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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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1996 Toyota Camry: the drive cycle for evap per expert and it..NOX

Resolved Question:

1996 Toyota Camry 4 cylinder.
Just completed the drive cycle for evap per expert and it worked.
I failed NOX but all other readings fine. I failed by 100PPM car has 135K on it but it is a new engine 3 mos. Is it worth attempting the upper O2sensor? My live data OBDII does show it fluctuates. I did buy a can of fuel cleaner and put it in after the test.
All readiness tests have passed including the EGR test.
Submitted: 6 years ago.
Category: Toyota
Expert:  Genchi Genbutsu replied 6 years ago.

Genchi Genbutsu :

You said that you passed the EGR but failed the NOX readings?

Customer :

Yes. The EGR computer self test. I had to replace the VSV and did the checkout of the EGR system per alldata.

Genchi Genbutsu :

Is it worth attempting the upper O2sensor? Yes it would be but also it would be worth to clean out the upper intake with like Seafoam or Toyota's Top Engine Cleaning kit.

Customer :

I cleaned the intake prior to installation on the rebuilt motor. How often does o2sensor effect NOX but not other emissions

Genchi Genbutsu :

It helps with fuel control but usually Nox is due to high combustion temperatures. Things like plugs, carbon buildup, egr flow all can contribute to high Nox readings.

Customer :

Thats what i thought. So replacing 02sensor expensive. may not help at all. Should I put seafoam through the egr port on intake manifold. engine is too new for carbon buildup. how about retarding timing a few degrees?

Genchi Genbutsu :

Should I put seafoam through the egr port on intake manifold Yes/ Basically you will want to make sure that you are getting as much EGR flow as possible. how about retarding timing a few degrees? You can but only take it as far as is limited or needed but not too far as to effect other items.

Customer :

Understand. Not much I didn't know but I will accept answers.

Customer :

I won't but o2 sensor for now

Genchi Genbutsu :

My pleasure.

Customer :

buy not but

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