Hey my friend has a 95 5spd Max with I/Y/E. It has 115K on it. Well he threw a code and diagnosed it. His MAF is dead. We found one at a junk yard for $170 (dealer wants $500). So we're gonna put it in later next week. His car now runs, but runs rough, and can't handle high RPM. Well that's not the point. He told me today that now his car "blows blue smoke" I told him not to worry about too much until we get the MAF fixed. The MAF might not be the only code he's throwing, but have you ever heard of this blue smoke on a Maxima? Anything else I should look into?

Thanks man, you rule!

I've never asked you for a question because most of the time I can hang on my own, but unfortunately I haven't seen/driven the car since this blue smoke thing came up, I've just heard his explanation of the problem.

 

Blue smoke in the exhaust means only one thing: burning engine oil. I can't think of any connection between a bad Mass Air Flow Sensor and burning oil.

Engine oil is burned if the piston rings are worn, the valve stem seals are broken, somebody put oil in the fuel tank, or the crankcase is overfilled. A blown head gasket can allow coolant to get into the crankcase. The water sinks to the bottom, the oil floats on the water, and the crankshaft splashes into the abnormally high level of oil. The splashing causes the cylinder walls to be drenched with oil instead of the desirable thin film, and it burns. The splashing also causes the blowby which passes through the Positive Crankcase Ventilation valve to be more oily than normal.

This sounds like a potentially serious problem. I suggest you start by pulling the spark plugs and seeing if any (or all) are oil-fouled. Then figure out where the oil is coming from. The rough running might be a symptom of oil-fouled plugs.

Now and then you hear the strangest stories. One fellow decided to replace the lube in his 5-speed transmission. He drained the tranny and carefully poured the four quarts of new gear lube into his engine! The result was predictable. He drove the car for 100 miles with clouds of blue smoke coming from the tailpipe. The gearbox "died" from lubrication failure and the Catalytic Converter was almost plugged with oil residue. Not a pretty picture.

 

Here's a scenario with an indirect connection. Suppose the air cleaner element had been removed... or maybe it just disintegrated due to age, exposure to water, etc. Without an air cleaner the engine could draw in unfiltered air and maybe a whole lot of foreign matter including abrasives such as sand. Consequences:
- accelerated wear in the cylinders leading to burning oil
- contamination of the Mass Air Flow Sensor triggering the Service Engine Soon light

Visualize the engine's air intake tract. What is the first thing the air stream reaches, after the filter? It is the MAFS.

 

Dude, Daniel already gave you the info you needed, but I just wanted to say when you see blue smoke coming from the exhaust, it's not something you would want from any car you own and the more you drive, the worse it gets. The damage could be done and your friend may have to start using heavier oil to keep from burning it so fast.