Zookeeper7

Hi I drive a 2006 RX350 and my check engine light and VSC light came on a while ago the car losses power when excelerating at times and when I put my foot down it comes good,I have taken it to the mechanics several times, when the codes were read it comes up missfire in several different cylinders they have changed the spark plugs, coils and plugs that go to the coils and the lights always come back on, I was thinking that it might be the oxygen sensor.
Is it possible that the O2 sensor is faulty without coming up with a faulty o2 sensor code?

Mesquite77

VSC triggers because of CEL, ignore the VSC.

1) When they changed the plugs, did they do a compression test? If not, then that could at least rule out something bad.

2) Can you please post a closed loop fuel trim reading.

3) Smoke test for vacuum leak?

Not to scare you, but a bad cylinder will be less noticeable at higher throttle than idle, but the fuel trims and compression test can help rule things out. Of course, simple vacuum leaks also high on suspect list.

uksparky

light comes back on ..what code do you get
Check your gas cap for sealing, check the o ring

Margate330

We need the codes! lol

Generic engine misfire codes don't tell a whole lot but it can in combination with ther codes and we can't go by what the mechanic said aka 3rd party info.
To have any chance of going further DIY with this you will need to buy your own scanner that is capable of displaying live data.

Good ideas already posted just like to add could also be a weak fuel pump too if fuel trims swing wildly in the negative direction like -20 to -40 during acceleration and there would be a code for it if it swings too far out of range and easily seen on a scanner.

With your own scanner you can clear the codes and give better description of what codes there are and when they happen such as engine is cold, under acceleration, etc.

mandyfig

My Scangage is now a permanent fixture in my RX. I clear CEL's on the fly.

spinellib

Ha!
Whatever it takes.

mandyfig

I note down the code so I can do research on them, on the ones that are recurring and persistent. Then I find a solution to it so it does not re-appear. The onesies, I just clear them, on the fly. Thanks for the scan gage.