When you start your car, you expect everything to go smoothly. But what do you do when you start your vehicle and it begins to vibrate and shake?
Below, we have highlighted some of the most common reasons for rough idling, and what you can do to fix it.
Basic Mechanical Failure
There are two main reasons why your engine may vibrate or shake when idling, but the causes of these problems vary.
The first issue is an engine misfire. This happens when your engine’s spark plug fires at the wrong time or there isn’t enough fuel or air in the combustion chamber to match the rest of the engine’s performance. If you leave this problem alone, you risk damaging your engine block, forcing you to replace your engine.
The second issue is a mounting problem. Your engine creates a lot of force, which is why the manufacturer mounts it on your vehicle’s chassis so it doesn’t move. But if these mounts aren’t doing their job, your engine will move.
By the time you feel it at idle, the problem is severe enough that you shouldn’t drive the vehicle anywhere before it’s been repaired.
Causes of Car Vibration When Stopped or Idling
There are few problems more irritating than rough idling. But with a bit of know-how and expertise, you can diagnose the cause of your rough idle and get everything back in order in no time.
The most common causes when the car vibrates while stopped or idling are worn spark plugs, faulty engine mounts, a worn serpentine belt, or fuel problems.
Below are the seven most common reasons why a car vibrates when stopped or idling.
1. Worn Spark Plugs
One of the most common reasons for rough idling is worn or damaged spark plugs. If you have worn spark plugs, your engine may misfire, causing shaking or vibrations. If you have a faulty spark plug, you should have a check engine light on your dashboard, but this doesn’t always happen.
The good news is that spark plugs are cheap, but you should replace all of them if one goes bad. From there, you should change your spark plugs every 80,000 to 100,000 miles to prevent this problem from recurring!
2. Loose or Disconnected Vacuum Hoses
Whether you know it or not, your vehicle likely uses vacuum hoses to power the air and fuel systems. If these hoses are torn or disconnected, the systems won’t work as they should, and engine performance may suffer.
It’s not uncommon for an engine to misfire when a vacuum problem becomes severe enough. This misfire is what you notice through vibrations or shaking.
3. Broken or Loose Engine Mounts
Your engine mounts hold your engine in place, so it makes sense that engine mounts could be the problem if you have a shaking or vibrating engine. Inspecting your vehicle’s engine mounts can be tricky, depending on what you drive.
A simple way to check the engine mounts is to open the engine compartment and have someone rev the engine while you watch it. If the engine “jumps,” you have faulty engine mounts.
The engine mounts themselves are relatively cheap, but replacing them can be labor-intensive.
4. Worn Belts
There may be several belts on your engine, but the two that every engine has are the serpentine belt and the timing belt. If either of these belts is worn or damaged, rough idling is a typical result.
Serpentine belts are easier to diagnose and replace. Simply open the hood and identify the largest rubber belt at the front of your engine. Give it a slight pull; if it feels loose at all, that’s a problem.
From there, check for cracks or tears along the belt. If you see signs of damage, replace the belt.
For timing belts, you’ll need a more comprehensive repair, but often you’ll have a check engine light informing you of the problem.
5. Damaged or Clogged Fuel Intake / Fuel Pump / Fuel Injectors / Fuel Filter
If something goes wrong with your fuel system, you’ll likely have a vibrating or shaking engine. This is because if one of the engine’s cylinders isn’t getting enough fuel, it will throw off the entire engine’s balance.
But even if you’ve identified it as a problem with your fuel system, there are several potential culprits. The first place to check should be your fuel filter. If your fuel filter is clogged, nothing will work as it should, and it could even end up damaging other components.
From there, you should look at your fuel injectors, fuel intake, or fuel pump. Many of these issues trigger a check engine light, which can help you narrow down the problem.
6. Clogged Air Filter
Just as fuel is essential for your engine to run properly, air is a critical component. Fortunately for you, if the intake system is the problem causing your rough idle, the issue usually stems from the air filter.
Simply remove the old air filter and check if it’s extremely dirty. If so, that could be your problem. Replace the air filter, reset the code, and see if the problem goes away! Air filters typically cost between $15 and $40, and most auto parts stores will replace them for free.
7. Faulty Camshaft Timing
Engine vibrations and shaking usually mean your engine is misfiring for one reason or another. A potential reason for an engine misfire is bad timing. If you’ve just completed major work on your engine, this is more common, but it’s not unusual to have timing issues if the belt or chain is worn or damaged.
If you need to replace your timing belt, it’s relatively expensive due to the labor involved.
Conclusion
While it might be tempting to ignore a rough idle for a while because your vehicle is still running, that’s the last thing you want to do. The longer you let the problem persist, the more likely it is to turn into something more serious.
Before giving your engine a chance to break, fix the problem! Otherwise, an issue you could have fixed for a few hundred dollars might end up costing you a few thousand.