Q: Mileage is getting progressively worse

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I recently had the plugs, plug wires and timing belt replaced. My mileage was 20 mpg before the work and has dropped to less than 10 mpg. There is a significant loss of power and the engine bogs down and runs rough.

My car has 250000 miles.
My car has an automatic transmission.

Hi there. This can be caused by a number of things. If it occurred right after the work was done then you may want to have it double checked. They may have used poor quality wires or the wrong spark plugs.

It is also possible that you have a leaking fuel pressure regulator or a fuel injector as they will also cause this.

If the engine runs smooth but just lacks power and MPG then you may also be looking at a bad catalytic converter. If the vehicle was running bad before the tune-up then this is possible. A back pressure test would need to be performed to verify if it is bad.

If you want to have this done, consider YourMechanic, as a certified mechanic can come to your home or office to diagnose your decreasing gas mileage and repair it as necessary.

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