I ran this last tank with no O2... too lazy too hook it back up when the wire came off mixed with no time and a little curiosity

first a little background on the car
RB header, mid pipe and rusted stock cat back with more exhuast leaks through the whole system then I can count (stock cat back needs replaced and the mid pipe don't think is the greatest weld)
also have a K&N style filter with the stock tubing replaced by PVC piping
203k miles on the car
TB mod
a tranny that needs replaced and is prolly low on oil
some spark plugs that could prolly be replaced
six port actuator that sticks on the front rotor
some compression last time I check (Around 185k miles) of 85-90 for the rear and 100-110 for the front rotor
a tps that could use a little adjusting. not much just a tad here or there as well as replaced being it has a small bump in resistance
and some mobile 1 10w30 oil

ran the car the whole tank plus with 2 minor stops because gas was almost out and needed to get home


total of 17.999 gallons of gas
1.005 gallons of first minr fill
2.151 gallons for the second minor fill
14.873gallons for the last final complete fill her up
went a total of 429.1 miles


comes to 23.84mpg

whats up
everyone kept telling me I would get I would get something like 10mpg with no O2
my car isn't in the greatest of shape right now since I had no job to take care of the poor car though least hta is changing
and by putting a O2 sensor on my car I don't really see the gas mileage going up that much so anyone care to explain this?

 

In my experience fuel consumption increases by ~5% with the O2 sensor disconnected. Not a huge amount, but I don't like chucking away money for no good reason.

 

no o2 sensor makes that damn check light pop up on the idiot cluster....oh and you woulda got like 25-26 with an o2 :p

what i've heard is like 2-3 mpg freeway is what the o2 will get you. i got 25-26 on my long trips.

what he said

 

S4's don't have that problem.

 

If you hardly ever drive in closed loop, then the O2 sensor has virtually no effect.

 

I assume you mean any more moneyfor no good reason besides your car.





but hey bro those are also highway miles? Yes well there you go. what do you get city? i can tell you that my 88 gxl with basically the same mods with a race pipe instead of a highflo cat and a catback, my 5th &6th ports modded, and started the take off some of the pollution ****, i get anywhere from 13-15 miles per gallon in the city. lates matt22

 

lol matt you also do 120mph in third :p
just giving you crap


I can see the 5% or so
but just heard from others here and locally telling me I would get crap for mileage
granted most of it was hwy miles but there was still a decent amount of city in there around 130-150miles or so of that 430miles was city
not much but eh


still going to hook the O2 back up though



and also wonder why the hell the O2 reads negative voltage when under decel

 

As Aaron said, it won't make much difference if you don't do much driving in closed-loop. Closed-loop is only activated at light load and constant speeds, so it makes much greater difference to highway fuel consumption than city fuel consumption. Most of my driving is city, hence the small difference.

Definitely hook it back up. Any fuel saving is a good thing.

 

I agree will hook it back up and most of the driving would be in closed loop I assume being it is most freeway mileage

but any ideas why I hit negative voltage on the O2 sensor?

and what do you expect my gas mileage to go up to using the O2?

 

You probably just had the multimeter's leads the wrong way around.

 

nope the leads where right
at idle it reads around .7
most cruise situations around .25-.45v
but under decel or shifting gears it reads -.1v