Q: Q: Reving

asked by on

How come when the truck is in park or neutral and I tap the gas it will rev up to 3000 rpm and then back down slow, but it doesn’t do it in reverse or drive

When the car is in gear, the load on the engine is sufficient to prevent the malfunction. If the engine idle speed on your vehicle is controlled by an idle control valve (ICV), that ICV valve can fail or a faulty or blown fuse in other electronically controlled systems can cause the IAC motor to malfunction, leading to a higher than normal engine idle speed. Failures in the ICV valve itself are often due to excessive carbon buildup in the intake manifold. Other possible causes of the excursion in RPM you are describing include vacuum leaks, a malfunctioning throttle and, rarely, a PCM/ECM malfunction. With regard to vacuum leaks, on a fuel injected engine a vacuum leak will cause high engine idle as the engine’s oxygen sensor detect the extra oxygen entering the engine through the vacuum leak. The newly lean (too much air relative to fuel) status will result in the engine’s computer pumping in additional fuel, resulting in an abnormally high idle. A malfunctioning throttle system can cause both a high idle as well as an engine stall. A dirty air intake or cracked air intake tube is often the culprit. If you desire that this high idle problem be diagnosed by a certified Mechanic, dispatched by YourMechanic right to your location, please request an engine idle speed diagnostic - high idle and the responding certified mechanic will get this taken care of for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: The blower motor does not turn on and the blower resistor starts smoking

A seized blower motor can be the cause. If the motor is seized and is drawing too much current, it can damage or burn the resistor as well as other electrical components in the heating/air conditioning system. Have a certified...

Q: Car is showing the following codes: P0700, P0734, P0735 & P1775. Transmission is only 1 year old.

Hello. The key code here is likely the P1775 code, which means the solenoid for invoking torque converter clutch lockup is latched (or engaged). If this solenoid does not unlatch, or release the lockup clutch, the transmission controller gets "speed...

Q: Q: Exhaust manifold

You may have broken bolts or studs in the engine head that would cause an exhaust leak. You may need to remove the manifold and extract the broken off bolts from the cylinder head by drilling them out and using...

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...