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big mpg drop

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Old Feb 1, 2011 | 03:49 PM
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87hillbillyoter's Avatar
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From: N. Lake Tahoe/Chico CA
big mpg drop

hey guys, i just noticed my mpg went from ok to terrible within the past few months. i used to get 18 with my 33s on, now im only getting 12 . ive changed the oil, plugs, air filter, cleaned the carb, and put fuel additive through the tank. i plan on seafoaming it next fill up, but i doubt that will give me a 6mpg gain. is it because of the winter mixture of fuel? could it be the fuel filter? any suggestions would be great. thanks yall!

Last edited by 87hillbillyoter; Feb 1, 2011 at 03:51 PM.
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Old Feb 1, 2011 | 03:53 PM
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From: N. Lake Tahoe/Chico CA
oh yea the fuel additive that i ran was RxP gas kicker- http://www.rxp.com/
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Old Feb 1, 2011 | 04:22 PM
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My mileage took a 4 mpg drop and it turned out to be the a diverter valve in the air cleaner intake . It is the one that diverts hot air from the exhaust manifold into the air cleaner, it was pulling hot air all the time. To fix it I unplugged the vacuum line at the diaphragm and plugged it.
After a couple years of driving I have not noticed any bad effect from it being inactive .
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Old Feb 1, 2011 | 04:25 PM
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mine was the same thing swampfox said.....but mine wouldn't idle worth a crap..lol
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Old Feb 1, 2011 | 04:26 PM
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From: Oceanside, CA.
Mine dropped also in the last 2 weeks. I keep a log book of every fill up with MPG and I am down about 2.5 to 3 MPG since late January. My commute does not change and if anything traffic on the freeways has been less lately.

I have a brand new fuel filter in my truck as well as adjusted the valves, new TPS and new EGR.

I think its just the winter blend. Gas prices are going up and the gas companies know we get less mileage on their winter blend so 1+1=$$$ to them.
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Old Feb 1, 2011 | 04:33 PM
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From: Vian, OK
check your fuel filter there hillbilly...


you can get to it through the passenger side rear fender if i remember correctly
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Old Feb 1, 2011 | 04:47 PM
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From: N. Lake Tahoe/Chico CA
Originally Posted by swampfox
My mileage took a 4 mpg drop and it turned out to be the a diverter valve in the air cleaner intake . It is the one that diverts hot air from the exhaust manifold into the air cleaner, it was pulling hot air all the time. To fix it I unplugged the vacuum line at the diaphragm and plugged it.
After a couple years of driving I have not noticed any bad effect from it being inactive .
do you have any pics of said object? i get the general area i just dont know exactly where you are talking about haha. i forgot to say that my truck runs perfectly. idles perfectly and everything
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Old Feb 1, 2011 | 05:00 PM
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From: Nw Arkansas
I don't have a picture but it is on the air intake inlet , There is a vac diaphragm on the top side and a air inlet just above the exhaust manifold on the under side. There is suppose to be an bendable hose between the exhaust and the air intake,but most of the time they are gone. But it still re sticks air flow and gets more hot air in even with out the bendable hose.
My truck ran good also ,except for it was not as responsive.

Last edited by swampfox; Feb 1, 2011 at 05:02 PM.
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