Poor fuel mileage after a tune up was done?

2017 HYUNDAI ELANTRA
46,000 MILES • 2.0L • 4 CYL • 2WD • AUTOMATIC
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MYRA SANDOVAL
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Before I had a tune up, I got 32 miles a gallon highway. After the tune up I'm only getting 24 miles a gallon highway. What can the problem be?
Jun 26, 2023 at 10:46 AM
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STRAILER
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It sounds like they installed the wrong spark plugs or the gap is off. Here is a guide to help you do the job correctly and instructions for your car in the images below.

https://www.2carpros.com/articles/how-to-change-spark-plugs

Spark plug:
Type ELR9IQP9+
Gap 0.8 - 0.9 mm (0.0314 - 0.0354 in.)

Check out the images (below). Please let us know if you need anything else to get the problem fixed.
Jun 26, 2023 at 6:11 PM