Bad 02 sensor?
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Bad 02 sensor?
My 94 F-150 5.0L automatic i bought in the late summer of this year. Now, during the summer i drove it to work everyday, and it seemed like it made fuel mileage like the average ford would (horrible). But lately it seems like it has been making even worse than just a few months ago. So i was just wondering if a bad 02 sensor could be the cause of this. The truck should make a little better fuel mileage then when it was stock because at the moment i am running true dual exhaust with Glasspacks, and no cats. So i figure that this should help a little bit. But it seems that there is something else wrong. So, today i bought a new fuel filter for it, but haven't had a chance to put it on yet. Also a few weeks ago i purchased a drop in K&N for it. I haven't really noticed much of a difference with the K&N, but my opinion is that there is something else wrong. Any help could be greatly appreciated thanks.
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Just a theory. I have a 250/460 that I did about the same thing to . While I noticed a slight performance increase my milage went down as well. I have changed my O2 sensor, EGR valve, EGR solonoid, PCV valve, air and fuel filters, plugs, wires, cap, rotor. All to no avail. I am starting to think that without the backpressure from the cat elements the EGR does not perform as well as it should and unburned F/A mixture is just going out the tail pipe instead of going back to the engine. I could be wrong but that is my guess. Any other opponions are welcome. Take care, Charlie....
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Yes i can see what you are saying that more air means more fuel burned, so what would recommend? Should i leave everything the same and just throw a set of aftermarket cats into there? Also, is there a way to test your 02 sensor to see if it is shot? Like i say, i bought the truck with all of the exhaust already tinkered with, so i can't say if it decreased or increased the mileage.
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Would a bad 02 sensor set off the check engine light? Because the other day when i was driving it the check engine light came on for a minute or two. I didn't think anything of it because i thought for sure it would be a dirty fuel filter, seeing as everything else was running properly.
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From: USA
Failing O2 sensors will often cause intermittent check-engine light. Eventually, when the sensor completely gives up the ghost, your light will just stay on. Least thats how it went on both my current F-150, and my old 94 Bronco.
And just my two cents, some performance upgrades can actually increase, rather than decrease vehicle economy. I know in my GF's Grand Marquis, adding the HO top-end to the motor increased her gas mileage by almost 4 miles per gallon. From what I've learned, its all about finding the right balance of weight versus power, and alot of the 80's trucks and cars were just really bad at that from stock.
The Admiral
And just my two cents, some performance upgrades can actually increase, rather than decrease vehicle economy. I know in my GF's Grand Marquis, adding the HO top-end to the motor increased her gas mileage by almost 4 miles per gallon. From what I've learned, its all about finding the right balance of weight versus power, and alot of the 80's trucks and cars were just really bad at that from stock.
The Admiral
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OK, well then that makes alot of sense. I hope that this is the problem, but from what i hear a new 02 sensor could set me back $100 atleast. So i think i will change the fuel filter first, and then if the light still comes on then i will put a different 02 sensor in the beast. So could an 02 sensor slowly fail over a long period of time, or will it just one day decide to conk out?
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I'm sure it can go either way, but in my personal experience, they have all gone slowly, over a series of months. I know my mothers 96 Dodge Stratus' O2 Sensor took almost 6 months for the Check Engine light to stay on as her O2 sensor slowly quit. Hope this has helped. I know in my old Bronco the O2 sensor ran me bout 85-90 bucks parts and labor at my mechanics shop, but I'ld be willing to bet somebody round here could give ya a decent how-to if ya wanted to do it yerself.
The Admiral
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Ok, well thanks guys for all your help, im really hopin that this is the problem, cause even when i first bought the truck i figured it should make a little better fuel mileage then what it is making. I remember in my mother's Chryslar Dynasty the 02 sensor went, and i believe that it was also a slow process of elimination. But yes im hoping that is my problem with this gas guzzling road warrior. but thanks again!
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From: Douglasville,GA
Originally Posted by Matti D
My 94 F-150 5.0L automatic i bought in the late summer of this year. Now, during the summer i drove it to work everyday, and it seemed like it made fuel mileage like the average ford would (horrible). But lately it seems like it has been making even worse than just a few months ago. So i was just wondering if a bad 02 sensor could be the cause of this. The truck should make a little better fuel mileage then when it was stock because at the moment i am running true dual exhaust with Glasspacks, and no cats. So i figure that this should help a little bit. But it seems that there is something else wrong. So, today i bought a new fuel filter for it, but haven't had a chance to put it on yet. Also a few weeks ago i purchased a drop in K&N for it. I haven't really noticed much of a difference with the K&N, but my opinion is that there is something else wrong. Any help could be greatly appreciated thanks.
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For about $30 you can buy an engine decoder and find out what your problems are. Well if adding large pipes and K & N Filter and all that stuff makes you lose fuel mileage then get a1-1/2 pipe and have then end enlarged to fit inside your pipes just past the muffler then you'll get back pressure back and still look good and sound good and have the best of both worlds
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Checking codes will tell you about and 02 sensor problem. It wont tell you about your fuel filter, fuel pump, etc. Also a clogged fuel filter would not decrease your milage, due to the fact that the amount of fuel going to the motor would be decreased. By all means change your fuel filter regularly because dirty filters create extra strain on the pumps making them fail faster, and its not a cheap fix or a nice job. Try doing your plug wires, plugs, distributor cap and rotor. These items will positively affect your milage and make your truck run smoother. Also when buying plugs, dont be fooled by the fancy four electrode exspensive ones for the reason of simple high school physics, electricity will only follow one path, which is the one with least resistance, so you are paying for four paths where only one will get used.
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