Slight Loss Of Power And Small Decrease In Gas Mileage

[immax01]

This didn't happened suddenly. It has just gradually gotten worse in the past 6 months. I feel like im towing something when im climbing up to 50mph, after that i cruise and even ride at 75 just fine, but it feels like i have slightly less power accelerating. Also im noticing about a 10% loss in gas mileage. I feel like these 2 symptoms are related because they started around the same time.

Recently I have been working on a few major scheduled maintenance projects. Between last week and this week, I will have changed my oil, my coolant, transmission fluid, change fuel filter, and replace both front o2 sensors( because i have a check engine light for one of them malfunctioning). I suspect my car's performance loss might be due to the o2 sensors, but i may be wrong. Anything else i can look into for this problem? Thanks!

[Lexusfreak]

I would add new spark plugs, an air filter & PCV valve to that list......that's a full tune up.

Tire pressure is correct?

[gbhrps]

Maybe you need to thrash on the engine for 10 minutes or so, or do a battery disconnect and reset the computer as well.

To clarify, many of today's cars have learning computers, that is that they learn your driving patterns and provide transmission shifts and engine performance to match accordingly. Myself, I do not drive a car hard at all. I never get into the accelerator or ask the car to do a downshift, unless I misjudge a traffic situation and need to keep from becoming a statistic. Consequently, my daily driver is very sedate at accelerating and shifting. I have in the past thrashed the car for short periods, or disconnected the battery to reset the system. Invariably whenever I drive the car next it is a changed machine performance wise, almost as dramatic as a complete tuneup.

My wife, on the other hand really drives her ES330, and its performance has not dropped from the day she purchased it, almost 100 000 km earlier.

For sure do all of the maintenance required and get a tune up. If that doesn't change the car's performance, try my suggestions. And if that doesn't perk her up, you need to see a techi who you know is very savvy at his job. Good Luck!