My car will start properly, but once driving it won’t go more than 25 mph. Once it reaches 20-25 mph, the gas will stop flowing and I can't accelerate until it goes back below 20 mph. I thought the problem might be the fuel filter, so I replaced it, but that was not the solution. Can you help me by giving a diagnosis and what will solve this?
There are several possibilities that can cause an engine to fall on its face when it hits certain RPM ranges. It could be a fuel delivery issue, air issue, or an input sensor such as a crankshaft sensor or mass airflow sensor setting injection timing incorrectly.
Fault codes need to be read out first to see what obvious issues might be present and those items corrected. Vacuum leaks and unmetered air leaks need to be sought out as this can cause lean misfiring and issues on acceleration.
Crankshaft sensor signal needs to be looked at as well, if the signal is not clean, it will cause issues at higher RPM's and cause ignition and injection to cease. You may want to enlist the help of a mechanic, such as one from YourMechanic, who will have the equipment and expertise to diagnose and correct this acceleration concern.
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