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Chris (aka - Moose)
Chris (aka - Moose), Technician
Category: Lexus
Satisfied Customers: 47613
Experience:  16 years of experience
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Lexus RX 300 Bank 2 misfiring on all cylinders with Code P

Customer Question

Lexus RX 300 Bank 2 misfiring on all cylinders with Code P0171
Submitted: 2 years ago.
Category: Lexus
Customer: replied 2 years ago.
I have replaced both the front O2 sensors and confirmed they have the correct resistance (1.2 ohms)
The bank 2, O2 sensor was bad and had no resistance and the car was driven for a few days in this condition
Expert:  Chris (aka - Moose) replied 2 years ago.
Is this an intermittent miss or permanent? Your code is for bank one running lean, o there is an air fuel ratio issue from fuel pressure concerns or a vacuum leak. This can effect the other bank from making it run to rich or lean as the computer tries to address this. Have you done any testing to try and resolve the lean code? You want a excellent 5 star answer & I would like to be rated the same for providing it. Consider I don't know your skill level & I can't see, smell, hear, or touch the vehicle. It may take a few back and forth replies. Try your best to respond with good detail so I can do the same. I normally log in at 3pm and work late. A rating is required. Your rating me, what I type. I am not an employee of this website, nor have control over the fees or the time it took to get a response. If you rate negative or not at all you still paid, but I get nothing. I want you pleased with me and my efforts, so let me know if your experience here has come up short.Thanks Chris
Customer: replied 2 years ago.
Sorry I meant bank 1.' o there is ' ? please clarify I have checked compression on cyl 1 and looks good. As all 3 cyls seem to have the problem presume (unlikely) it is not going to be spark or compression related - correct? Apart from that and changing the O2 sensors I have not done any other troubleshooting, as thought was the 02 sensor causing issue. Originally I just had P0171 and no other code.
Expert:  Chris (aka - Moose) replied 2 years ago.
You are correct spark issues would rarely effect a complete head, though timing can, but you said the compression is good. Can you check for vacuum leaks?
Customer: replied 2 years ago.
Yes I have an engine vacuum and fuel pump tester - but never used it before
Expert:  Chris (aka - Moose) replied 2 years ago.
To check for vacuum leaks, you start the engine cold, and spray short bursts of flammable brake cleaner around the intake and hoses anything under vacuum. If there is a leak then the engine will rev up when the leak is sprayed.

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