Q: When giving gas car will misfire and shake badly

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Some days when I go to leave in the morning crank the car and idles with no problem runs smooth. When I pull out, the is a very small incline and acceleration to speed up the car misses badly and will barely make the hill and continue to shake. No lights come on for a warning. I have driven on to the shop only to be able to reach 15mph max and had it towed 3 times. Each time when getting to the shop it runs perfect and will continue running good a day or two and do it again. They have changed fuel filter, fuel injectors (which it showed on the test once), catalytic converter, and a couple of sensors and can't locate the problem. Please help if you can. Thanks

Unfortunately, that seems to always be the way things go. The problems act up when not at the shop and then vanish when the mechanic is looking at it. From what you describe, this may be a sign of a dirty or failing mass airflow sensor. The mass airflow sensor is a unit in the intake system that monitors air intake as it is mixed with fuel prior to being injected into the motor. When this fails, this can cause an imbalanced air/fuel load to be supplied to the motor which results in an over fueling or under fueling situation depending on the conditions. This is what causes the hesitation or loss of power you describe. This can also cause the engine to struggle to idle for the same reason. To avoid any unnecessary repairs, I would suggest having a professional from YourMechanic come to your home to diagnose the shaking condition firsthand and service your mass airflow sensor as necessary.

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