BAD MPG's...
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BAD MPG's...
I have searched...but the results did not match what I am seeing...
heres the story.
Wife was getting pretty bad mpgs's and was smelling some gas on occasion.
then got a SES. Code was p0402 - changed the DPFE. Also seemed like smell was coming more on passenger side of engine, we had recently replaced all plugs and pulled the injector harness off...so we replaced o-rings on top and bottom on that side.
Light has stayed off, for several days of driving. Gas smell went away it seemed like. Filled up with fuel Monday, and as of last night had gone 73 miles on 1/4 tank of gas. If that were right...its only 4mpgs. I am asking her to fill it after work so we can see a little better what it is. (she says right now its between 3/4 and 1/2 with 113 miles...that would be more like 10mpg)
There are no codes right now. She said driving in town she noticed the fuel smell a little again. Garage does not smell like gas or anything though, so if its a fuel leak its not leaking if its not running (at least that is my guess).
The one drivability thing we have noticed is that there are times that it has a little hesitation, or lurching going on. For instance, cruise set at 60 and you start to go up a little hill...you feel for a few seconds several little "bumps" or something as it starts to accelerate. Power seems good though...
OTHER DETAILS...
99 f150 5.4l.
207k miles (we bought it 30 days ago with 205k)
driving is to work 30 miles each way. 60mph. country highway, only one stop sign until the last mile. Should be about perfect driving conditions other than winter fuel.
no lift, stock size tires, no chip etc.
recently replaced air filter,
replaced 4 coils so far (aftermarket)
replaced all plugs (Motorcraft)
replaced DPFE
replaced PVC and vacuum harness on the Passenger side.
replaced all O-rings on passenger bank of injectors
no SES light.
no codes or pending codes
small oil leak (rear seal I think)
true dual exhaust
maybe a little smoke from drivers side exhaust...very light.
Would like to get it to 15mpg on the highway at 60mph...
Had 13mpgs 3 weeks ago.
heres the story.
Wife was getting pretty bad mpgs's and was smelling some gas on occasion.
then got a SES. Code was p0402 - changed the DPFE. Also seemed like smell was coming more on passenger side of engine, we had recently replaced all plugs and pulled the injector harness off...so we replaced o-rings on top and bottom on that side.
Light has stayed off, for several days of driving. Gas smell went away it seemed like. Filled up with fuel Monday, and as of last night had gone 73 miles on 1/4 tank of gas. If that were right...its only 4mpgs. I am asking her to fill it after work so we can see a little better what it is. (she says right now its between 3/4 and 1/2 with 113 miles...that would be more like 10mpg)
There are no codes right now. She said driving in town she noticed the fuel smell a little again. Garage does not smell like gas or anything though, so if its a fuel leak its not leaking if its not running (at least that is my guess).
The one drivability thing we have noticed is that there are times that it has a little hesitation, or lurching going on. For instance, cruise set at 60 and you start to go up a little hill...you feel for a few seconds several little "bumps" or something as it starts to accelerate. Power seems good though...
OTHER DETAILS...
99 f150 5.4l.
207k miles (we bought it 30 days ago with 205k)
driving is to work 30 miles each way. 60mph. country highway, only one stop sign until the last mile. Should be about perfect driving conditions other than winter fuel.
no lift, stock size tires, no chip etc.
recently replaced air filter,
replaced 4 coils so far (aftermarket)
replaced all plugs (Motorcraft)
replaced DPFE
replaced PVC and vacuum harness on the Passenger side.
replaced all O-rings on passenger bank of injectors
no SES light.
no codes or pending codes
small oil leak (rear seal I think)
true dual exhaust
maybe a little smoke from drivers side exhaust...very light.
Would like to get it to 15mpg on the highway at 60mph...
Had 13mpgs 3 weeks ago.
thread jacker!
Joined: Apr 2010
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From: Baker, Fla
13s about normal unless you really baby it. i got 15 on my 5.4 earlier today, but i do baby it a lot. ill get about 100 miles on the forst 1/4 of a tank. if you havent changed the fuel filter and oil, and all that id do that and see if it improves.
Senior Member
Joined: Apr 2009
Posts: 3,683
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With the p0402 code it wouldn't be a bad idea to clean the throttle body and EGR ports. Also look into new front O2's with that many miles.
Since it's me I have to ask: what size exhaust system is on it and does it have a crossover?
Since it's me I have to ask: what size exhaust system is on it and does it have a crossover?
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Exhaust is an interesting deal. When we bought it someone had cut the exhaust and had two big cherry bombs on it and no tail pipe at all. Part of the purchase was having it fixed. Car lot had a muffler shop put in a Dual In dual Out muffler and tail pipes out the side behind tires (we occasionally haul horses) I forget the muffler name...its a flowmaster knock off...lol. There is no x pipe or anything...far as i could tell from the website for the muffler there was not even internal to the muffler.
I have been planning to to a good TB clean...but its been so cold...Will try that this weekend. Can change fuel filter then also.
I have been planning to to a good TB clean...but its been so cold...Will try that this weekend. Can change fuel filter then also.
Senior Member
Joined: Apr 2009
Posts: 3,683
Likes: 171
Exhaust is an interesting deal. When we bought it someone had cut the exhaust and had two big cherry bombs on it and no tail pipe at all. Part of the purchase was having it fixed. Car lot had a muffler shop put in a Dual In dual Out muffler and tail pipes out the side behind tires (we occasionally haul horses) I forget the muffler name...its a flowmaster knock off...lol. There is no x pipe or anything...far as i could tell from the website for the muffler there was not even internal to the muffler.
I have been planning to to a good TB clean...but its been so cold...Will try that this weekend. Can change fuel filter then also.
I have been planning to to a good TB clean...but its been so cold...Will try that this weekend. Can change fuel filter then also.
https://www.f150forum.com/f11/exhaus...re-myth-78102/
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I can try the O2 sensors. I guess that I always thought the O2 would throw a code if it was not working right?
I know that the X pipe would help...which is why i was glad the guy installed the muffler a little further forward...there is room to put one back where the y was. I just have not checked out what it would cost to have that done. To be honest the truck was running SOOOO much better than it did when it just had the cherry bombs I was thrilled with the work done.
I know that the X pipe would help...which is why i was glad the guy installed the muffler a little further forward...there is room to put one back where the y was. I just have not checked out what it would cost to have that done. To be honest the truck was running SOOOO much better than it did when it just had the cherry bombs I was thrilled with the work done.
