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Car hesitates accelerating from stop but only after driving for a while

I’ve got a 2013 Ford Fiesta with about 33,000 miles on it. I think there’s a problem in the fuel system. I took it to a mechanic, but he could not reproduce the issue so he did not fix it.

The car tends to hesitate when I accelerate from a dead stop. It sort of bucks, shakes, and hesitates a little. I think I hear some sort of knocking and scraping sounds from below, as if there is something down there that is hanging too low and hitting the ground.

I think that the mechanic could not reproduce this because the car was not “tired”. What I mean is that the mechanic is a mile down the road and my sister took the car there in the morning. The car usually works very well under those conditions.

However, I have a long commute through a lot of stop and go traffic. I drive about 32 miles each way every day. It starts to get worse when I get close to work in the morning, but is pretty consistently bad in the evening when I get home. The spark plugs were replaced recently, and the mechanic said he didn’t see anything wrong with the fuel injectors. But I take that with a grain of salt.

Any idea why this is happening and only seems to happen after the car has been running for a while?

A plugged catalytic converter is a possibility along with bad fuel.I suggest you fill the tank with fresh gas and see how it goes.

Ford has extended the warranty on the dual clutch automatic transmission to 7 year/100,000 for a problem with clutch shudder.

Don’t delay on having this checked out, if your vehicle was put into service before 09-19-2012 this warranty extension has expired.

This has been going on through several tanks of gas though so it can’t be bad gas.

I have no clue when the car was put into service. How could I find that?

The dealer can check the records for the in-service date.
Check the build date on the manufactures label in the drivers door jam, if manufactured after today’s date the vehicle is less than 7 years old.

I forgot to mention that sometimes there is a little shaking when coasting. As in, I’m sitting in heavy traffic at a stop light and the light turns green. Then I coast for a little bit before accelerating.

You said mechanic can not reproduce problem because does not act up till it is driven far enough when he see’s it wait untill you get home from work then take it to him while it is still acting up so he can see the problem.