Loss of MPG - Toyota Yaris Forums

RETRO · 01-09-2015, 03:14 PM

I know these post come up often. I have a 2008 Yaris HB. I bought used 5 years ago with 24k miles. For 4 years I got 41-42 mpg in the summer and 39-40 mpg in the wither. Dec 2013 I noticed my mpg dropping.I lost about 2 mpg per tank.I have changed the plugs that made no difference. Today I am getting 33 mpg in the winter and 36 in the summer. I use the same station for years. I now am using another station and getting the same about 32-33 mpg.My driving is the same and nothing has changed on it. really confused on this car runs smooth just not sure what else to do.Suggestions Thanks.

Bluevitz-rs · 01-09-2015, 03:48 PM

It's possible the AFR sensor is getting lazy. My '05 was getting the same way except i was getting random codes regarding running too lean and misfires. So I had a friend perform an active test on the cars fuel enrichment while monitoring the O2 reading and it indicated the sensor was not reading properly anymore. Replaced it and gained 100-150km per tank.

Might be something to concider.

It might also be that the fuel companies are adding more and more ethanol content to the fuel mix.

*Astroman* · 01-09-2015, 03:51 PM

This was posted in the wrong section of the forum, moved it to the correct one.

RETRO · 01-26-2015, 04:31 PM

I've clean the MAF,throttle body. Ran seafoam through the brake booster and tank. Still no improvement.Thats my thinking higher % of ethanol in gas.

Bluevitz-rs · 01-26-2015, 04:33 PM

Have you monitored the A/F sensor to make certain it's reading correctly?

RETRO · 01-26-2015, 08:31 PM

Quote:

Originally Posted by Bluevitz-rs

Have you monitored the A/F sensor to make certain it's reading correctly?

I have not and not sure how to.

Bluevitz-rs · 01-26-2015, 10:27 PM

You'll need a wiring diagram. You might be able to back probe the OBD connector inside the car with a volt meter to take the reading while you drive the car.

CTScott might be able to help.

RETRO · 02-05-2015, 06:50 PM

it is reading 0.2 volts at idle? what is the correct voltage?

01-09-2015, 03:14 PM	#1
RETRO Drives: 2008 Yaris Hatchback Join Date: Jan 2010 Location: Alabama Posts: 64	Loss of MPG I know these post come up often. I have a 2008 Yaris HB. I bought used 5 years ago with 24k miles. For 4 years I got 41-42 mpg in the summer and 39-40 mpg in the wither. Dec 2013 I noticed my mpg dropping.I lost about 2 mpg per tank.I have changed the plugs that made no difference. Today I am getting 33 mpg in the winter and 36 in the summer. I use the same station for years. I now am using another station and getting the same about 32-33 mpg.My driving is the same and nothing has changed on it. really confused on this car runs smooth just not sure what else to do.Suggestions Thanks.

01-09-2015, 03:51 PM	#3
Astroman Modded Moderator View User's Garage Drives: 07 Toyota Yaris, 71 Galaxie Join Date: Mar 2007 Location: Wenatchee, WA Posts: 3,670	This was posted in the wrong section of the forum, moved it to the correct one. __________________ Please visit my online store for computer stuff and Official Yarisworld decals!

02-05-2015, 06:50 PM	#8
RETRO Drives: 2008 Yaris Hatchback Join Date: Jan 2010 Location: Alabama Posts: 64	it is reading 0.2 volts at idle? what is the correct voltage? Last edited by RETRO; 02-05-2015 at 07:20 PM.

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01-09-2015, 03:48 PM	#2
Bluevitz-rs 1NZ-6spd View User's Garage Drives: '05 6-Spd Vitz RS Join Date: Oct 2008 Location: Oshawa, Ontario, Canada Posts: 2,967	It's possible the AFR sensor is getting lazy. My '05 was getting the same way except i was getting random codes regarding running too lean and misfires. So I had a friend perform an active test on the cars fuel enrichment while monitoring the O2 reading and it indicated the sensor was not reading properly anymore. Replaced it and gained 100-150km per tank. Might be something to concider. It might also be that the fuel companies are adding more and more ethanol content to the fuel mix.

01-26-2015, 04:31 PM	#4
RETRO Drives: 2008 Yaris Hatchback Join Date: Jan 2010 Location: Alabama Posts: 64	I've clean the MAF,throttle body. Ran seafoam through the brake booster and tank. Still no improvement.Thats my thinking higher % of ethanol in gas.

01-26-2015, 04:33 PM	#5
Bluevitz-rs 1NZ-6spd View User's Garage Drives: '05 6-Spd Vitz RS Join Date: Oct 2008 Location: Oshawa, Ontario, Canada Posts: 2,967	Have you monitored the A/F sensor to make certain it's reading correctly?

01-26-2015, 10:27 PM	#7
Bluevitz-rs 1NZ-6spd View User's Garage Drives: '05 6-Spd Vitz RS Join Date: Oct 2008 Location: Oshawa, Ontario, Canada Posts: 2,967	You'll need a wiring diagram. You might be able to back probe the OBD connector inside the car with a volt meter to take the reading while you drive the car. CTScott might be able to help.