Why Is My Car Revving In Park?

Modern cars are not like your dad’s or grandpa’s vehicles when they were your age. Back then all you needed was a screwdriver to adjust the idle. Today, car and truck engines are not so simple and there could be a variety of parts contributing to this problem.

To find out what is causing this problem, just continue to read our article. It has that information and more. Take a few minutes to see how this data can help you out of a sticky situation.

Why Is My Car Revving High On Its Own

If you noticed that your car’s engine is idling at higher speeds when in park or neutral, that is a sign that there is a problem under the hood. Most cars and trucks have a little screw that adjusts the idle speed. However, that little part may not be the source of your problem.

It is the first place to check though as adjusting that screw may be all you need to do. If it doesn’t solve your problem, then you need to check the following areas to see if they are causing this revving problem

1. Mass airflow sensor is dirty

This is a tricky device and its purpose is to monitor the airflow volume coming into the air intake as well as the throttle valve. That information is sent to the car’s computer which then regulates the amount of fuel so the correct air/fuel ratio is maintained.

When that little sensor gets dirty, the information it collects is corrupted and the device sends faulty information back to the computer. Which in turn creates a rich running engine. This means that the air/fuel ratio is off.

The good news is that all you have to do is clean this sensor and the problem should be solved.

2. The throttle body valve is sticky or dirty

This valve opens and closes when you press your foot down or release the pressure on the throttle. This valve’s opening and closing depend on the pressure given to the throttle. When it becomes dirty or sticky, then the valve does not operate at optimum levels.

There are two ways to solve this problem. You can use a cleaner designed to clean the throttle valve. But if that does not do it, then you are looking at replacing the part

3. Oxygen or O2 sensor has failed

This is one of the troubles with modern cars. There are so many parts that can fail, it is hard to determine the source. What this part does is monitor the emissions that go from your engine to your catalytic converter.

What makes this part fail and not do its job properly are the carbon deposits that can stick to the sensor. When it gets so dirty from these deposits, it cannot do a very good job and the data it receives is not what is actually happening in that part of the motor system.

Thus, the computer sends false information to other parts which then adds more fuel or air to the engine causing it to idle when you are not moving. An OBD2 scanner may be needed to see if this part is dirty and replacing it may be your only option.

4. Vacuum leak

As technology advanced, car makers found that using a vacuum system in your car’s engine provided better performance. However, since the vacuum system is comprised of rubber hoses.

These rubber hoses can get old, become brittle, crack or even break and when they do, the resulting leak wreaks havoc on your idling system. The trouble with these leaks is that they may not occur in obvious easy to see places or the hole is so small you cannot see it.

Tracking down the leak may take some time. When you find the leak, you will have to replace the broken or cracked hose. There are different methods to use, such as the smoke test, to help you find that failed hose.

5. EGR Valve failed or is plugged

EGR stands for Exhaust Gas Recirculation and it is a newer system designed by car makers so that their vehicles and motors would pass strict emission standards. All it does is recirculate the exhaust fumes back through the engine before it reaches your tailpipe and is sent into the open air.

The EGR valve also opens and closes when needed but like the O2 sensor, it can get dirtied by the carbon in the exhaust emissions. When this happens your idle will react and not function normally.

There is some good news. When this part fails it is not expensive to buy or replace. The trouble is finding it and getting access to the part so you can do just that.

Misc. parts and a better diagnosis

There are other parts that can go bad on you and cause this idling problem. To name a few, there is the Throttle Body Valve Position Sensor, a bad computer, or frayed or loose wires. All of these parts can contribute to this issue.

Investigating this problem can take some time if you are going from part to part to part. There is an easier way to handle the diagnosis. All you need to do is hook up an OBDII reader to your car’s computer system.

This reader can track down the failed part or problem much faster than investigating each part individually. The good news is that once the reader finds the source, most home mechanics can fix most of these problems with little effort and expense.

Some final words

Just because car engines have become more complicated does not mean that the problems are not easy to fix. You just have to do the right diagnostic work and see if the repair is within your skillset.

In the meantime, complicated car engines make us miss those good old days when all you needed was a simple screwdriver and a turn of a screw.

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