Oil in the intake indicates that oil is getting past the piston rings or valve seals and entering the combustion chamber. When it burns, it creates excess air in the mixture (because it's being treated as fuel, but it's not) throwing off the computer's calculations and leading to the lean codes. The MAF sensor might be reading correctly, but the overall mixture is still off because of the oil.
Here's what you should do:
1. DO NOT IGNORE THIS. Continuing to drive with oil in the intake can cause serious damage to your engine, including catalytic converter failure.
2. Don't just replace the MAF sensor yet. While a faulty MAF *could* contribute, it's likely a secondary issue or a result of the oil consumption. Replacing it without addressing the root cause is a waste of money.
3. Take your Windstar to a qualified mechanic for a proper diagnosis. They will need to inspect the engine for signs of excessive oil consumption, potentially needing to perform a compression test and/or a leak-down test to pinpoint where the oil is getting into the intake.
Possible causes of the oil consumption include:
* Worn piston rings: These allow oil to get past the pistons into the combustion chamber.
* Worn valve seals: These prevent oil from leaking past the valves.
* PCV (Positive Crankcase Ventilation) system failure: A malfunctioning PCV system can cause excessive crankcase pressure, forcing oil into the intake.
Getting the oil consumption issue fixed is paramount. Addressing the underlying problem will likely resolve the lean codes (P0171 and P0174) as well.
