2005 Volvo XC90 smoking periodically

IT SOUNDS LIKE THE ENGINE MAY BE RUNNING RICH. THE ENGINE HAS FOUR OXYGEN SENSORS, WHICH SENSOR WAS REPLACED AND WHY? WAS IT RESPONDING SLOW? WAS IT NOT RESPONDING AT ALL? WHAT ARE THE READINGS ON THE OTHER SENSORS? ARE THERE ANY AIR LEAKS IN THE SYSTEM? WHAT WAS THE READING FROM THE MASS AIR FLOW SENSOR? WHAT IS THE THROTTLE ANGLE? ETC. THERE ARE A LOT OF FACTORS IN TRYING TO FIX THIS KIND OF CONDITION. GOING TO AN INDEPENDENT REPAIR SHOP IS RISKY BECAUSE THEY MAY NOT HAVE THE PROPER SYSTEM TO DIAGNOSE OR MAY NOT KNOW WHAT THE SPECS ARE WHEN LOOKING AT THE DIFFERENT READINGS. MY SUGGESTION IS FOR YOU TO TAKE THE VEHICLE INTO A VOLVO DEALER TO GET A PROPER DIAGNOSIS. THESE ARE THE HARDEST CONDITIONS TO FIX, PRIMARILY BECAUSE THERE ARE SEVERAL COMPONENTS THAT CAN BE CAUSING THE SAME CONDITION. THE LAST THING YOU WANT TO DO IS START SPENDING MONEY ON REPLACING COMPONENTS THAT MAY NOT BE NEEDED.

DO YOU KNOW WHAT THE KGH READING IS FOR MASS AIR FLOW SENSOR? JUST TO LET YOU, SOMETIMES THE SYSTEM MAY POST A MASS AIR FLOW SENSOR FAULT CODE, BUT IT DOESNT NECESSARILY MEAN THAT THE SENSOR HAS FAILED.

For Mass Air Flow sensor codes you should be looking for a dirty throttle body. Root cause for a dirty thottle body is a plugged up PCV system. If the PCV system is really bad they cause the turbos to leak internally and could explain why your vehicle is smoking. To properly diagnose the PCV system you need a special gage you insert in the oil dipstick tube.

The values are in the negative side so this indicates the PCV is not plugged up. The lower the value the better. If at 0 or on the plus side, it is restricted. When restricted you need to replace the oil trap box and clean out the banjo hose.

Here I am cleaning one out.

Here is a diagram of the oil trap box.

Here is a basic explanation on the PCV system.

CRANKCASE VENTILATION

Crankcase gases are removed from the cylinder block (and cylinder head to an extent) to an oil trap (1) where oil is separated from the crankcase gases and returned to the oil sump. The hose to the cylinder head equalizes differences in pressure between the upper and lower parts of the engine.

When there is little load on the engine or when it is idling there is no under-pressure in the fresh air hose and only a small quantity of crankcase gases are formed. Because of this a vacuum hose (7), to lead crankcase gases directly to the intake manifold at low loads, goes from the heating nipple to a calibrated intake downstream of the throttle.

The heating nipple is calibrated to provide a controlled flow of crankcase gases. Power to the PTC type nipple is supplied by the engine management system main relay and prevents water vapor in the crankcase gases from freezing in the fresh air intake hose at low temperatures.

The PTC nipple temperature stabilizes at approximately 80 °C (176 °F) as soon as the engine is started.

So before you spend any more money you should have it properly diagnose.

Hope this info helps and if you have any other questions, let me know.

BEFORE DOING A THROTTLE SERVICE, INSPECT THE THROTTLE ANGLE AND SEE WHERE IT READS. AIR MASS METER CODES DON'T NECESSARILY MEAN THE PCV IS PLUGGED. WHEN HAVING AIR MASS METER CODES, THE VERY FIRST THING THAT YOU NEED TO DO IS CHECK THE "KGH" READING AND GO FROM THERE. IT MAY BE AN AIR LEAK IN THE INTAKE SYSTEM FROM A HOSE OR A GASKET, THESE CONDITIONS WILL CHANGE THE READINGS FROM THE MASS AIR FLOW SENSOR. IT MAY END UP BEING A PLUGGED PCV OR A DIRTY THROTTLE, BUT YOU MUST FIRST CONDUCT THE NECESSARY STEPS TO GET THERE.