My car has a manual transmission. It has gone around 120,000 miles. After driving it for a short time, it would start revving over 2700 RPM when it idles. The revving happens at higher RPMs. If I turn the car off and start it up again, the issue would disappear for some time. The dashboard doesn't show any lights on. Do you have any idea what could be causing this?
Hello. When this car idles high like this it is because there is a vacuum leak. A vacuum leak will allow too much air to enter the engine causing it to idle too high. The most common place is at the intake manifold gasket. It can also leak from one of the hoses or from a bad EGR valve. I usually do a smoke test first to see if it shows the leak. I will also spray throttle body cleaner around the possible leakage areas to see if the idle changes. If it does, then there is a leak. If you plan on having this repaired, consider YourMechanic, as a certified mechanic can come to your home or office to diagnose your car's high engine idle.
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