Has anyone here ever replaced the O2 sensors on their truck?? Mine has 57,000 miles and fuel mileage has dropped from about 20 to 16 on the highway. Also, power is slowly decreasing. Everybody tells me it's the 02 sensors. Check engine light is not on. I hear they are pretty high, so before I dive in I would like some feedback. I have 2 O2 sensors (one on each manifold) and a catalyst monitoring sensor (according to shop manual....looks like an 02 sensor to me...) after the first cat. Does it need replacing, too? Hope not....$$$ It's a 96' 5.0L.

-Hank

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1996 F-150 (3/96-old style)XLT, 302, 5sp. Toreador Red CC, Tow Pkg, Optional Payload Pkg, HD susp., Flowmaster 40 series, "Duals",
Raven Cap, Bumper Guards, Hood Ornament, Unity Lights, Jet Chip, K&N, B&M Shift ****, Hidden Hitch w/ Ford Motorsports Cover,...etc.

 

i have a 95 5.0. i only have one o2 sensor right before the first cat..why do i not have 2 of them....i replaced the one i had and noticed a little improvement but not much. mine had 65,000 miles on it..not too bad money wise, it was 43.00 at autozone..

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95 F-150 s/c XLT short 5.0 4x2 4R70W trans. 3.55
Cat-back duels with flo-pro and echo tips
K&N FIPK, Superchip
New dunlop rover touring 255/70R15
Accel 8.8 custom wires, accel superstock coil, accel cap and rotor
motorcraft platnium plugs
Soon to get a tint job, and maybe a pair of nerf bars

 

95FordMan - The concept of putting an extra O2 sensor AFTER a cat, came in OBD II (Onboard Diagnostics II). This was to meet a new government mandate for an emissions system to be able to diagnose itself, recognize failures of emissions equipment, and turn on a Malfunction Indicator Light (MIL). 49 state vehicles started this in '96, but California may have started this in '95 (I'm not certain on CA's start date).
You have a '95 49-state, so you can use a cheap code reader to recall any codes that may set your Check Engine (MIL) light. In that respect, be happy you have a 95! It is much more user-friendly for maintenance!

 

They started Platnum plugs and also the OBD2 on 1996 models.

I replaced both of mine and payed the 43 at autozone, and noticed an improvment on both. Idle, mpgs and performace inproved. I talked to a friend and he told me that cold and wet weather is the cause of the sensor wearing out.

 

Thanks for the replies!
I'm going to replace the two in the manifolds. Anyone think I should replace the third one after the cat?
Pastmaster, what mileage did you replace yours at?

-Hank

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1996 F-150 (3/96-old style)XLT, 302, 5sp. Toreador Red CC, Tow Pkg, Optional Payload Pkg, HD susp., Flowmaster 40 series, "Duals",
Raven Cap, Bumper Guards, Hood Ornament, Unity Lights, Jet Chip, K&N, B&M Shift ****, Hidden Hitch w/ Ford Motorsports Cover,...etc.

 

I already had an exhaust,chip, and a few other mods, but I'll guess about 2-4? I myself don't understand why the truck had 2 sensors, unless it tested before/after exhaust and adjusted as needed to.

 

Well,

Thanks for all the replies!! I just priced my O2 sensors (all THREE of them!!)...anyway the cheapest I could find them was $71 each!! Turns out they changed them in 96' or something. I am taking it into the shop on Wed. morning. They want $35 for a diagnostic scan. I figure that's better than $213 O2 sensors that I'm not sure about. I hate taking my truck to the shop. I'm a big do-it-yourselfer and it hurts my pride. Truck seems to be gradually losing power and mileage. I'll let yall know what it turns out to be.

-Hank

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1996 F-150 (3/96-old style)XLT, 302, 5sp. Toreador Red CC, Tow Pkg, Optional Payload Pkg, HD susp., Flowmaster 40 series, "Duals",
Raven Cap, Bumper Guards, Hood Ornament, Unity Lights, Jet Chip, K&N, B&M Shift ****, Hidden Hitch w/ Ford Motorsports Cover,...etc.

 

Hank, I have a 1996 F150 w/ 302 and you description sounds almost identical to mine. My truck has been getting around 12mpg since I bought it w/ 23,000 miles. It is now knocking a little when I accelerate hard up hills and bridges. An employee at the local auto parts store told me that the O2 sensor would be the answer to the poor milage. I always asume that everyone knows more than me (because they probably do), but the dash light was not on and I was not certain. I would be very interested in knowing how it turns out for you. Thanks Alot -- Martin

 

Hank, I forgot to mention my truck now has 58,000 miles on it. I am not sure if mine has 2 or 3 O2 sensors. How will I find out? Thanks again -- Martin

 

Martin,

If your truck is a 96' it has 3 O2 sensors. I found out it is because of OBDII (a new type of computer system used 96' and up). Your truck should have 1 O2 sensor in each of the two exhaust manifolds and one after the first cat convertor (49-states) or 1 after the last cat (california). The two in the manifolds measure the O2 concentration in the exhaust and control the fuel mixture. The last one just measures how well the cat is working. Basically boils down to tighter emissions. BTW: I've noticed that mine has a slight ping also.....I'll let you know what happens. Appointment is tomorrow morning at 8.
-Hank

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1996 F-150 (3/96-old style)XLT, 302, 5sp. Toreador Red CC, Tow Pkg, Optional Payload Pkg, HD susp., Flowmaster 40 series, "Duals",
Raven Cap, Bumper Guards, Hood Ornament, Unity Lights, Jet Chip, K&N, B&M Shift ****, Hidden Hitch w/ Ford Motorsports Cover,...etc.

 

Well,

I just got back from the garage. The mechanic scanned the computer and sensors and found nothing....Said everything was just fine. Doesn't know why the check engine light came on. It only stayed on a day so he thinks it didn't have time to set a code. He said the poor(er) mileage was due to my K&N FIPK. He said that all of the extra air is causing the computer to richen the fuel mixture hence the poor mileage. I find it hard to beleive I lost 5 mpg with the addition of the FIPK. I love the power difference, though- I guess it's a trade-off. But I didn't notice a 5mpg difference in power. He said the poor power when towing was due to my 3.08 rear and the slow nature of the 302. O2 sensors checked good. I find it hard to beleive that an F-150 with any setup would have problems with a 1000 pound utility trailer....i'm very confused. I've pulled equal weight with an 85' Dodge 318 that'll do circles around my 302. Guess it's a gearing difference. Think i'll be checking on some gears....

-Hank

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1996 F-150 (3/96-old style)XLT, 302, 5sp. Toreador Red CC, Tow Pkg, Optional Payload Pkg, HD susp., Flowmaster 40 series, "Duals",
Raven Cap, Bumper Guards, Hood Ornament, Unity Lights, Jet Chip, K&N, B&M Shift ****, Hidden Hitch w/ Ford Motorsports Cover,...etc.

 

I was reading about replacing the O2 sensor. I was wondering, I have a 95 5.0 with 140,000 miles on it. I've had it for the last 110,000 and I don't think we've ever replaced it. I don't notice anything different, but should I replace it any way, will it help?
Thanks

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Nate
95 F150 5.0 E4OD
SC SB 4X2 30X9.5R15
nate95@f150guy.com

 

I would advise it. Recommend intervals is 60k. So your twice over it. I noticed about 2-3 mpg better, although I honestly didn't recognize better performance.

 

Hank
I would have to argue with the mechanic that told you your mileage loss is due to your FIPK. Unless you are driving it harder because you are having fun with the added power, this is a load of crap. The mass air and computer will cause more fuel to enter the system under higher air flow situations. For normal driving I have never seen a basic intake system like this actually lower mileage. Just my 2 cents. Also even with that gear ratio, a 1000 lb trailer shouldn't make the truck work that hard. I have the 3.31 in my 95 5.0, and it does just fine.

 

It has to be gearing. A friend had a 85 318 1/2ton dodge as a farm truck, it was slower than he**. I have a 93 302 3.55 gears, it will pull 5500 lbs fine. Maybe with a little sweat...