We have been asked this question a lot – Why does my RPM go up and down while parked?
At a glance, an RPM fluctuation or your Revolution Per Minute fluctuating while parked can be a very frustrating experience. Moreover, it can be dangerous since your engine will end up stalling and running roughly. There may also be some damages to other vehicle components, which is never a good thing.
When you are parked, RPM fluctuations may happen because of some issues with certain components such as the idle air control valve, throttle position sensor, and even your fuel pump or fuel filter.
There are also instances when you may have issues with your mass air flow sensor, which is the reason why your engine can either run lean or rich. Thus, the RPM goes up and down not only when you are parked but also while you are driving your car.
And it is also worth noting that the ignition system could be having issues, which lead to this fluctuation concern. You may need to check your ignition control module and spark plugs, which are most likely to be the culprit if the ignition system is to blame from this fluctuation.
When you encounter this problem, a visit to a dealership or a certified mechanic should help determine the actual cause of the fluctuation – and they will provide the best solution to your problem. By conducting some diagnostic tests and looking for error codes, they can give you a definitive answer that will address the issue once and for all.
Let’s look closely at this issue with the RPM going up and down while parked and what can be done about it. Here we go.
Why Does My RPM Go Up And Down While Parked
The fluctuation of your RPM leads to issues with running your vehicle smoothly. It can stall and may lead to malfunctions in affected components. Among the reasons why your RPM is fluctuating are listed below.
1. Idle Air Control Valve Issue
This component regulates the idle speed of your engine. So, when it is faulty, you may notice the RPM is fluctuating. Your IAC valve has a tendency to get clogged up by carbon buildup. Moreover, wear and tear may occur, leading to damage. This is why the valve fails to function or stick correctly.
Carbon buildup starts at your air filters, which may get dirty over time. You may also be using an inferior fuel quality, or perhaps, you have not been driving your vehicle as much. Thus, your IAC valve may have carbon deposits.
Also, wear and tear of the valve happens as time passes by. This is why it becomes less effective, causing your idle speed to go up and down.
Then, there is a possibility of electrical issues with your IAC valve. Some wiring problems may be present, or your sensor may be malfunctioning.
Depending on the actual cause of the problem, the appropriate troubleshooting techniques must be done. For instance, if you have carbon buildup in the valve, then you need to clean this with a wire brush or a specialised cleaner. This way, you can eliminate debris or dirt stuck in it.
However, if the problem is with wear and tear, then the only solution is to get the valve replaced. You can take your vehicle to a mechanic and they will take the old valve out and put a new one in.
In the case of an electrical issue, a professional mechanic will need to diagnose the problem and repair it. It may include replacing a damaged wiring or faulty sensor, as well as getting a replacement for a bad computer module.
2. Vacuum Leaks
If you notice your RPM fluctuates a lot while parked, you may need to check for a vacuum leak. This issue happens when air gets into your engine through a crack or a hole in your vacuum hose or line. This is why the engine may run lean, thus causing the fluctuations in the RPM.
There are many reasons why a vacuum leak happens such as worn hoses, engine gasket issue, or there may be loose connections somewhere. If the problem is with a vacuum leak, then the only thing left to do is to have the hoses checked and replace these when there are significant damages or holes.
3. Throttle position sensor
The throttle position sensor sends information to your computer regarding the throttle’s position. But when it has become faulty, your engine may stall because of an RPM fluctuation. Moreover, there are other issues that can arise such as poor fuel economy and damages to certain engine components.
If you suspect that the problem is with your TPS, then you will need to check for error codes relevant to this component using a diagnostic scanner. You may either rent or buy this tool, or you can just go to your mechanic and have them conduct the scan for you.
To fix the TPS, this may involve certain methods depending on the culprit. If the issue is with buildup to the sensor, then the TPS will only have to be cleaned. But if it is poorly calibrated, adjustments and alignments will have to be done using a specialised tool at the mechanic.
However, if you have a worn out or damaged TPS, you need to replace this component. This is usually a task for professionals, so it is best to take your vehicle to the dealership and have them install a new TPS for you.
Once you have the TPS cleaned, replaced, or adjusted, the next step is to test it to make sure it is working right. A multimeter can be used to test it, then you need to do a test drive with your vehicle and check for any further issues if there are.
The RPM going up and down while parked may be due to a number of factors. This is why the best thing to do is to conduct proper diagnosis of the issue and have the culprit addressed appropriately to ensure the proper working condition of your vehicle and completely eliminate this problem.