Passed emissions after NOX fail, P0171 CODE

[adee01]

Thanks to all the fellow DIYers, I post this on a positive note after clearing the emissions on my Toyota Camry 2002 V4, 112 k miles after 2 failed attempts. The accelaration of the car is also MUCH better.

So I failed NOX emissions..NOX was above 5000 when the limit is 1500. CEL has been on for more than 1 year with P0171 code....acceleration of the car especially going uphill was also pathetic. Whenever mentioned CEL and acceleration to mechanic, he just asked to put a higher octane gas and quit worrying or be ready to spend big $$$. (in CO..85 octane is the lowest and 87 is mid grade)

Mechanic checked vacuum leaks, catalytic converter, EGL valve opening and closing...all looked OK. Changed spark plugs, air filter, did regular tune up in the process but car still kept failing NOX.

Took to a emission specialist..he cleaned MAF and wow...the car passed the emissions, NOX down to 750. The other problem of acceleration also solved..car responds much better now.

CEL still came back on and specialist advising replacing MAF. I am not convinced...cleaned it 1 more time with CFC MAF cleaner and reset the codes. Will see if CEL comes back again.

Going through many forums, am planning to do seafoam treatment 150 miles before my next oil change.

Wondering why the hell cleaning MAF is not a recommended procedure in Toyota manual. Seems such an easy thing to do.....and I could have saved $, time, and quit spewing harmful gases much earlier.

[arabianobsession]

Welcome to TN!

^BTW, your car is an I4, not a V4.
Over time, the MAF will get dirty and many will fail, and that's in every car you find.

[Pilot0617]

Originally Posted by arabianobsession

Welcome to TN!

^BTW, your car is an I4, not a V4.
Over time, the MAF will get dirty and many will fail, and that's in every car you find.

[gdanaher]

Go to the parts store and get a couple bottles of RXP and run those through a couple tanks of gas. This stuff actually works to clean the carbon out of the top end and lower emissions.

[adee01]

Thanks for your comments....and suggestions. I am obviusly a newbie in this area and have to learn many things from the experts

[arabianobsession]

It's all good. Just remember this site is here to help you!!! And we're all willing to help as well