I know, another Poor gas mileage thread.

I have cleaned the maf.. unplugged the battery.. new plugs.. new air filter.. brakes are not hot.. used premium and regular..

i just got 16.2... lieometer says 18.5.. this is a V6!

I'm down to two possible scenarios, no CEL for 02 sensors.. but exhaust leak or too low of tire pressure, maybe?

can you really have bad o2 sensors with out a CEL, hate to drop the money and that not be it..
 
It's not impossible that it is your O2 sensor, but normally they fail gradually. It does not sound like that is what happened to you. If you do decide to change it, only the first one matters. The second one just checks the cat.

Also, premium fuel will do nothing for mileage, it just burns more money per gallon.
 
mizak82 said:
can you really have bad o2 sensors with out a CEL, hate to drop the money and that not be it..
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Yes. CEL only occurs when O2 reports out of range or inverted signal. O2 only makes fine adjustments when the RPMs are steady (such as highway driving), so if the sensor is completely toast, it'll throw a CEL. If it's not performing properly (eg. not doing it's job fast enough or reporting readings wrong), but still reporting signals in range, it won't throw a CEL.
 
mizak82 said:
Its like 200 bucks an 02 sensor.. and if I'm reading it wrong, its 2 02 sensors and 2 air fuel sensors?

thats a lot of money on a maybe...


ToyoDIY.com
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Typically, you'll replace upstream sensors first. They see the most abuse. I suggest looking on RockAuto and only going with Denso replacements! Denso is an OE manufacture.
 
throttle body is now cleaned.. did you guys re use your o ring gasket or did you get a new one when you took the throttle body off?


however all of the above is now done.. theoretically it should get the best gas mileage of its life.. everything has been cleaned like new, better plugs, better air filter, synthetic oils across the board..

anyways.. I guess we will see what happens with this tank of gas..
 
Check your spark plugs for oil. It would accumulate on the threads. The cause is a leaky valve cover gasket. And for the love of god would people stop using k&n filters??? You probably need to scrub your upper and lower intake manifold from all the crap and oil that the k&n spewed inside your engine.

Sent from my SAMSUNG-SM-T337A using Tapatalk
 
I can't seem to find much on o2 replacement. I'm reading different things. I see people mentioning only replacing one upstream sensor, but then I'm also reading that there are two upstream and two downstream. Can anyone clear this up ?
 
There are two sensors on each side of the engine for a total of four. The ones behind the cats are the o2 sensors. The ones in front of the cats are the air-fuel ratio sensors. The two fronts are the same part number and the two rears are the same. The fronts and rears are different sensors, however.
 
fdbyrne said:
There are two sensors on each side of the engine for a total of four. The ones behind the cats are the o2 sensors. The ones in front of the cats are the air-fuel ratio sensors. The two fronts are the same part number and the two rears are the same. The fronts and rears are different sensors, however.
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That's what I figured. Just wasn't sure if I should order two fronts or one front, but that clears it up. I'll get two.
 
well to make everyone feel better about their mileage i averaged 11.1 on the way to the OHV this weekend. i was fighting a 20-25mph headwind and running 75-80mph, but damn i dropped a lot with the jump to 35s from 33s. gears cant happen soon enough. i did average 14.3 on the way back though..... so yeah i guess thats ok?
 
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