****EDIT***Fixed***

It was the oil control solenoids. hope this helps someone else. sorry i forgot to update sooner

Good morning fellow Lexus people,

I really hope you can help point me in the right direction. My 2000 RX300 with about 220k miles starting misfiring at idle over the weekend. I was at work and was able to make it home (mostly highway which the car seemed ok). The codes I pulled were:

P0300, P0301, P0303, P0305 - Multiple misfires/ bank 1 misfiring

P0171 - bank 1 lean
P0128 - Engine coolant code
P1130 - B1S1 A/F ratio sensor (hopefully)
P1346 - VVT/ Timing code

I did a bunch of research here (thank you) and replaced the bank 1 sensor 1 air/ fuel ratio sensor. Well, almost, I unplugged the sensor but was unable to break the sensor loose in my driveway. I drove it a few miles to Pep Boys (with the AF sensor unplugged) and the only code I got was for the a/f sensor heater circuit and nothing else. At this point I thought changing the sensor would definitely fix all the problems after only getting the heater circuit code. The guys at PB were able to get the new sensor in and everything was fine for about 5 miles (test driving and home).

I drove the car about 50 miles to work that afternoon and everything seemed fine. Then when I was on my way home from work the night after changing the AF sensor all the same problems came back.

Where do I go from here? Thank you

 

Welcome to ClubLexus.

My hunch is the issue is with vvti bank 1. This would be the firewall side. Good luck taking it out, but I would clean/replace filters and O rings and bench test it.

To do precise debug, you need some live data or scope.

With that many miles on the odd, I hope you are uptodate with plug replacement and timing belt.

Salim
ps: check out the CarCareNut videos. I faintly recall Abd discussing bank1 issues.

 

Thank you for the rapid response. I know the timing belt was done with the water pump at around 100k but I don't know if the plugs were ever done.
I don't think i'm going to be in a position to remove the valve covers in my driveway or afford to have that done at the moment.

Is there a possibility that with livedata one faulty part can be pinpointed or the valve covers have to be removed no matter what at this point? Thanks again I really appreciate your help

any other diagnostic steps I may be missing?

 

Also thank you for the welcome and I'll look into CarCareNut now

 

There is no need to open the valve cover.

Timing issues when related only one bank are typically influenced by that bank's timing advance mechanism. Although the timing advance mechanism should not become active at idle.

I would suggest clear codes and observe again. If the code is thrown after trekking above 3k rpm then the cam advance becomes highly suspicious.

Salim