1998 Nissan Altima, Trouble code P0171, Ongoing problem
As before the P0171 code keeps popping up, I changed the front Oxygen Sensor, Air Mass Mater, fuel filter & finally found the PCV valve, when I changed the PCV Valve the car ran much better and the code didn't come back up, but after a couple of days the car started running the same, poor rough idle, poor gas milage & and a gas/exhaust smell in the car. Could the PCV valve have clooged up so fast, possibly because of gunk in the line or where the valve plugs into?
how often do you change your Oil ? is there any Sludge in the Engine ? you may be looking at a lengthy overhaul of your engine internals if there is a Sludge buildup
There should not be any sludge in the engine, I or my son changes the oil once every 3 months and there is usually not 3,000 miles on it by that time, this engine was replaced about three years age because the timing chain broke and trashed the original engine, the replacement engine was used, about 68,000 miles on it, when installed, the oil was changed @ 1,000 miles then at a maxium of 3,000 there after, can't understand if the engine is sludged up, I'll take the PCV valve out again tonight to see if it'e clogged up, if it is, I guess there's a problem.
look vor vacuum leaks or intake or exhaust leaks. p0171 lean means theres too much oxygen and most likely is pulling air in at the intake manifold gasket or if you're smelling it inside car could be exhaust leak which may be sucking air in there causing the oxygen sensor to read too much oxygen and setting codes. so inspect intake and exhust for leaks.
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