Car Hesitates When Warmed Up – 8 Common Reasons And Fixes

An Overview Of Car Hesitates When Warmed Up

The above table only summarizes the reasons and fixes regarding Car hesitates when warmed up. At the same time, the below section provides a detailed insight into the issues and fixes. Now, let’s check them!

Faulty Spark Plug

A weak spark plug interrupts the combustion process. It is not only related to the engine not starting but also causes it to hesitate.

Generally, it helps in burning the fuel that, in turn, starts the engine. Moreover, when the car is warmed up, the faulty spark plug can not produce enough spark for fuel burning. As a result, it causes the car to lag.

However, a faulty spark plug can also lead to engine misfiring, which can cause the engine to lag.

Fix

You can change the spark plug quickly by following the steps given below.

• Step 1: Disconnect the battery.
• Step 2: Open the hood. There, you will find the spark plug at the top of the cylinder.
• Step 3: Pull out the wires from the spark plug.
• Step 4: Clean the area before removing the spark plug.
• Step 5: Use the socket to pull out the spark plug.
• Step 6: Now, put the new spark plug in place.
• Step 7: Turn the spark plug with a socket wrench to fix its position.

Injector Leaking

The injector mainly transfers the fuel to the engine, where the fuel is burnt for utilization.

When the injector has leaked, enough fuel can not be supplied to the engine. As a result, the lower fuel utilization can cause the engine to hesitate as the car gets warmed up.

Fix

Follow the below section to replace the old injectors with new ones.

• Step 1: Disconnect the battery.
• Step 2: Remove the air box to locate the fuel rail.
• Step 3: Now, pull off the cables from the fuel injector.
• Step 4: Use a wrench to unscrew the bolts, tightening the fuel rail. Slightly pull the rail up to get an exact view of the injectors.
• Step 5: Pull out the injector. You can try turning them slightly if they are tightened.
• Step 6: Finally, take a new injector and place it in the hole.
• Step 7: Position the fuel rail in the exact place.
• Step 8: Now, place the bolts to tighten the fuel rail and cover it up again.

Faulty Mass Airflow Sensor

The sensor measures the air intake and makes adjustments to fuel and air.

The faulty mass airflow sensor transfers the wrong signal to the electrical module. As a result, air and fuel adjustment is required in the combustion chamber. Because the ratio should be maintained between the air to fuel and ensure the proper utilization of the fuel.

The ratio of the air to fuel should be 14.7: 1. However, these adjustments may require some time and cause car lagging.

Fix

Quick steps for changing the airflow sensor are given below.

• Step 1: You can follow the manual to find the sensor. Generally, it is located in the air filter housing.
• Step 2: Remove the plug connected to the sensor.
• Step 3: Pull out the sensor after unscrewing the bolts.
• Step 4: Put the new sensor in the hole and screw the bolts.
• Step 5: Now, reconnect the plug.

Faulty Throttle Position Sensor

The throttle position sensor regulates the fuel management of the engine and airflow to the engine.

At the same time, the signal is sent to the ECU, which regulates the amount of fuel to be injected in the injector—and the timing of spark ignition.

When the sensor is damaged, the electrical system can not monitor the correct mixing of fuel and ignition timing. As a result, the engine lags when warmed up.

Fix

Replace the throttle sensor by following the below steps.

• Step 1: Disconnect the battery connections.
• Step 2: The sensor is located on the throttle body.
• Step 3: Pull out the cable from the sensor.
• Step 4: Unscrew the bolts to take out the sensor.
• Step 5: Now, place the new sensor and tighten it with the bolts.
• Step 6: Connect the cable to the sensor.

You can follow the YouTube video below to get a detailed view of the process.

If you find it difficult, you can take the help of mechanics.

Faulty Air Filter

Air filter filtrates the air passing to the engine. This prevents the dirt and debris from getting into the engine.

Well, impure air would affect the engine’s performance and require the engine to make more effort to utilize it.

Consequently, as the fuel burns and the engine warms up, the more effort of the engine might make it lag.

Fix

In order to clean and change the air filter, follow the below steps.

• Step 1: Open the hood and find the air filter. It can be present in a black box called an “air filter box.”
• Step 2: Wipe the box lid so that the dirt can not enter the engine when you open it.
• Step 3: Remove the bolts that are holding the filter.
• Step 4: Pull off the air filter and clean and wipe it off.
• Step 5: In case of changing, place the new filter and tighten the bolts.
• Step 6: Now, close off the box.

Faulty Oxygen Sensor Reading

The air and fuel ratio should be maintained in the combustion chamber to let the engine work fine. A damaged oxygen sensor might insert more oxygen or fuel into the chamber. That can lead to lagging of the engine when warmed up.

Fix

To change the faulty oxygen sensor, you can follow the steps given below.

• Step 1: Disconnect the battery from the vehicle.
• Step 2: In the case of removing the sensor, lift up the vehicle.
• Step 3: Locate the sensor which is placed in the exhaust system.
• Step 4: Pull out the wire.
• Step 5: Unscrew the bolts to remove the sensor.
• Step 6: Insert the new sensor and tighten it.
• Step 7: Tighten the bolts and reconnect the wire.

Faulty Fuel Filter

The fuel filter ensures the flow of contamination-free fuel from the tank to the engine. When the filter becomes clogged, it affects the normal flow rate of the fuel to the engine. Consequently, causes the engine to hesitate. It can occur even when you try to start the car.

Fix

The removal process of the fuel filter is added below.

• Step 1: Battery disconnection is a must.
• Step 2: Lift the car up. Locate the fuel filter which might be placed in the fuel line.
• Step 3: Loosen the clamp and clips that are holding the fuel filter.
• Step 4: Loosen the fuel line fittings and take out the fuel filter.
• Step 5: Now insert the new filter, tighten the clips, and clamp.

Faulty Coolant Temperature Sensor

A faulty coolant temperature sensor can interrupt the function of an engine.

Generally, a coolant sensor monitors the temperature of the coolant mixture. Consequently, the engine’s temperature is kept at optimum by making adjustments.

Here, a faulty coolant sensor may read the wrong temperature. This reading is sent to the ECU, which adjusts the temperature of the fuel mixing, injection, and ignition timing. As a result, the engine takes time to start.

A faulty sensor also causes overheating of the engine. When the coolant temperature is low, increasing the injection rate is required. As the engine warms up, the injection rate becomes excessive, and ultimately, the engine misfiring occurs and hesitates.

Fix

Let’s look at the process of changing the faulty coolant temperature sensor.

• Step 1: Disconnect the battery.
• Step 2: In the radiator system, you can find the petcock. Loosen the connector in the petcock so that the coolant drains before you fix the sensor.
• Step 3: Find the sensor through the user’s manual. Well, it can be located near the cylinder head, near the thermostat, or at the end of the radiator.
• Step 4: Remove the plug connected to the sensor.
• Step 5: Take out the sensor with the help of a socket.
• Step 6: Insert the new sensor and secure it using the socket.
• Step 7: Now, connect the wires back.

What does it mean when your car hesitates to start?

When your car hesitates to start, it could signal underlying issues like a malfunctioning fuel pressure regulator, fuel system clogs, or worn spark plugs. Addressing these concerns by inspecting and maintaining components such as fuel injectors, the fuel pump, or filters can often resolve the problem. Additionally, ensuring proper ignition by cleaning or replacing spark plugs is crucial for efficient air and fuel mixture combustion.