avalon42

iTrader: (1)

I notice that when I switched from ARCO to SHELL gas, my MPG improved dramatically. I'm getting some of my older MPG numbers (400-420 miles on a full tank).

I did do a minor tune-up (spark plugs, wires, cap, rotor, both ignition coils), but I was thinking it maybe time for the o2 sensors to squeeze out some additional pep.

Anyone here notice anything after changing their o2 sensors? Also, what did you use? (OEM, Walker, or Universal)

3UZFTE

Not sure who Arco is, however Shell is a Top teir gasoline so you will get the most out of their gas as opposed to others. Do you have a CEL? If not, your O2 sensors are functioning fine, and I wouldn't just through another $100 in there to save a few at the pump. I would awesome the majority of your MPG came from your tune-up. However if you are just chomping at the bits to get it done, I would go Bosch universal and then cut and splice the older plugs onto the new sensors. You can use whatever you would like, I would just save a few bucks where you can.

python

iTrader: (4)

oxygen sensors do not have to go out completely(causing a CEL to come on) for them to gradually cause a decrease in gas mileage. it isnt going to be a drastic decrease but over time the 02 sensors will start detecting more air in the exhaust and start to compensate for this by dumping more fuel. a failing coolant temp senor (ect) will also cause the ecm to dump more fuel than is needed. im in no way contradicting u
3UZFTE,just clearing up what u said to begin with.

3UZFTE

I wouldn't think that, I only add my 2 cents and let the OP decide if should use it as they see fit. I mean your knowledge isn't any less informative than mine, I am glad more people can chime in, I by no means am the final word or say. I would just be suspect of it creating a major issue, especially after you just noticed a major increase in your mileage, that to me kind of sounds like they are adjusting accordingly. Again, glad to see someone else chime in.

jcp2000

its not from the o2 sensor your getting better mpg's cause you went from water to gasoline! why on earth would you use cheap A word arco!?! for me i dont even use shell cause imo it burns fast i only use 76 gasoline and if i have to mobile comes in at a close 2nd! i never even think about putting in anything else

Spacepig

If you've had a drop in mileage in the last couple of months and you're in CA, don't forget that we're stuck with a the reformulated winter gas, which can cost you 10% or so of your MPG.

treeman

I recently changed the o2 sensors( Bosch) in my 94 LS400 and have noticed a considerable difference in mpg. My cel came on and diagnostics showed code 25, Now the morning the cel came on, I acquired a miss before cel and after changing sensors I still have a miss. I have checked diagnostics again and it shows nothing. If anyone has any input let me know.
me the tree

python

iTrader: (4)

a misfire? when? at idle but smooths out at higher rpms? ohm out ur coils

treeman

all the time, the car seems to lope at idle especially but never really smooths out. Im gonna clean throttle body and maf, maybe change plugs. OHM? dont understand.

python

iTrader: (4)

resistance check between terminal connections

avalon42

iTrader: (1)

Considerable as in bad? Sounds like it from your description, but I suspect it has to do with something else.

Where did you source the sensors from?

treeman

I got the sensors from a local automotives store, but considerably good, my mpg improved, the miss hasnt changed, ive read other threads saying clean throttle body and clean maf, so im gonna start there then maybe new plugs and wires. I just bought this car after it set up for almost a year and there have been a number of issues: heat only blows cold and ive just about given up there, cd changer will not play but has power and no err codes, now this miss. I know that soon I will have a sweet ride though. If any one has any input on these issues please feel free to let me know, the heat is definitely a problem right now cause we have about ten inches of snow on the ground here. Had to break out the 95 4runner,
me the tree,

avalon42

iTrader: (1)

I had a minor miss on my LS (plus poor fuel economy), turned out to be a dying ignition coil. I had already did a minor tune-up which helped but didn't nail it like the coil replacement.

treeman

Thanks Avalon42, I will be sure and check your recommendation.

yahoo_san

Did thoes noticable help your milage? I'm also looking to increase my mpg. I'm getting around 13mpg currently and looking at less than 250 to the tank (and thats with driving incredibly light, rarly going over 2k rpm). With gas prices @ $3.51 per gallon, I've already started catching the bus and I'm even considering selling my LS. I just changed spark plugs last weekend, some pretty clean denso plugs came out (just bought the car last nov.), the wires, cap and rotor looked pretty dirty though. The car pulls fine so im not suspecting theyre hurting the mpg, but I'm not interested in dumping money into this car unless I know theres a possiblility that I might be able to make at least 300 to the tank.

Any responces would be apperciated, Thanks!

Oh, I also fill up at Chevron if that makes any difference..