iamdk72986

Hi guys. I have a 01 RX300 AWD with 98k miles. Bought the car with 76k about 3-4 years ago. My question is this: my long term fuel trim for bank 2 is at about 20% while bank 1 is within the acceptable range. My exhaust system is completely free of any leaks, had the a/f sensor on bank 2 replaced about a year ago when I was diagnosing a knock sensor problem, and replaced the fuel injector in cylinder #2 last year as well. Spark plugs were changed last year with NGK Iridium IX's. What confuses me is that the car is not throwing any CEL's. My CEL does work as it should. I'm pretty mechanically inclined but this is one thing that I can't figure out. Perhaps it's carbon buildup on the injectors on bank 2? The reason I've looked into this is because the car feels quite sluggish, especially compared to another RX I've driven. Or maybe I'm just too used to the speed and pickup of my 3000GT VR4 lol. Thanks in advance.

Daniel

sktn77a

iTrader: (2)

Pardon my ignorance, but what is "fuel trim"?

iamdk72986

Fuel trim works like this:

Fuel injectors are set to open for a set fraction of a second by the ECU to deliver fuel into the combustion chamber. The air/fuel sensors in each bank measures the the gases burnt to make sure it's at an ideal ratio of 14.7:1. When the A/F sensor reads that it's either too lean or too rich, the ECU will compensate for it by opening the injector slightly longer than originally set time for a lean condition, or by closing it slightly earlier for a rich condition. That compensation is called fuel trim. It is measured in percentage. There's short term fuel trim and long term fuel trim.
Short term fuel trim is the adjustment of fuel on-the-fly while long term is the adjustment of fuel over an extended period of time. Long term fuel trim within single digit percentage is acceptable. Once it hit's double digit percentage, that shows that there is a problem with any component that is responsible for fuel delivery. It could be a faulty A/F sensor, an intake leak, a clogged/faulty injector, etc...
Hopefully I explained it in a way you can comprehend it lol. Good thing I didn't go into teaching as I'd probably confuse the hell out of the students.

Daniel

sktn77a

iTrader: (2)

Never too old to learn something new!