Need some help

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Eric08

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02 5.4L Eddie Bauer expedition recently changed oil and filter, fuel filter, air filter, ran sea foam through intake and gas tank, gas mileage increased from 9.6 mpg to 15.5 mpg after a week it has went back down to 11.9 mpg and is sluggish on take off at times and and doesn’t have the acceleration it should. Vehicle currently has 155k miles on it and I’m about to change the transmission filter add exhaust and a nice intake. Any info on why it could drop back down like that would be great. I love this truck and want it to stay around for a long time
 
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Eric08

Eric08

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I spoke with a friend of mine and he agreed that could be the problem so I think next week sometime I’m just gonna drop the cats and do straights with a thrush welded muffler. If anybody else has done this set up it would be great to know how it worked out
 

DASAGT

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I had this problem once you had bad gas and if you let the tank get low you could have picked junk in the filter change out the fuel filter first and then check the cats if the problem persists my truck has a 160K on it.
 

stamp11127

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Drop the cats and you will get a CEL from the cat efficiency being out of range. Fuel trim may go out of range, performance and economy may also be effected since the ecm is trying to limit emissions.

Use a temp gun on them when they are up to temp, really hot usually means they have bit the dust if I remember correctly.
 

John Christopher

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Scotty Kilmer has a video on cats. I believe it's 1 gallon of lacquer thinner to 9 gallons of gas. Run it through the engine and it's supposed to clean the cat. Check it out it may help
 
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Eric08

Eric08

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Man that lacquer thinner is a great idea! I’m gonna try that next week see if that helps. The truck drives great I average 11.9 mpg in the country and 15.6 on the highway but take off is slow and staggered at times. It makes me think of a runner with a parachute on his back
 

toomanytoys

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If you are dead set on removing the cats you will need a pair of MIL eliminators to keep the light off. They are available at American Muscle and most other performance shops. Plug and play. If the heat shield on the cats has a blue spot then the cat is on its way out. Just remember- if you pull the cats and you get caught it’s a minimum $2500 fine
 
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Eric08

Eric08

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If you are dead set on removing the cats you will need a pair of MIL eliminators to keep the light off. They are available at American Muscle and most other performance shops. Plug and play. If the heat shield on the cats has a blue spot then the cat is on its way out. Just remember- if you pull the cats and you get caught it’s a minimum $2500 fine
Well I don’t think there is a fine for that ky but I’m not sure. Now I have a new problem. I can put the gas peddle to the floor and it doesn’t give any extra acceleration. It don’t open up or put you back or show any take off. The engine doesn’t even seem to know I’m giving it gas also my mileage has went way down again. Any advice?
 
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