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· Too Soon, Junior!
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Discussion Starter · #1 ·
So update on my original question where I asked why I was getting 11 mpgs. I returned the tune to stock, and gas mileage is still horrid. Spark plugs, fuel filter, air filter, etc. have all been changed within the last 6 months so I'm not going to sweat the little details. Gas mileage dropped after I had my o/r X pipe installed and I remember seriously stretching the front sensors to go into the pipe. This may have damaged them though the car isn't throwing a code.

Would replacing the front O2's be the most obvious solution to solving my gas mileage dilemma?
 

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I thought that the O2 sensors only read the levels..too rich too lean. But i just searched real quick and found an article saying that if they do read wrong due to faulty wires than it will affect your MPG by trying to adjust something that isn't even wrong.

But i never noticed any thing wrong when i went to a o/r x with out my tune?? Maybe sense yours is damaged its just way outa wack?
 

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the sensors read the air/fuel ratio, so if theyre bad/reading wrong then they will force the fuel injectors to make the gas leaner/richer depending on how its reading, of course causing the car to not run as well plus causing bad gas mileage

but the O2 sensors are psycho sensitive in the mustangs (atleast the ones ive delt with) so if there was something wrong with them it should have thrown code. id put some injection cleaner in there first and see if that doesnt help first
 

· Boost gets you laid
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i would go ahead and replace them. i've never gotten below 16mpg with my car and its heavily modded. you're running super rich from the sounds of it.
 

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I remember seriously stretching the front sensors to go into the pipe
do you not have o2 extensions?? if not it might be a seriously good idea to do so. check the harness and check the fuse for the 12v heater wires as well, for if that fuse is blown you might have a short somewhere.
 

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If I understand them correctly, O2 sensors before the cats are for monitoring A/F ratio. Any O2 Sensors after the cats are just to see if your cats are working. The rear sensors would not be my first place I'd look.

This may seem too obvious,but are you hole-shotting everytime you start out? What do your plugs look like?
 

· Too Soon, Junior!
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4,259 Posts
Discussion Starter · #9 ·
It started getting bad gas mileage after the midpipe was put in. The plugs all look excellent, last time I changed the plugs they had 20,000 miles on them and looked like they were put in last week. I'll check the fuses as ford6693 suggested and go ahead and change the O2 sensors. Should I go ahead and order the extensions too?
 

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id def change th eo2 sensors. i had the same problem, im getting 14mpg last time i checked and both my o2 sensors were bad.... i replaced them but have yet to check my mileage
 
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