalogger on it, if you know someone in your area with an OBDII logger. Take a look at the o2 sensor readings and long term fuel trim adjustments. If the o2 sensor(s) is(are) going bad or fouled, the ecu thinks it's running lean and adds more fuel, but in reality is throwing in fuel when it's not needed....resulting in cruddy mileage and decel popping.
08-04-2008, 11:31 PM
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lwjustice
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I did put a can of Berryman's b-12 in on Sunday with about a 1/4 tank of fuel (ratio was the suggestion of local NAPA guy). I'll see what I can do about getting my hands on a logger.
Thanks for the suggestions.
Thanks for the suggestions.
Well, the 3.73s would give you better mileage in town (less power to pull from a dead stop), but the 3.55s would give you better mileage on the highway (Steady State...motor would be turning less rpms).
I think Bill is right, the backfire on decel just may be a VERY big clue. Way too much fuel being dumped in. Sounds to me like something is amiss with either the injectors, or the fuel map the ECU has selected.
The cheapest and first thing to try would be a nice fuel injector cleaner, in case one of the injectors is "pissin" rather then spraying. Second option is to get a datalogger on it, if you know someone in your area with an OBDII logger. Take a look at the o2 sensor readings and long term fuel trim adjustments. If the o2 sensor(s) is(are) going bad or fouled, the ecu thinks it's running lean and adds more fuel, but in reality is throwing in fuel when it's not needed....resulting in cruddy mileage and decel popping.
I think Bill is right, the backfire on decel just may be a VERY big clue. Way too much fuel being dumped in. Sounds to me like something is amiss with either the injectors, or the fuel map the ECU has selected.
The cheapest and first thing to try would be a nice fuel injector cleaner, in case one of the injectors is "pissin" rather then spraying. Second option is to get a datalogger on it, if you know someone in your area with an OBDII logger. Take a look at the o2 sensor readings and long term fuel trim adjustments. If the o2 sensor(s) is(are) going bad or fouled, the ecu thinks it's running lean and adds more fuel, but in reality is throwing in fuel when it's not needed....resulting in cruddy mileage and decel popping.