YoshiUK

Hello, first time posting here.

Was looking for some assistance/knowledge from folks who have worked on these cars before. I've got a 2005 Lexus RX300 and it recently started having a bit of a rough idle. RPM sat around 1000, slight vibration in the steering wheel. Additionally she's gotten really sluggish accelerating, and my fuel economy has dropped from the low 20s where it normally sits to 13-16.

I pulled codes and nothing is posting. My initial thoughts were an air/fuel sensor but wanted to see if anyone else here had run into anything similar in the past. Thanks for any information or assistance you can provide.

matts6887

just a thought; have you tried cleaning out the throttle body? because what can happen is after awhile; deposits, etc; can clog up the "butterfly" in the throttle body and after so many miles of driving(not totally sure about how many but i think it may depend on driving conditions, enviroment etc) I would take off the air intake "hose" and take some cleaner made specifically for cleaning those put some on a clean rag and carefully clean off the throttle body being careful not to move the throttle position sensor as you will have to have it recalibrated if it moves too much out of position etc.

matts6887

also'; how many miles? have u done spark plugs?

ukrkoz

O2 sensor, aka air/fuel sensor, would have thrown code.
High RPM points towards air leak somewhere.
You need to do air leak check. Plenty of vids how to online.

Audiqv8

You will need a code reader in order to capture live data. Even though there are no codes it only means that the event has not occurred enough to trigger a check engine light or code. An example would be misfire. The ECU will only trigger a code for a misfire once a certain number of misfire has occurred. The RPM 1000 is high if this is what you're getting after the engine has warm up this could explain the lousy gas mileage. AFR sensors are expensive so rather than throw parts at it you need to determine what is the problem or find a Mechanic that you can trust.