shuiyuan

my 94 es300 is getting 17mpg on 70% highway on 30% local driving without AC. i did some search on the forum but didn't find any answer because i ran the ECU code there is nothing wrong. some times P0402 Excessive EGR flow comes on once a while it will come off itself in 1 day. my question is even the ECU didn't indicate the o2 sensors or pcv valves have problem should i change them anyway? any other stuff will cause low mpg?

BadViper22

Check your O2 sensors, buy a can of intake cleaner and clean out your entire plenum and everything attached to it. then clean your MAF with MAF cleaner only.

sonyman

To get your mileage back up you'd probably spend more tuning up the car than you'd recoup from the gas savings. Your mileage isn't that far off either.

shuiyuan

i changed the spark plugs and PCV valve. mpg seems getting better. but the cel came on tomorrow says the o2 on the bank 1 needs be replaced, i know o2 sensors are something will decrease your mpg. do you know where i can get some cheap o2 sensors? Bosch or Denso brands

BadViper22

Don't know where, but +1 for only Densos.

llcoolpass

the bosch work fine, the universal part

you just crimp or solder to plug of OE part... keep same length and nothing will be different.

I get 20 to 21 mpg 50/50 [and that 50 is high speed, so its actually quite good mpg]