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gas mpg

B

bigmcgiv

NAXJA Forum User
Location
wilkes-barre pa
i have a 94 with a 4.0 Ho . is ther a mod or fuel saver chip or resistor that works on it. i ony get 10 mpg. i hear alot of people say change the o2 but my cat has been punched out. will a new o2 help. also i have a cracked manifold too. i hope someone can help im looking for suggestions before wasting money on parts that wont change my mpg for the better
 
I change my 02 an got better mpg... Went from 9/10 to 15 around town.. I don't drive freeway to much.. this weekend i'm going for a day run about 90 min away..This will be all freeway, then i refuel my heep to offroad
 
yes i did a tune-up. the cracked manifole i just found out about 3-4 days and plan to get welded. but i wasnt shure if having a convertor punched out made a difference. if i should change the o2 sensor.
 
I'm on the exact same boat as you. Im getting about 13 or les MPG. I have a cracked manifold and both of my O2 sensors are out. So it's running alot more rich than is should. They actually make a header for a our jeep that is stronger and wont crack. And it isnt as much as a real header. Who cares if it doesnt give you that much more HP and doesnt look as nice. Its like under 130 bucks I belive. I can try to find if you want.
 
ok i got the o2 yesterday im putting that in tommorow and i got a manifold that i got from a customer that just took one off a 95 and im taking it to have it welded so i could put it on.
 
Sounds like your on the right track. Manifold leaks can introduce excess air to the O2 sensor tricking the O2 sensor / ECU into addiing more fuel than it really needs, if the O2 sensor is working. A bad O2 sensor will keep the ECU running real rich all the time and will damage a good Cat converter. Not having a cat converter will not hurt a good O2 sensor, but some would say the lack of back pressure might affect the flow in and out through the engine and could cause unwanted side effects, that might affect mileage.
 
well i just change it the o2 sensor. i find out in a week or so. it got to 55 degrees today here its heat wave. so i did it of corse like everything on this has been buggard by someone before me they cross threaded the old one. i didnt have a tap so i thread file it and got it back in.
 
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