Experiencing a rough start followed by the engine smoothing out can be frustrating with one’s car. Such a problem can confuse the driver while indicating an underlying problem. Here we have listed down the potential causes of why a car starts rough and then smooths out. We have also provided practical solutions to inspect and solve this issue.
Car Starts Rough And Then Smooths Out – Causes
One might come across common car problems daily. It might be engine misfiring, vehicle cranking or unkempt acceleration. One such issue that most drivers face is when a car starts rough and then smooths out. This happens due to several factors and indicates the malfunction of a car part.
We have gathered the reasons why one’s car starts rough and then runs fine. Let’s go through them.
IGNITION SYSTEM AND SPARK PLUGS
Problems with the ignition system due to bad spark plugs or a worn-out ignition coil, can cause a rough start. The engine will initially struggle to ignite the fuel-air mixture, leading to rough running. Once the engine warms up, these components improve performance resulting in smoother operation.
BAD ENGINE COOLANT TEMPERATURE SENSOR
The ECT sensor is responsible for monitoring the temperature of the engine coolant and relaying that information to the engine control unit (ECU) or engine control module (ECM). If the sensor is faulty, it will give incorrect temperature readings or no readings at all.
This will lead to incorrect fuel and ignition settings. As a result, one will experience that their car starts rough and then smooths out.
AIR INTAKE PROBLEMS
A clogged air filter or a faulty mass airflow sensor (MAF) can disrupt the air-fuel mixture, leading to rough starting. As the engine runs and the air intake warms up, the restriction or malfunction may lessen, allowing for smoother operation
DIRTY FUEL INJECTORS
Fuel injectors deliver the required amount of fuel to the engine cylinders for combustion. Over time, these injectors can become clogged or dirty, which affects their performance and cause rough engine starting and running.
Moreover, when fuel injectors are dirty, they spray fuel in an uneven pattern or become partially blocked, disrupting the proper fuel-air mixture. This leads to car engine idling, reduced power, and difficulty starting the engine.
VACUUM LEAK
The vacuum system in a car carries out various functions, such as controlling the air-fuel ratio, managing emissions, and operating the HVAC system. When there’s a leak, unmetered air enters the system, leading to an imbalance in the air-fuel ratio. This causes the engine to run poorly, particularly during startup when the engine needs a precise mixture for smooth ignition.
LEAK IN THE HEAD GASKET
The head gasket is a crucial component located between the engine block and the cylinder head. It forms a seal that separates the combustion chambers from the coolant passages and oil channels.
When a head gasket develops a leak, it leads to several issues that affect the starting process and overall engine performance. Other symptoms of a blown head gasket include overheating of the engine, unusual smoke from exhaust and low coolant levels.
BAD THROTTLE BODY
A bad throttle body causes rough starting in a car due to several reasons. These include insufficient airflow, clogged components, malfunctioning idle air control valve (IACV), throttle position sensor failure, or electronic throttle control (ETC) problems. Such factors disrupt the proper air-fuel mixture due to which a car starts rough and then smooths out.
How to Fix a Car That Starts Rough And Then Smooths Out
Here are some helpful tips that one can use when a car starts rough and then smooths out.
SCAN AND RESEARCH DIAGNOSTIC CODES
Scanning and researching car diagnostic codes helps fix a car that starts roughly by providing information about issues detected by the vehicle’s onboard diagnostic system. The trouble codes act as a starting point for identifying potential problem areas related to the rough starting.
By researching the codes, one can gain insights into the underlying causes and take appropriate actions to address them. This process helps to diagnose the problem more accurately and saves time and effort by focusing on the specific components or systems that require attention.
INSPECT THE IGNITION SYSTEM
A faulty ignition system is among the top causes of a car’s rough starting. Check the spark plugs, ignition coils, and ignition cables/wires for signs of damage or wear. Replace any worn-out or malfunctioning parts.
CLEAN THROTTLE BODY
Here is a step-by-step guide to cleaning a throttle body:
- Gather the necessary materials such as throttle body cleaner, clean cloth, soft-bristled brush, and a screwdriver or socket wrench.
- Locate the throttle body found between the air intake hose and the intake manifold.
- Loosen the clamp and remove the hose to access the throttle body.
- Inspect the throttle body. Check for visible dirt, carbon buildup, or deposits, ensuring the throttle plate is closed.
- Apply a generous amount of throttle body cleaner inside the throttle body, focusing on the throttle plate and surrounding areas. Follow the cleaner’s instructions.
- Use a soft-bristled brush to lightly scrub the throttle plate and interior surfaces. Be careful not to damage any components.
- Use a clean cloth or shop towels to wipe away the loosened deposits and cleaner residue from the throttle body.
- Reattach the air intake hose securely, tightening the clamp.
- Start the car and let it idle for a few minutes to allow any remaining cleaner to evaporate.
SEEK PROFESSIONAL ASSISTANCE
In case one’s unable to diagnose the problem of why their car starts rough and then smooths out, it is time to seek professional help. Several car service centres are spread across the Emirates to resolve vehicle problems. Besides, dubizzle cars inspection services also provide professional and timely assistance.
All in all, these are the potential reasons why a car starts rough and then smooths out. We have also provided solutions to cater to this problem. Also, if you are looking to replace your current ride, these used cars for sale in the UAE offer several options.
Stay connected to dubizzle’s cars blog for more on car problems, maintenance and tips.