Ok so I've got my 95 318ti with a bad idle sometimes, thought it was the MAF sensor and replaced it, car runs better but everyonce in a while it almost dies at the stoplight, and the check engine light comes on under heavy acceleration sometimes. Did the, key in pos2 and stop gas 5times and got code 1222, Lambda Control 1, what the heck is this and how do I fix it??
Well that could be the cause of the rough idle. An 02 sensor measures the air/fuel ratio in the exhaust gases and tells the engine computer if it's running lean or rich. This in turn determines the amount of fuel that your engine puts into the combustion chamber trying to maintain the perfect air to fuel ratio for gasoline burning in oxygen. If the 02 sensor fails then the engine computer doesn't know how much fuel to burn in order to maintain that ratio and just does whatever it wants. Thing is the amount of fuel to burn to maintain that ratio changes with numerous different conditions, how hot the engine is, the ambient temperature, how hard you're hitting the gas that sort of thing. Rough idle can also be due to a dirty idle control valve, malfunctioning maf, vacuum leaks a lot of stuff really
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