Tasked with keeping track of how much air flows into the engine, the mass airflow (MAF) sensor plays a key role in determining how much air needs to be in the combustion chamber. The MAF communicates with the engine control module (ECM), and if it sends misread air amounts, the ECM will adjust how much fuel it allows into the combustion chamber. Mike’s Auto Service & Repair explains that this can throw the air and fuel mixture off and, as a consequence, you’ll notice the list of things below.
1. Lean or Rich Fuel Mixture
If the MAF is not reading the air influx correctly, the ECM may reduce the amount of fuel in the combustion chamber and create a lean fuel mixture. The ECM may also increase the amount of fuel in the combustion chamber and create a rich fuel mixture. Your vehicle will have a hard time idling on either a lean or rich fuel mixture, and it will sputter and might even stall.
2. Difficulty Starting Your Car
Another sign that the fuel mixture is off is problems starting your automobile. A lean fuel mixture means that there isn’t enough fuel in the combustion chamber for the spark plugs to ignite. A rich fuel mixture could be flooding the engine with too much diesel fuel or gasoline. Either condition will make it hard to get your automobile started, especially on a cold morning.
3. Engine Stalls After Starting or When Idling
Because the air and fuel mixture isn’t balanced correctly due to the faulty mass airflow sensor, your engine may stall very quickly after you finally get it started. It can also stall while you are idling, as discussed above. This can be attributed to the lean or rich fuel mixture being caused by the ECM because of the faulty MAF.
4. Engine Hesitation and Dragging
If the mass airflow numbers indicate there is less air in the engine than there actually is, the ECM will reduce the amount of gasoline flowing into the combustion chamber. This will cause your engine to hesitate and drag, especially if it is under stress. Things that can cause additional stress on your engine include towing and driving up a steep hill.
5. Engine Hesitation and Jerking
Too much fuel can make your engine hesitate because it is being flooded. It can also make your acceleration jerky. As you are driving along, if there is too much fuel in the engine, your engine may surge, which means it picks up speed even though you didn’t increase your foot pressure on the accelerator.
6. Engine Hiccups
Finally, an air and fuel imbalance caused by a mass airflow sensor that is going bad can also make your engine hiccup. It will stutter and hiccup as you drive along and, depending on the air and fuel imbalance, it might even stall as you slow down and stop.