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12 Posts
Discussion Starter #22
I've put the car on jack stands and in neutral. All wheels rotated freely.

Here is what I can recall doing so far:
  • wheels checked for free rotation.
  • TB cleaned
  • air filter replaced.
  • oil changed.
  • MAF cleaned (no change) then replaced.
  • plugs changed.
  • tire pressure checked multiple times by myself and once by a shop.
  • AF & o2 sensor replaced with Bosch units (no change in mpg or performance) and then originals re-installed.
Potential culprits left:
  • the tires (milestars) are not old, but one or more of them have a flat spot creating a very noisy ride, especially above 45 mph. I've put tires on a civic that were supposed to help fuel economy and maybe noticed a 1-2 mpg improvement, but can't say for certain. I've never had a set of tires cause poor mpg to my knowledge so I'm not sure replacing these would change anything.
  • I read in from another source that the honeycomb material in a CAT can break free clogging the exhaust and hurting performance/mpg. I haven't driven another 2.5l camry to compare, but acceleration seems good to me so I don't think there is anything clogging the exhaust system. I have no idea how I'd check for this beyond replacing the CAT, which would be terribly expensive and really a shot in the dark.
  • faulty fuel pressure regulator: i've read that these can go bad and allow too much fuel to pass by hurting mpg.
I'm confident that it is not my driving habits causing the poor fuel economy. Not sure if I mentioned this, but I contacted the prior owner who used the car for commuting. They said they would get 28mpg on average (mixed driving).

As someone above mentioned, I think I'll learn to use the scan tool more thoroughly and see if some additional data can lead me to a solution.

2012 Highlander Ltd
16 Posts
Use your scan tool to read and then post your ST and LT fuel trim readings.

go to and look at your specific Camry to view what real world mpg averages others are getting.
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