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Genchi Genbutsu
Genchi Genbutsu, Toyota Master Technician
Category: Toyota
Satisfied Customers: 4394
Experience:  Toyota Certified Master Diagnostic Technician, ASE Master Technician with L1 Advanced Engine
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A 2000 r runner , engine light on and stalling/backfiring..p0171..lean

Customer Question

i have a 2000 r runner , engine light on and stalling/backfiring when sarting off cold. when warm still not 100%. code p0171 lean mix bank 1...trying to find vac leak with no luck....recommendations?
Submitted: 6 years ago.
Category: Toyota
Expert:  Genchi Genbutsu replied 6 years ago.

Genchi Genbutsu :

The P0171 code is for a Lean condition which is why I suspect that you are looking for a vacuum leak. What tests have you performed and what parts have you replaced?

Expert:  Genchi Genbutsu replied 6 years ago.

The P0171 code is for a Lean condition which is why I suspect that you are looking for a vacuum leak. What tests have you performed and what parts have you replaced?

 


Please reply back.

 

Genchi

 

Customer: replied 6 years ago.

I already know the code and what it stands for. I had this in my original question. I have replaced fuel filter and o2 sensor in front of catalytic. I had toyota and a mechanis say it sounds like a vac leak on the passenger side / bank 1. i am looking for help on identifying (location) of leak.

 

Expert:  Genchi Genbutsu replied 6 years ago.

Have you checked the MAF sensor for debris on the wires yet?

 

Genchi

 

Customer: replied 6 years ago.

yes, did not find anything

 

 

 

Expert:  Genchi Genbutsu replied 6 years ago.

With the engine running, have you tried spaying carb cleaner in and around the intake area?

 

Genchi

 

Customer: replied 6 years ago.
no, but problem mainly happens when cold. once car warms up it gets a lot better but not 100% at full throttle
Expert:  Genchi Genbutsu replied 6 years ago.

That will be the next item to check. What you will want to do is when it is cold, use some carb cleaner (anything spay flammable that will not damage your 4Runner) and direct it toward each area of the intake and listen for any changes in the way it idles. If it has a vacuum leak, it will suck in the spray and idle up higher. That will give you and idea of where the leak is occurring and then you can tear it down to inspect.

 

We don't have many of these issues but when the P0171 is present, most often it is the MAF sensor. I know you checked it and found it good.

 

Genchi

 

Expert:  Genchi Genbutsu replied 6 years ago.

Do you still need help?

 

 

Customer: replied 6 years ago.
it idles ok. it is when i put it in drive and start driving is when in stalls and back fires. i can put the pedal to the floor and it we seem like it is starved and wants to die. i have to let off step on it, let off step on it and it will finally begin accelerating.
Expert:  Genchi Genbutsu replied 6 years ago.

This sounds just like a MAF problem. In addition to the check listed above, I would replace the MAF, clear the code and retest drive it. It will probably make one heck of a difference. Please only use OEM Toyota MAF sensor.

 

Genchi

 

Customer: replied 6 years ago.

Thanks i willtry but do you think it might be the rear o2 sensor (behind catalytic)?

Expert:  Genchi Genbutsu replied 6 years ago.

No, please do not waste you hard earned money on replacing the O2 sensor, it will not fix this issue.

 

Genchi

 

Genchi Genbutsu and 6 other Toyota Specialists are ready to help you
Customer: replied 6 years ago.
thank you
Expert:  Genchi Genbutsu replied 6 years ago.

My pleasure.