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- Vehicle Symptoms
- What Are Common Car Failure Searches?
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- Why Does My Car Drive Weird?
- Why Does My Car Make Noises?
- Why Does my Car smell?
- Symptoms Without Summary
- Car Leaking Coolant
- AC Isn't Cooling
- AC Blowing Hot Air
- Shaking While Driving
- Overheating AC
- AC Smells Like Vinegar
- Heater Not Working
- Windshield Wipers Don't Work
- Car Leaking Water
- Car Leaking Red Fluid
- Car Battery Leaking
- AC Only Work Sometimes
- Shaking While Idle
- Shaking At High Speeds
- Evap System Leak
- Shaking While Braking At High Speeds
- Shaking When Stopped
- Shaking When Accelerating
- Radiator Leaking
- Pink Fluid Leaking
- Car Leaking Oil
- AC Not Working.
- Car Leaking Gas
- Power Steering Fluid Leak
- Bad Brake Caliper
Hey, Why Does My Car Jerk When Accelerating?
If you are short on time and want to fast-track the process to professional help, click Yes
Is Your Car Jerking When You Accelerate It?
Let's Get To The Bottom Of It!
- The mass air flow sensor tracks how much air goes into the engine. It tells the passing air volum...read more
The mass air flow sensor tracks how much air goes into the engine. It tells the passing air volume and speed to the engine's computer. This helps the system determine how much fuel the engine needs to run smoothly, enabling enough power and speed. It also helps reduce pollution. But if the mass air flow sensor doesn't measure the air correctly, other sensors in the engine and exhaust will notice something's off and tell the computer; this can happen due to debris or wear. Then, the check engine light will turn on as a warning. At this stage, the car might commonly sputter when accelerating.
- The engine air filter has an important job: it stops dirty stuff like dust and junk from getting ...read more
The engine air filter has an important job: it stops dirty stuff like dust and junk from getting inside the engine. But if the air filter gets all filled up or blocked because of driving habits and lack of cleaning, air struggles to pass through. This means the engine won't have as much power or speed and will use more fuel, making it less efficient. At this stage, jerks during acceleration are common.
- The spark plug boots have an essential job. They connect to the coil and fit over the spark plug ...read more
The spark plug boots have an essential job. They connect to the coil and fit over the spark plug to protect it from grounding out, preventing a misfire in that cylinder. Unfortunately, these boots are rubber and can deteriorate over time. If this happens, the high-voltage spark can create a carbon pathway along the spark plug and boot, preventing the boots from isolating power. This leads to a misfire in the cylinder and triggers the check engine light to start flashing. In addition, when the engine is under a heavy load, the ignition system has to work harder, making the misfire more noticeable and causing acceleration jerks.
- The transmission control module manages the transmission; it considers how much work the engine d...read more
The transmission control module manages the transmission; it considers how much work the engine does and what the car needs gear-wise. But if, for any reason, the transmission control module isn't working correctly, it can cause the transmission to shift in strange and unexpected ways. This means the car's behavior might become unpredictable, and you may experience random jerks and shifting of gears.
- The fuel pump is like a special pump that runs on electricity and hydraulics. It's inside the fue...read more
The fuel pump is like a special pump that runs on electricity and hydraulics. It's inside the fuel tank, and its job is to ensure enough pressure and fuel flow to the injectors. This way, the engine always has fuel to keep running no matter how you drive. But as the pump gets older, it starts to wear out. This means it won't create as much pressure and fuel flow as before. So, when you try to accelerate quickly, the engine won't get what it needs and will feel like it's stumbling or jerking.
- The throttle body is like a special valve that controls how much air goes into the engine. In tod...read more
The throttle body is like a special valve that controls how much air goes into the engine. In today's engines, it's controlled by a small motor that's controlled by the computer that runs the engine. However, the throttle body can develop problems over time because of wear and heat. This can cause the throttle body to malfunction in certain situations, making it difficult to control the engine when pressing the gas pedal.
Find Professional Help
Please select your vehicle's brand and location so we can locate the best professional help for youVehicle Health Inspection Proof
Explore the following typical inspection results that show a potential cause for the symptom and select the one you believe is similar to your vehicle's issue.
Faulty spark plug boots
Faulty transmission control
Faulty throttle body
Faulty mass airflow
Faulty fuel pump
Poor air filter
The proof image shows the carbon tracking down the spark plug due to failing coil boots. This condition triggers the check engine light on the dashboard.
When the customer brought their vehicle to the shop, they reported that the check engine light flashed when they accelerated to merge onto the freeway. Then, when they reached a steady cruising speed, the check engine light stopped flashing and remained constant. The customer also mentioned that when the light flashes, the vehicle jerks.
The technician confirmed that the check engine light was on during the test drive. Then, they strongly accelerated going uphill, giving the engine a heavy load, causing it to misfire, and activating the check engine light.
During a vehicle health inspection, the technician noticed nothing about the customer's concerns. However, they conducted a scan of the vehicle's computer codes.
They found multiple trouble codes: P0300 (random/multiple cylinder misfire detected), P0301 (misfire in cylinder one), P0302 (misfire in cylinder two), P0303 (misfire in cylinder three), and P0304 (misfire in cylinder four).
With the customer's approval for additional diagnostics, the technician used a specialized scanner for this vehicle. They monitored the live misfire counters while testing the engine by power braking in the service bay.
They discovered that cylinders two and four had the highest misfire counts under load, although misfires were present in all cylinders. The technician then removed the coils and spark plugs for inspection.
Upon inspection, the technician found that the coil boots were cracked and had carbon tracking on the end of the boot and the spark plug. Additionally, the spark plugs were worn beyond the recommended limits. Therefore, it was determined that the spark plug boots and the spark plugs needed replacing.
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The proof image provided shows the location of the failed transmission control module, which has caused the erratic shifting behavior experienced by the customer.
When the customer brought their vehicle to the shop, they expressed concerns about the transmission behaving unpredictably. They mentioned that the transmission would shift randomly and jerk the car, leading to a lack of power.
During the test drive, the technician confirmed that the vehicle seemed stuck in third gear. They also noticed that the check engine light was illuminated.
During a vehicle health inspection, the technician found no further issues. However, they scanned the vehicle's computer codes and discovered a trouble code: U0101, indicating a lost communication with the Transmission Control Module (TCM).
With the customer's approval for additional diagnostics, the technician used a specialized scanner for this vehicle. They found that there was no communication with the transmission control module.
To verify the power and ground connections to the module, the technician accessed them with reading tools and confirmed their presence. This ensured that the transmission control module failed and needed replacement.
2/6
The proof image shows the connector to the electronic throttle body, which has failed, leading to an unresponsive throttle and causing acceleration jerks.
When the customer brought their vehicle to the shop, they mentioned the throttle cable might be broken. They noticed that when they pressed the throttle pedal, the engine didn't accelerate as it should. They also experienced occasional jerking and bucking of the engine.
The technician confirmed unresponsiveness when the throttle pedal was pressed during the test drive. The vehicle idled and didn't accelerate. The technician did notice that the check engine light was on.
During a vehicle health inspection, the technician found nothing to explain the customer's concern. Then, however, they scanned the vehicle's computer codes and found a trouble code: P2119 (throttle actuator control throttle body range/performance).
With the customer's approval for additional diagnostics, the technician used a specialized scanner for this vehicle. Again, they verified the presence of the trouble code and monitored live data.
The technician noticed that the signal from the throttle pedal correlated with the input expected by the engine control module (ECM). However, the throttle body didn't respond as it should.
To investigate further, the technician accessed the connector at the throttle body and used a laboratory scope to test the wires connected to the stepper motor. They confirmed a signal from the ECM to the throttle body. This verified that the throttle body was failing and needed to be replaced.
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The proof image provided shows the location of the failed mass air flow sensor, offering visual evidence of the problem.
When the customer brought their vehicle to the shop, they mentioned two problems: the check engine light was on, and the car had trouble starting. They suspected that the battery might be going wrong.
During the test drive, the technician confirmed that the check engine light was on and noticed the vehicle had sluggish acceleration. They also noticed some jerking when accelerating.
During a vehicle health inspection, the technician found nothing related to the customer's concerns. However, they scanned the vehicle's computer codes and discovered a specific problem code: P0101. This code indicated an issue with the mass air flow circuit's range or performance.
With the customer's approval for additional diagnostics, the technician used a specialized scanner designed for this particular vehicle to verify the P0101 code. Next, they had an assistant drive the car while closely monitoring the live data displayed on the scanner. Finally, the assistant pressed the gas pedal around 45 miles per hour, but the calculated engine load never exceeded 50%.
The technician cleaned the mass air flow sensor and conducted another test drive. On this occasion, the calculated engine load never exceeded 50%, even after cleaning the sensor. This confirmed that the mass air flow sensor had indeed failed.
4/6
The proof image shows the failing pump inside the fuel tank, which has been removed from the vehicle for inspection and replacement. The fuel pump is damaged and can't deliver the proper fuel amount to the car's engine.
When the customer brought their vehicle to the shop, they explained that it acted out of gas when they tried to accelerate forcefully. For example, if they gently pressed the accelerator, the vehicle would gradually increase in speed, but if they pushed it harder, the engine would almost stall.
During the test drive, the technician confirmed that the vehicle wouldn't accelerate properly even when the accelerator pedal was fully pressed. Instead, it would stumble and almost stall. However, the technician didn't realize the check engine light was on.
During a comprehensive inspection of the vehicle's overall health, the technician observed nothing related to the customer's concern. However, they scanned the vehicle's computer codes and found two trouble codes: P0171 (system lean bank 1) and P0174 (system lean bank 2).
With the customer's approval for additional diagnostics, the technician used a specialized scanner for this vehicle. They found that the fuel trims were regular at idle.
The technician connected a mechanical fuel pressure gauge to the fuel rail to investigate further and started the vehicle. They discovered that the fuel pressure at idle was only 40 psi, while the minimum manufacturer specification with the engine running should be 57 psi.
The technician then blocked off the return line and observed that the fuel pressure never exceeded 42 psi. This confirmed that the fuel pump was failing. To replace the fuel pump, the fuel tank would need to be dropped for access.
5/6
The proof image shows clogged and dirty air filters, supporting the technician's findings.
When the customer brought in their vehicle, they mentioned their fuel economy worsened. They used to get around 29 miles per gallon, but now they only get about 25 and the car would vibrate a little. They wondered if the change was because of the winter season.
The customer also told about a jerking sensation from the car, which occurred at that same time.
During the test drive, the technician didn't notice anything directly related to the customer's concern. However, during a vehicle health inspection, the technician found that the engine air filter was almost completely blocked and needed replacing.
The technician used a special scanner designed for this vehicle to investigate further. First, they checked for any trouble codes in the vehicle's modules, but none were found. The technician then monitored live data and noticed that the fuel trims were minus seven.
Notice that the fuel trim values can be positive or negative, indicating whether the ECU (Engine Control Unit) adds or reduces fuel to achieve the desired mixture. In this case, it was reducing the fuel amount.
To confirm the cause of the reduced fuel economy, the technician removed the air filter while the engine was running. They observed that the fuel trims immediately improved, fluctuating between plus and minus three. This verified that the clogged air filter was the reason behind the decrease in fuel economy.
6/6Typical Fixes to Address the Cause(s)
The following chapters bases themselves on experiences from our auto repair shop; we'll describe related problems' causes and fixes.
The AutoTechIQ ranking for Safety, Cost Avoidance, and Environmental Impact is
Vehicle Symptoms
Below are just a few examples of typical Symptoms and Fixes your car might be experiencing
Other things your auto repair shop might talk about:
Fuel injectors. Dirty fuel injectors. Faulty spark plugs. Clogged catalytic converter. Car jerk. Clogged fuel filter. Exhaust system. Bad fuel pump. Engine throttle plate. throttle position sensor. damaged acceleration cables car running smoothly