Greetings, I'm new to the forum, but not new to cars. We have a 2005 Lexus RX330 that we bought used with ~39,000 miles earlier this year. Great car. However the maintainance required light came on a few days ago.
Being a gear head in my spare time, I know my way around cars (my hobby is a 1971 Camaro that I swapped in late model EFI). I have an OBD-II scanner, so I scanned the Lexus and no trouble codes were set. I did notice some curious things on the real time data and wanted to bounce it off you guys to see if there's an issue here.
1.) TPS sensor is reading 16% at idle with throttle closed. In all the other cars I've scanned, it typically reads 0%. I did step on the accelerator and the TPS % does increase smoothly.
2.) The scanner is able to read two O2 sensors. Though I'm not sure if the vehicle only has two. In any event, both O2 sensors were very sluggish in their responses, basically hovering around 720 mV... changing by about 10 mV every second or so. Again, on my Camaro, the O2 sensor bounces around quickly around a centering voltage of ~450 mV. If this were the Camaro, I'd conclude that something is pegging the exhaust into the rich zone or the O2 sensors are bad. Not sure if this is normal for Lexus
3.) Long term fuel trim is ~10%. That seems like a lot for a factory tuned car. I'm able to tune my Camaro to within 5% without a dyno or anything. The fact that this Lexus is off by 10% (combined with the O2 sensor data) leads me to believe there's some issue with the fueling???
Thanks in advance for your help