Car Shakes When Starting Then Runs Fine

In most cases, shaking is caused by a battery being removed or the starter not working, but it can also be caused by worn spark plugs, dirty fuel injectors, defective motor mounts, or low tire pressure. The problem of the car shaking when first starting and then running fine is common with many cars and car models.  It affects vehicles in all regions but is more common in cold regions.

But,

Why Does My Car Shake When I Start It? 

Shaking during start-up problems can indicate loose parts or burning problems.  Loose engine mounts or low fuel pressure.  Worn spark plugs and low coolant temperature can also be culprits. Shaking can be uncomfortable and needs confirmation even if it stops after a while.  Read on to find out what causes’ vehicle shaking and how to fix it.

This problem has many causes, most of which are related to the engine and its performance.  We have provided some of these reasons and workarounds below.

Regardless of the car you drive and the 10 possible reasons below.  To be precise, worn motor mounts are the most common cause of a car shaking when starting.  This means the engine may shake and move too much when starting.

Before reading further, it’s worth pointing out that several different parts can cause a car to shake when starting, but they’re uncommon, the most common being a worn motor mount.

#1. Engine Failure

An engine misfire is when one or more cylinders in an engine fail to burn fuel, resulting in an incomplete combustion cycle.  Usually, this is obvious to the driver as the check engine light comes on and the engine is very rough.

Occasionally, the engine may misfire momentarily during start-up, but after running it works perfectly fine.  When this happens, by the time the car thinks there’s a problem, the engine management light often doesn’t come on because the problem is fixed and the vehicle drives normally.  Common causes of errors include:

• spark plug problem.
• The ignition coil is bad.
• Failure of the electronic sensor
• fuel supply problem
• Ignition is the wrong solution.

Since it involves interaction with the engine, it should be handled by an expert. A technician must replace the fitting with a new one.

#2. Clogged Fuel Injectors

A clogged fuel injector will not deliver the proper amount of fuel or the correct spray pattern to the cylinder.  Any of these problems can cause incomplete combustion in the cylinder and cause a misfire.  Usually, if your car’s fuel injectors are clogged, the error will appear when the car is running and barely moving.  However, there is a strange possibility that this misfire may disappear after starting the engine.

When starting a cold engine, the ECU uses pre-programmed fuel maps and sensor inputs to determine fuel delivery.  A clogged fuel injector can cause an imbalance in the air-fuel mixture, resulting in a misfire when starting.  This can cause the engine to rattle, run rough, or even stall when starting.

However, the car starts warming up within seconds of starting and the engine management adjusts fuel delivery based on real-time data.  Thus, clogged fuel injectors can be compensated by increasing the amount of fuel in the affected cylinders.  This avoids fuel delivery problems and allows the engine to run more smoothly, masking faults when the car is running.

#3. Spark Plug Problem

The spark plug is responsible for igniting the air-fuel mixture entering the cylinder.  Worn-out or dirty spark plugs can cause misfires.

If the spark plugs are dirty, the engine may rattle when you start it, but then it will run fine.  Dirty spark plugs are often caused by oil that prevents the spark plug from producing a strong spark.  After the engine is started, the heat generated by the engine burns the oil contamination on the spark plug.  Meaning the car will run smoothly now.  However, because the oil has a reason to go into the cylinders when the engine is cold again, the oil again corrodes the spark plugs, and the next time when the car is restarted, the same thing happens again.

#4. Low Fuel Pressure

Without proper fuel distribution, the engine will not function properly.  The fuel is maintained at a specific pressure to ensure the correct amount of leakage into the engine.  If you put the wrong amount of fuel in your engine, it will run rough.

The vehicle may rock when starting as the engine needs enough fuel to start its first combustion cycle.  If the fuel pressure is too low, you may run out of fuel and have a poor fuel-air mixture.  A lean fuel mixture causes a brief misfire when the engine is first started, resulting in an initial shake in the engine.

When the engine is running, fuel pressure stabilizes as the engine control unit uses real-time data and sensors to recognize that more fuel needs to be injected to offset the pressure loss.  Then the engine runs smoothly.  Low fuel pressure can be caused by a variety of problems including:

• Fuel pump faulty
• clogged fuel filter
• fuel leak
• Defective fuel pressure regulator

#5. Worn Motor Mounts

The engine mount has two functions.  One is to secure the engine and transmission in the engine compartment.  The other is to absorb the movements, and vibrations generated by the engine and gearbox while driving.  The most common cause of a car shaking when starting is worn motor mounts.  Also, the vehicle may shake when turned off.

When the motor mounts wear out, the engine shakes excessively and is felt throughout the vehicle.  Excessive engine shaking at start-up due to initial cranking and rotational motion of the crankshaft.  Once the engine is running, there is no pressure applied to the engine mounts except for gear shifts or hard acceleration, so the engine cannot shake much, especially when idling.

#6. Starter Motor Failure

The starter motor lives up to its name.  Its job is to draw power from the battery and turn the flywheel to start the engine.  Since the starter motor is not involved in the combustion process, it produces little violent shaking when you can feel the vibrations.

A starter motor that is not fully engaged with the flywheel will have difficulty starting the vehicle.  That is, the vehicle shakes until it starts.  But after running it is completely smooth.  Also, loose teeth on the starter motor can cause the engine to rattle when the starter jumps over the flywheel and attempts to start.

#7. Loose Parts

Loose parts in any part connected to the engine mean excessive movement of the problematic part when starting the engine. It could be a simple vibration of a loose component that you can feel.  A loose component can result from one of the following issues:

• Loose exhaust system
• Pulsating heat shield
• Loose alternator pulley
• Tensioner pulley lose
• The engine cover is not secure.

#8. Less Oil

A lack of oil can cause problems, but it’s not the actual cause of the engine shaking when starting.  Learn more below.  Oil helps lubricate the rotating engine components and seals the pistons in the cylinders.

Low or no oil in the engine means that without proper lubrication, friction or contact between metal components can cause vibration.  Also, without a sealed combustion chamber, the engine would run erratically.  This is easily observable at first, as when the oil level is low, a small amount starts to circulate after driving.  Just stopping shaking or vibration is enough to protect the engine.

#9. Engine Is Damaged

As mentioned above, running the engine with no or low oil can damage the engine.  If damage occurs, rotating components may become out of sync or out of balance.  It causes vibration or shaking in the engine.

Sometimes a rough ride is only felt at first.  However, with this type of problem, the faster the engine accelerates, the worse the vibration and shaking.  However, it’s still worth noting that damaged engine components can make the transition from stationary to moving much worse than driving.

#10. Expiration

Engine timing means synchronizing the cams with the crankshaft so that everything works at the right time and in a specific order.  The sequence in which the combustion cycle works is that air and fuel are drawn in first, the piston squeezes the mixture, the spark plug ignites the mixture, and then the exhaust is forced out.  Occurring early or late can cause cylinder misalignment or malfunction.

A cam belt or timing chain is responsible for keeping the timing in order.  The belt or chain rotates the crankshaft and camshaft together.  A worn or broken pulley can cause the timing to be slightly off, causing the engine to shake or run roughly when starting.

Normally, why does my car shake when I start it?

I think the most common cause of vibration is a wheel or tire problem.  Possible problems include,

• Improper wheel and tire balance
• Uneven tire wear,
• Separated tire treads.
• Flat tires
• Damaged wheels
• Loose lug nuts.

Other causes of vibration when starting a car

Has your car engine been repaired recently?

If the engine was recently taken apart for repair, it is most likely that the crankshaft was not properly balanced after being installed for repair.  As a result, vibration increases.

After servicing the engine, you may find that imbalances and vibrations can occur due to varying loads on the parts of the cylinder-piston group. The greater the weight difference, the stronger the vibration.

Compression is reduced due to Vale exhaustion.  As a result, the fuel is not compressed properly, the cylinders do not work, the mixture does not ignite or the charge periodically ignites.

In any case, the engine runs at low capacity, and strong vibrations run through the body when starting. I would like to add that many drivers face increased vibration after incorrect installation and tuning of LPG, as an example, when the system does not start the engine on gasoline, but immediately supplies a cold engine with gas.

Finally, there are cases where increased vibration is caused by transmission problems.

Car shakes until warmed up when the engine is cold and wet overnight so the coolant and oil temperatures are close to room temperature.  This causes excessive friction in the engine when starting the car in the morning.  Excessive friction prevents the engine from producing the same amount of power as does high coolant temperature and causes instability.

What are the early symptoms of a car shaking problem?

The problem of shaking after starting can cause serious damage to the vehicle if not paid attention to in time. You can identify the problem by observing a few early symptoms. These symptoms include:

1. Check the engine light on – The engine warning light comes on when there is a problem with the engine. The light should not be ignored as it can be an early sign of a loose engine mount.
2. Leakage – If the fluid is visible under the vehicle, it may be a coolant or fuel leak. By servicing your car, you can stop it before it has a rocking problem.
3. The car that makes you rich – A faulty fuel pressure regulator can cause the engine to overwork and produce black smoke. Low pressure is one of the causes of your car shaking when starting, so have your regulator repaired soon.
4. Error code – If you scan your vehicle with an OBD scan tool and it shows a misfiring trouble code, fix it quickly. Misfiring can occur in the spark plugs, which can cause shaking if not replaced in time.

How to solve the shaking problem?

If you experience any shaking issues, we recommend that you address them immediately. There is a way to solve this problem as below.

• If the vehicle is dead, jump-start the vehicle with a new battery.
• Turn the ignition key a few times before starting the engine to increase the oil pressure.
• Make sure there is enough pressure by adding fuel.
• Recognize Engine Problems Using the Scan Tool

Tips to Avoid Shaking Issues When Starting the Engine

Shake problems are costly and time-consuming to diagnose and repair. So, like many other automotive problems, they should be avoided whenever possible. The following tips will help avoid problems.

• Service the engine regularly and make sure the fasteners are tight.
• Check for leaks and repair them timely.
• Scan the engine for defects.
• Always monitor engine performance in case of spark plug failure.

FAQs

Conclusion

I hope you got an answer to why your car shakes when you start it.  So, don’t pre-apply these tips to eliminate all these causes before actual vehicle shaking occurs. As you can see, there are many reasons why a car shakes when starting, so it’s a good idea to do a full detailed diagnostic on the engine as well as the other parts listed to determine the source of the vibration.  Engine mounts are often the cause of car vibrations, so start by checking the engine mounts first.