The situation when throws the car or jerks when the steering wheel is turned at maximum speed, is a warning sign for any driver. This is not just discomfort that irritates the ear and tactile sensations, but a clear symptom of a malfunction in one of the critical systems of the car. Most often, the problem lies in the hydraulic power steering, but more complex scenarios related to torque transmission or electronics cannot be ruled out.
Ignoring such symptoms can lead to complete failure of the power steering or, worse, to a broken accessory belt while on the road. In this article we will analyze in detail the mechanics of the process, explain why the engine reacts to the steering wheel, and create a diagnostic algorithm. Understanding the nature of these jerks will help you avoid costly repairs in the future.
Modern cars, even those equipped electric power steering (EPS), may exhibit similar symptoms, although the nature of the phenomenon will differ from classical hydraulics. In the first case, we are talking about mechanical resistance and load on the engine, in the second, about software failures or problems with power supply. Let's look at each of the possible reasons in detail.
Physics of the process: why the load increases when turning
When you turn the steering wheel all the way, maximum pressure is created in the steering system. In the classical scheme with power steering (power steering) the pump, driven by a belt from the engine crankshaft, begins to operate at maximum load. The liquid stops circulating through the circuit and begins to overheat, creating excess pressure in the system.
At this moment power steering pump consumes a significant portion of engine power. If the engine is idling, this sudden additional load can cause a drop in speed, which the driver perceives as a jerk or “throwing” of the body. The electronic control unit (ECU) must compensate for this drop by supplying more fuel, but if the system does not work correctly, failure occurs.
It is worth noting that holding the steering wheel in the extreme position for a long time is harmful to the pump itself and the rack seals. The maximum pressure in the power steering system with the steering wheel locked can reach 100-120 atmospheres, which is the limit value for many seals. This is why manufacturers recommend not holding the steering wheel turned for more than 5-10 seconds.
Try not to push the steering wheel against the limiter when parking. Leave minimal play - this will reduce the load on the power steering pump and extend its service life.
Hydraulic power steering (power steering) problems
The most likely reason why the car shakes or jerks when the steering wheel is turned is due to hydraulic malfunctions. If the fluid level in the tank is below normal, the pump begins to capture air along with oil. This leads to cavitation, noise and uneven operation of the mechanism, which is transmitted to the body in the form of vibration.
The second common problem is wear and tear of the power steering pump. Over time, the rotor blades wear out, the bearings break, and the device ceases to create the necessary pressure without jerking. At the moment the stop hits the limiter, the load on the worn pump becomes critical, causing the belt to run out and the pulley to vibrate.
It is also worth paying attention to the condition of the liquid. If it turns black, has a burning smell, or metal particles (shavings) are visible in it, the system must be flushed immediately. Dirty oil clogs the channels and valves, causing the distributor elements to jam.
- 🔴 Low level of ATF fluid in the amplifier reservoir, leading to airing of the system.
- 🔴 Critical wear of the blades or bearings of the power steering pump.
- 🔴 Clogging of the mesh in the tank or the rack valves with wear products.
- 🔴 Pump drive belt tension (too weak causes slipping).
Ignition and idle system malfunctions
If everything is fine with the hydraulics, the reason may lie in the inability of the engine to compensate for the increased load. When you turn the steering wheel, the ECU receives a signal to increase the speed. If Idle air regulator (IAC) dirty or faulty, it does not have time to open the throttle valve, and the engine stalls or trots violently.
Spark plugs and high voltage wires also play a key role. Under load (which is created by the turned on power steering or air conditioning), a weak spark can “break through” to ground. This causes misfire in one or more cylinders, which is felt as severe shaking and jerking of the car.
The throttle body is another candidate for inspection. Carbon deposits on its edges prevent the proper passage of air at low speeds. When you turn the steering wheel, the need for air increases, but a dirty throttle body cannot provide the required flow, causing a rich or lean mixture and unstable engine operation.
How to check spark plugs without disassembly?
Unscrew the spark plugs and inspect them. Black deposits indicate a rich mixture or oil problems, white deposits indicate overheating or a lean mixture. The gap between the electrodes must comply with the manufacturer's specifications.
Diagnostics of CV joints and suspension
Sometimes vibration when turning the steering wheel is associated not with the engine, but with the chassis. If the car shakes while driving with the wheels turned out, it is worth checking constant velocity joints (CV joints). The internal or external grenade may have play, which appears under load.
Problems especially often arise with internal CV joints. When the steering wheel is turned, the angle of operation of the tripoid changes, and if there is wear in it, beating begins. This is transmitted to the body and can be mistakenly perceived as an engine problem. It is also worth checking the silent blocks of the levers and ball joints.
The table below will help differentiate symptoms and quickly find the source of the problem:
| Symptom | Probable Cause | Where to look |
|---|---|---|
| Belt squealing and speed drop | Power steering belt slipping | Belt, tensioner, pump pulley |
| Humming and jerking in place | Power steering airing | Tank, hoses, seals |
| Trembling only when moving | CV joint wear | Drive shafts, grenades |
| Trouble and vibration of the motor | Ignition/IAC problems | Spark plugs, coils, throttle |
If vibration occurs only when driving with the wheels turned, and when parked the engine runs smoothly, look for a problem in the CV joints or suspension, and not in the engine.
Electric power steering (EPS): specifics of problems
In cars with electric amplifier There is no mechanical connection between the pump and the engine, so the load on the internal combustion engine is created indirectly through the generator. If the car jerks when you turn the steering wheel, the electric power steering motor itself or its torque sensor may be faulty.
A common problem is power surges in the on-board network. When turning the steering wheel sharply, the electric motor consumes a lot of current. If the battery is weak or the alternator is unable to cope, the voltage drops, which affects the ignition system and fuel injectors, causing engine instability.
It is also worth checking the software of the EUR control unit. In some models (for example, certain versions Ford Focus or Chevrolet Cruze) there were software “glitches” when the system incorrectly processed the extreme positions of the steering wheel, causing short-term blocking and jerking.
☑️ EUR diagnostics
Self-check algorithm
Before going to the service center, you can carry out initial diagnostics on your own. Start with a visual inspection of the engine compartment. Check the belt tension: press your finger on the longest span of the belt, the deflection should not exceed 10-15 mm. Inspect the power steering reservoir for foam and fluid level.
Then start the engine and listen. If you hear a whistle when turning the steering wheel, there is a problem with the belt. If the noise is in the pump. Try turning off the air conditioning: if the jerking disappears with the climate turned off, it means that the engine cannot cope with the total load from two consumers (power steering + compressor).
Be sure to check the engine mounts. If power unit supports are torn, then any load (including power steering operation) will cause a strong beating of the body, which can be mistaken for engine tripping. Rock the engine with a mounting blade (with the car turned off) and look at the amplitude of its movement.
⚠️ Attention: Never check the tightness of the power steering system with your hand, looking for leaks under high pressure. The spray of oil may pierce the skin and cause serious injury or blood poisoning. Use visual inspection or cardboard only.
⚠️ Attention: If you smell a burning smell when turning the steering wheel, stop using it immediately. This may indicate overheating of the transmission fluid in the power steering or an insulation breakdown in the power steering wiring, which threatens a fire.
When urgent repairs are needed
If the car not only shakes slightly, but stalls every time you turn a parking maneuver, it is dangerous to operate such a car. You may lose control at a critical moment when you need to quickly dodge an obstacle. In addition, constant load surges destroy the crankshaft and connecting rods of the engine.
Urgent replacement is required if a fluid leak is detected from the pump or rack. Loss of hydraulics will make the steering “stiff”, and it will be physically difficult to turn the wheels in place, especially on a heavy car. This is a direct threat to road safety.
In the case of electrics, the alarm bell comes when the “Check Engine” light or the steering wheel icon on the instrument panel comes on in combination with jerking. This indicates that the system has entered emergency mode, and further driving may lead to expensive electronic repairs.
Frequently asked questions (FAQ)
Is it normal for the engine speed to drop slightly when turning the steering wheel?
A small, barely noticeable decrease in speed (by 50-100 units) is acceptable at the moment of sudden load creation, but the ECU must restore it instantly. If the speed drops significantly (up to 400-500) or the engine stalls, this is a malfunction of the idle or power steering system.
Could power steering increase fuel consumption?
Yes, a faulty power steering pump that constantly creates excess pressure or has jammed elements creates a constant parasitic loss of engine power. This forces the ECU to supply more fuel to maintain speed, increasing consumption by 0.5–1 liter.
How often should the power steering fluid be changed?
Manufacturers often say that the liquid is filled for the entire service life, but the realities of operation dictate their own rules. It is recommended to change the power steering fluid every 60,000 km or every 3-4 years to avoid pump wear and jerking.
Why does the car only jerk when cold when turning the steering wheel?
On a cold engine, power steering oil has a high viscosity, which creates greater resistance to the pump. If there are jerks only in the first minutes, this may be the norm for older systems. However, if the vibration is strong, it is possible that the thickened liquid does not have time to pass through the dirty channels.