When I start the car, the RPMs ramp to max. I changed the ECM, throttle body, throttle position sensor, and cam position sensor, but it still does the same thing.
Hi there. If the throttle body is fully closing then this is either caused by an electrical short or a vacuum leak. If the throttle body is not fully closing then the throttle cable may be binding. I would suspect a vacuum leak. This may be caused by a loss or broken vacuum hose, a bad gasket or possibly an EGR valve that is stuck open. I typically run the engine and listen for any noses making a hissing sound which indicates a leak. Once those are eliminated, if the problem occurs I do a smoke test to see if I can find the leak. It can also be one of the other sensors, but that is not as common. If you were looking to have this repaired, consider YourMechanic, as a certified mechanic can come to your office to diagnose why you are having abnormally high RPMs.
Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing