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Toyota Repair/failed AZ emissions


1994 Toyota 4wd pu 3.0 6 cyl fuel injected  manual 5spd trans  it sat inoperable for several  years before I bought it  I drained and cleaned gas tank, replaced fuel pump, timing belt, water pump, egr modulator. Before theae repairs it read code 71, now check engine light does not come on and it runs well but it failed AZ emissions
hydrocarbons (NC) in grams/mle  allowed 1.60  my reading  3.48
carbon monoxide (Co) (OC) in grams/mle  allowed 20.00  my reading  33.24
oxides of Nitrogen (NOX)  allowed 3.00  my reading 2.00
passed fuel cap, evaporative system, and pressure test

Hello, the HC reading is more than double the limit so this seems to be the main problem, once this is fixed the CO may also come down, high hydrocarbon emissions are due to incomplete combustion, usually caused by a misfire, leaking valves, low compression, have you tried anything yet to repair the problem? Does the engine idle smooth and have no loss of power?  

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Ted Ritter


I have more than 28 years experience as toyota technician, I will be able to answer most questions related to the Toyota product line up to the present year models,I am located in the US but welcome questions from other regions of the world. When asking a question please provide specific information: year,model, engine,transmission information. Provide as much information as possible including a brief repair history if possible. I have been a volunteer here for more ten years an have answered over 16,000 questions helping Toyota owners with their problems and save thousands of dollars without any compensation, some of my answers are published on many other websites including google and various automotive forums. DONATIONS ARE VERY MUCH APPRECIATED, IF YOU HAVE RECIEVED HELPFUL INFORMATION PLEASE MAKE A DONATION. AS OF TODAY (JULY 22, 2014) ALL REQUESTED GRAPHICS, ILLUSTRATIONS, DIAGRAMS, PHOTOS, WILL REQUIRE THE MINUMUM DONATION UP FRONT.


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