A car that jerks when driving on the highway can be annoying and even dangerous. The jerking motion can make it difficult to maintain control of the vehicle at high speeds and may indicate an underlying issue that needs attention. Though there are several possible causes, this problem is fairly common and can often be remedied with some troubleshooting and maintenance.
Table of Contents
- Diagnosing The Underlying Issue
- How To Troubleshoot The Problem
- Top Fixes To Try
- When To Call A Mechanic
- Driving Habits To Help Prevent Jerking
- Staying Safe On The Highway
Diagnosing The Underlying Issue
The first step is trying to diagnose what exactly is causing the jerking sensation when accelerating on the highway. Here are some of the most common causes:
1. Engine Misfires
One of the most common causes of jerking on the highway is an engine misfire. This occurs when one or more of the engine’s cylinders fails to fire properly. The loss of power causes the vehicle to jerk until the cylinder starts firing properly again. Misfires are often caused by faulty spark plugs, bad wiring, or issues with the fuel injectors. Replacing worn parts can typically smooth out the engine performance.
2. Transmission Problems
Issues with the transmission can also lead to jerky sensations, especially when accelerating at higher speeds. Transmission problems like worn clutches, faulty valves, or low fluid levels can prevent smooth gear shifts. The jerking typically occurs when upshifting to higher gears at certain speeds. Checking the transmission fluid levels and inspecting the overall condition of the transmission is key.
3. Ignition Timing Issues
The ignition timing being off is another common source of jerky high-speed driving. The timing refers to when the spark plugs fire to combust the fuel. If this timing is off, it affects engine performance. Improper ignition timing can stem from a faulty timing belt, bad sensor, or computer timing issues. It requires a mechanic to diagnose and adjust.
4. Dirty Fuel Injectors
Over time, the fuel injectors that spray fuel into the engine can get clogged with deposits that affect their spray pattern and performance. This disruption in the air/fuel mixture can cause intermittent jerking at highway speeds as some cylinders may misfire. Using fuel injector cleaners or having a mechanic inspect the injectors is recommended.
5. Loose/Damaged Engine Mounts
The engine mounts are responsible for smoothly securing the engine to the chassis and absorbing vibrations. If these motor mounts become loose, worn, or cracked, it can affect engine performance and lead to jerking sensations. Replacing damaged mounts restores proper alignment and positioning.
How To Troubleshoot The Problem
If your vehicle starts jerking on the highway, here are some effective troubleshooting steps to identify the issue:
- Test drive under consistent conditions – Use the same highway, speed, and acceleration intensity each time to feel when the jerking happens. This narrows variables.
- Check engine light – The check engine light may illuminate indicating stored engine error codes to investigate. Use an OBD-II scanner tool to read diagnostic trouble codes.
- Acceleration testing – Accelerate moderately at different speeds in each gear. Jerking when accelerating from 40-60 mph for example points to specific transmission issues.
- Shift testing – Manually shift through the gears smoothly with constant acceleration. Jerking when shifting to certain gears indicates transmission problems.
- High RPM testing – Run the engine at high RPMs in park noting any misfires. Misfires point to ignition problems.
- Fuel injector testing – Listen closely for any ticking noises indicating dirty injectors. Use cleaner treatments aimed at deposits.
- Engine mount inspection – Have someone rev the engine while watching for excessive movement indicating loose mounts.
Top Fixes To Try
Once you’ve diagnosed the cause, here are some of the most effective fixes for resolving a jerky car on the highway:
1. Replace Spark Plugs
For engine misfires, replacing worn spark plugs often smoothes out performance. Use manufacturer recommended replacement plugs for optimal firing. Proper gapping and torque when installing is key.
2. Inspect Fuel Injectors
Dirty injectors can be cleaned using specialty fuel injector cleaning products. Completely cleaning or replacing very clogged injectors can stop injector-related jerking.
3. Change Transmission Fluid
Low or contaminated transmission fluid hampers smooth gear shifts. A flush and fluid replacement cleans the system and replenishes protective qualities.
4. Update Computer Software
For intermittent electrical and timing issues, updating the vehicle’s computer software can help. Software updates include programming optimizations.
5. Tighten Motor Mounts
Inspect engine mounts for cracks or loosening. Tightening bolts or replacing damaged mounts reduces engine movement for smoother driving.
6. Adjust Timing Belt
Replacing a worn timing belt and verifying proper camshaft timing helps get ignition timing back to optimal specifications to prevent misfiring.
7. Use Fuel Cleaners
Quality fuel injector and combustion chamber cleaners help remove performance-robbing deposits for better efficiency. Try treatments regularly.
8. Get an Alignment
You may not think about alignments for engine issues, but a proper wheel alignment reduces drivetrain strain which can translate into smoother driving.
When To Call A Mechanic
While some problems can be addressed with simple DIY repairs, a qualified mechanic is recommended if:
- The check engine light indicates major issues after scanning codes
- Transmission repairs like flushes don’t alleviate jerking
- There are symptoms of a major misfire or timing belt/chain problem
- Oil leakage, odd noises, or smoke coming from engine
- You don’t have diagnostic tools or ability to make certain repairs
- The root cause cannot be identified after extensive troubleshooting
A professional diagnostic is especially important for safety when dealing with highway speeds. Extensive engine or transmission damage can occur if issues go unaddressed.
Driving Habits To Help Prevent Jerking
Certain driving habits can actually help minimize jerking by not putting excess strain on engine transmission components:
- Accelerate and shift smoothly – no jackrabbit starts
- Decelerate slowly rather than sudden braking
- Maintain proper speeds – avoid exceeding RPM limits
- Check tire pressure regularly – underinflated tires increase resistance
- Use the recommended octane fuel – lower octane gas can cause knock
- Carry minimal cargo weight – overloading strains the drivetrain
- Perform scheduled maintenance – follow tune-up schedules
Staying Safe On The Highway
If you do experience severe jerking, try to remain calm and avoid overreacting or hazardous maneuvers. Instead:
- Gradually reduce speed
- Activate your hazard lights to alert other drivers
- Gently pull over and off the highway when possible
- Shift to neutral if the jerking intensifies
- Remain alert and keep both hands on the wheel
- If continued operation seems unsafe, contact roadside assistance for a tow
Addressing any car that jerks when driving on the highway quickly leads to a smoother, safer ride. Following proper diagnosing, maintenance, and operating habits reduces strain on components and minimizes the conditions that create a jerky sensation. Remaining attentive to symptoms and cautious when they occur helps prevent exacerbating issues as you get them repaired. With some diligence and care, you can have your car running smoothly for highway driving once again.
- A jerky car on the highway can stem from multiple engine or transmission issues.
- Effective troubleshooting involves testing under consistent conditions to isolate variables.
- Common fixes include spark plugs, fuel injectors, fluids, mounts, timing, and alignments.
- Smooth driving habits help prevent excess strain that causes jerking.
- Stay alert and reduce speed if jerking occurs, pulling off the highway when safe.