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Category: Lexus
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I have a 2006 LS430. In the last 2 months my mileage has

Customer Question

I have a 2006 LS430. In the last 2 months my mileage has dropped to less than 18 mpg to an average of 15 to 17.5 mpg on tank to tank basis. Prior to this (since 2013) mpg averaged 18 to 21 mpg on a tank by tank basis & for all of 2013, 2014, & 2016 to date I averaged 19.1 mpg annually.
Odometer is 103,220 plus & all maintenance have been performed. Next maintenance is at 105,500 miles. Tire pressures are 38 & 35 psi F & R respectively on Bridgestone EP422's. I use a mechanic who used to work at Lexus whose primary servicing is on Lexus & Toyota vehicles.
My research into the issue led me to possible air filter being dirty (haven't checked these yet), 2 O2 sensors have been changed due to CEL (done in prior servicing) & possible MAF issues (just found this "reference" on the internet & also by reading my OEM Lexus repair manuals).
Am I on the right track? Can you give me any details on my research to look for as well as any further items to consider.
I always try to do research before I ask my mechanic to check my car...he has been honest & straightforward with his responses so I trust him but I would like to "help" reduce time spent??? with anything I might find. Lexus has been significantly more expensive to deal with & very non-informative about problems & miscellaneous issues.
Submitted: 1 year ago.
Category: Lexus
Expert:  john -aka eauto replied 1 year ago.

have the spark plugs been changed?

Customer: replied 1 year ago.
Customer: replied 1 year ago.
your questioning whether spark plugs were changed is no response as the change in spark plugs is carried out in the normal maintenance steps well prior to this current question. if this is your only response then it is not worth the cost of $23 as it offers no help whatsoever.
Expert:  scionking replied 1 year ago.

Hello different expert here, would you like a second opinion from me?

Expert:  scionking replied 1 year ago.

A Mass air flow sensor cleaning is probably a good idea. Dirt can build up on the senor giving a false voltage reading to the engine computer, with this false reading the computer gives the incorrect amount of fuel to the engine.

I'm going to provide a list of what I think should be inspected.

Air pressure in tires( I'm sure you or mechanic check this) -can cause increased rolling resistance, there for needing more fuel to push the car

Tire alignment- -can cause increased rolling resistance, there for needing more fuel to push the car.

Sticking brake caliper components- acts as if brakes are slightly applied, also causes extra force to move car forward.

Partially clogging catalytic converters- not enough to set a check engine light, but work the same as a dirty air filter, as an air filter can restrict air flow into the engine the catalytic converters can restrict air out of the engine.

Wheel bearing wear- although usually accompanied by a noise, wheel bearing were can also cause the car to no free wheel as easily causing more force to move the vehicle.

Fuel injectors and carbon build up on intake valves- over time fuel injectors can not provide a less then optimal spray of fuel resulting in less atomization of the fuel, this can also occur with carbon build up on the valves, they act as a sponge so less fuel gets into the engine properly atomized.

These are just the top items that I would start with, If you want to discuss these further, or more elaboration on these please let me know and I would be more then happy to help.

Expert:  scionking replied 1 year ago.

Hello just checking in to see if you would like to discuss any of these items further?

Expert:  scionking replied 1 year ago.

Please accept my answer if it has helped, if you need further assistance please post follow up questions so I can assist further. If you accept my answer please rate the level of service provided today.