Ricanlexus

Hey im new to this i have a problem my es is only getting an average of 8 to 10 miles a gallon and thats crazy i thought it was because i always drove fast but ive been doing the speed limit and to no avail. Do you think it could be my o2 sensors?

lexusk8

Welcome to the club.

There can be a lot of reasons why you are getting poor mileage. Dirty fuel injectors, air filter, O2 sensors, high use of A/C, driving with a lead foot, tire pressure (but not the only indicator for the mileage). Try to approach these factors, especially the fuel injectors, and see if any of them make a difference.

Pheonix

Most likely bad o2 sensors. Test their output & responce time with a volt meter.
Get access to a scanner/logger & check what the fuel trims are also.



Also make sure the CEL/MIL isn't on, or has burned out, or been on in the past.
Limp mode will dump enough fuel to bring gas mileage into the 5-10mpg range.




The speed limit has nothing to do with economy. You can drive the speedlimit all you want and go from the 20-25mpg that's common down to under 20 fairly easily.

Ricanlexus

What do you mean limp mode? what is the CEL/MIL?

Pheonix

A limp mode is what you call when the ECU get's into a fail safe mode. It's designed to let the engine/transmission survive long enough to get the car safely somewhere to service.

In a nutshell, all ignition timing is heavily retarded, the computer dumps as much fuel in the engine as possible, and still run smoothely. If it's bad enough overdrive gears can be locked out, and the ignition & fuel is controlled to keep the engine from easily revving over 4000rpm.


CEL Check Engine Light
MIL Malfunction Indicator Light

Ricanlexus

o ok thanks alot im guessing it would be the sensors then because i put new filters and none of the lights come on