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Q: Car is vibrating when accelerating - 2003 Chevrolet Trailblazer

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When I press my gas from a stop it feels like I'm pressing on air like my car isn't getting power but while I'm pressing it the car is vibrating after a few seconds it stops then takes off like normal and it will continue doing this every few minutes or so I also lost my gas cap and left it off for about a month just got a new one 2 days ago don't know if that had anything to do with it just got my oil changed also and transmission fluid is full.

My car has 1128933 miles.
My car has an automatic transmission.

Hi there. There are several possibilities for the vibration and lack of power upon vehicle acceleration. The missing fuel cap should not affect drivability. Assuming the Check Engine Light has been on for the missing fuel cap, this leads me to believe the ECM (engine control module) may be recognizing the fault upon acceleration.

If the Check Engine Light flashes when the vibration is felt, this would indicate an engine misfire. This may be the result of a [faulty/worn spark plug](https://www.yourmechanic.com/services/spark-plugs-replacement or a faulty ignition coil. It could be also be a low fuel pressure situation caused by a faulty fuel pump or a faulty fuel pressure regulator. Accessing the ECM/computer for codes may help identify the area of concern.

I recommend having your vehicle’s vibration and lack of power be diagnosed and repaired by certified technician, such as one from YourMechanic.

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