Ford Focus 3 manual transmission jerks when starting. The car is shaking! Why do valves knock on a hot engine?

In relation to a car, a jerk is a short-term spontaneous change in rotation speed crankshaft engine regardless of the position of the accelerator pedal. IN daily use, as a rule, a series of jerks take place. The limiting case of a jerk (failure) is a noticeable delay in the engine response to pressing the accelerator pedal.

Conventionally, three types of jerks can be distinguished:

At the moment the movement begins;

When accelerating;

With steady motion, i.e. with the accelerator pedal in constant position.

To determine the causes of jerking when the vehicle moves with injection engine Special diagnostic equipment is required, so we recommend contacting a service that specializes in repairing fuel injection systems. However, as practice shows, in most cases jerking is caused by insufficient fuel pressure in the fuel rail or a malfunction of the position sensor throttle valve, built into the throttle body cover. In addition, a specific reason for car jerking Ford Focus 3, equipped with a system electronic control throttle assembly, there may be a malfunction of the accelerator pedal.

If you have some skills, you can determine the cause of jerking yourself.
At the moment the movement begins, the limiting case of a jerk—failure—most often occurs. The most unpleasant sensations are associated precisely with the delay in the engine's response to pressing the accelerator pedal. Sometimes the engine even stalls. A jerk occurs at the moment the throttle valve begins to open, when, based on the signal from the throttle position sensor, the ECU determines the moment of transition from the mode idle speed to the load mode and should increase the amount of fuel supplied through the injectors. If the pressure in the fuel rail is insufficient, even with an increase in the injection duration, there is not enough fuel for a smooth start.

In addition, a jerk can also occur due to a malfunction of the electromechanical part of the throttle assembly and contamination of the throttle valve with deposits from crankcase gases.

The cause of jerks during acceleration may be, as in the previous case, insufficient fuel pressure in the fuel rail. The electronic engine control unit, having received a signal from the throttle position sensor about the intensive opening of the throttle at a large angle, strives to maximize the fuel supply, but due to the reduced fuel pressure it is not able to do this.

In addition to the above reasons, jerks when accelerating a car with robotic box transmissions can be caused by both insufficient quantities working fluid in the box, or a malfunction of the box itself.

Jerks when moving Ford Focus 3

Such jerking is most often caused by a malfunction of the ignition system. Diagnosis and repair are required. Along the way, you can try the following on your own:

Carefully inspect the engine compartment. Turn off the ignition and check the secure fastening and seating of all wires and connectors at the ignition coil and wires high voltage. Start the engine and listen to its operation: the crackling sound when the high voltage current breaks down to ground is weak, but distinct. In complete darkness, the spark during breakdown is clearly visible;

Replace spark plugs regardless of their condition or mileage. Pay attention to the condition of the spark plugs: if it is not up to standard, the engine or its systems may need to be repaired.
A specific cause of jerking during steady motion of a Ford Focus 3 may be a failure of the throttle position sensor built into the throttle cover.

Additional symptoms confirming the malfunction of this sensor:

Uneven engine idling;

Reduced maximum engine power.

The throttle cover is non-removable, so it cannot be repaired. If a sensor malfunction is detected, replace the throttle assembly and cover.

Ford Focus 3. Operation noise valve mechanism engine

Increased clearances in the valve mechanism, clearances due to malfunction of valve pushers or wear of valve mechanism elements	Replace hydraulic lash adjusters and worn valve train parts
Damage to the timing belt or chain	Replace timing belt or chain
Incorrect timing belt or chain tension	Check the tension of the timing belt or chain. If necessary, replace the timing belt or chain

Valve knocking in the engine: causes and troubleshooting

No matter how reliable the car is, the time comes when you are forced to go to a service station to diagnose and repair faults. At the same time, most of the breakdowns can be fixed with your own hands, but there are also those that only professionals can help fix. Valve knocking is a common problem, which in terms of difficulty of elimination is somewhere in the middle. In some cases, it is possible to identify the malfunction and make repairs on your own, while in others you have to turn to a specialist for help.

How to diagnose a knock

Without sufficient experience, car owners sometimes find it difficult to determine the problem by ear. This is not surprising, because the source of extraneous noise can be anything - the crankshaft, bearings, faulty belt and valves. But unlike other sounds, the knocking of valves reveals itself with a characteristic sonority, with a certain metallic tapping, near the gas distribution mechanism. In addition, unusual noise occurs regardless of engine speed.

In practice, it is not difficult to recognize that valves are knocking, but even experienced car owners sometimes fail to diagnose their malfunction. But to confirm or refute suspicions, you can make a diagnosis yourself. To do this:

Lift the hood, then unscrew the cap from the engine filler hole (through which the oil flows).
-Listen to the engine. If the sound volume increases, the valves are causing the problem.
-Place a stethoscope near the part that you suspect is faulty. Using this device, you can accurately determine the cause of extraneous noise.

Causes of knocking

Valve knocking can be caused by many reasons, each of which deserves special attention. Please note that all cars are equipped with a camshaft (at the top of the engine), and the operation of the valves is ensured by the elements of this unit - rods or otherwise called pushers.

So why do valves knock? Let's highlight the main reasons:

Changing the gap between valves and pushers. At car release, the distance between the rods and valves is precisely adjusted. If the parameter deviates from the norm (decrease or increase), a “metallic” tapping sound appears.
-Refueling the car with low-quality fuel. If bad fuel is used, engine detonation occurs, which causes the valves to suffer.
-Lack of oil pressure during acceleration. There are situations when valve knocking appears only when driving at high speed or during acceleration. The reason is insufficient pressure in the engine lubrication system to increase speed.
-Incorrect installation or misaligned position of the timing belt (how to set marks and tension the timing belt).
-Natural wear and tear. If the valves on your car are knocking, this often indicates that the part is simply worn out and needs to be replaced.

Why does valve knocking occur on a cold engine?

When checking, pay attention to one of the main parameters - engine temperature. There are situations when an extraneous sound appears only on a cold or hot engine. If you “link” valve knock to this parameter, you can draw additional conclusions. So, if an extraneous sound appears only on a cold engine, then the reasons are as follows:

Narrowing of the valves. It is no secret that when heated, metal tends to increase in volume, and when cooled, it tends to decrease. For this reason, the distance between the valves (on a cold engine) may be small, and after reaching the engine operating temperature, it returns to the factory setting.
Motor wear. The second reason why valves knock is wear and tear on the engine itself.
It turns out that the gap between the valves and rods does not correspond to the parameter set at the factory, but this only appears on a cold engine. Once the engine warms up, the problem disappears.

Why do valves knock on a hot engine?

If the problem continues to manifest itself after warming up, the reasons may be the following:

Lack of oil in the tank.
- Oil filter dirty.
-Insufficient tightening of the bolts securing the camshaft to the bed.

In addition, extraneous sound can be caused not only by the knocking of valves, but also by hydraulic compensators.

How to adjust valve clearances

The easiest and fastest solution to the problem is to go to a service station and have it fixed extraneous sounds professionals. But, unfortunately, financial resources do not always allow such luxury, and you have to solve problems yourself. There may be other situations when the car owner is interested in tinkering with the car and personally gaining experience in repairs.

If you discover that your engine is experiencing valve knocking and decide to fix the problem yourself, be prepared for some serious work. All it takes is one mistake and the sound will become even louder. That is why a novice car owner should not undertake the task of eliminating knocking. It is important to clearly know the sequence of actions and follow it. To avoid mistakes, read the car repair instructions. A brief algorithm is given below:

Drain the engine oil.
-Remove the cylinder head plug. This is necessary to gain access to the valves.
-Rotate the camshaft so that the mark mounted on the pulley aligns with the installation lug.
- Determine the gap between the valves and rods by touch. At the same time, change the distance using the adjusting washer.
-Turn the washer a certain number of times (here everything depends on the make and modification of the car).
-Return all the parts, then check whether the knocking of the valves has been eliminated or not.

If, after the work has been carried out, the problem has not been resolved, go to a service station and give the car to the experts. In such a situation, it is unlikely that you will be able to adjust the gap yourself. There are situations when the cause of extraneous noise is other breakdowns. But we cannot exclude the possibility that the previous adjustment was performed incorrectly.

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Ford Focus 3. Steam coming from under the expansion tank cap (white smoke)

Cylinder head gasket failure

The most common answer to such a problem is a burnout of the cylinder head gasket (cylinder head), if it is not difficult for you to disassemble the engine, probably the first thought will be to change this gasket. But imagine that there are two more reasons why antifreeze is being squeezed out of the system.

1- This airlock in the coolant system, because of it, not only the stove in the cabin may not work, and this is already a sign of a plug in the coolant - the coolant, provided that your fluid level is normal, but also the thermostat may not work correctly. Which can lead to increased pressure in the cooling system. Well, squeezing out antifreeze.

2- This is a problem related to the expansion tank, and the smart cap of this tank.

To improve coolant circulation throughout the engine system, when starting the engine, a small pressure is created by the pump, which increases the efficiency of the cooling system. If insufficient pressure is created in the coolant system, the engine will heat up faster. Which can lead to boiling or decomposition of antifreeze. When antifreeze boils and decomposes, vapors are looked for weak points. Such as wooden rubber o-rings of the cooling system, bad pipes, a cap that is not tightened tightly on the expansion tank or radiator.

The cylinder head is, of course, also not a minor problem, but it can also be diagnosed and, as it turned out, very simple.

Start the engine, open the expansion tank cap, if idle speed you can see bubbles coming from the main hose, this is one of two things: either the air cap is broken, or there is a problem with the cylinder head gasket.

If this is an air lock, then by extinguishing and waiting for some time you can get rid of it. The most effective procedure is very difficult to describe since you need to carry out a series of sequential actions and it is better to show them on camera.

If there is no plug and the problem is with the cylinder head, then you will have constant or weak bubbling in the expansion barrel or the antifreeze level will gradually drop.
If your coolant is leaking somewhere and there are no traces on the engine, then the coolant may end up either in the cylinder or in the muffler, which also often happens. This indicates a problem with the cylinder head.

Expansion tank malfunctions

First, be sure to look for antifreeze leaks down the barrel; there are three problems with it:

1- the cap of the expansion tank (the cap gasket is stuck) allows air to pass through, and deformation of the cap of the RB-expansion tank also happens - only replace it with the original.

2- the thread of the expansion tank cap is torn off, in this case a new cap will not help for a long time!

3 - the expansion barrel has a leak or has burst at the seam, which manifests itself due to an increase in pressure in the engine coolant system; there are cases that as the internal combustion engine cools, the gap closes and the coolant stops squeezing out.

4- air leak (occurs, but rarely)

The most important thing is a visual inspection for leaks and damage to the hoses.

Pay attention to the thread through which the tank cap is screwed on.

It happens that if you tighten the cap, it becomes crooked and the liquid easily comes out of the tank. If you look at the thread of the tank, it’s not really clear whether it’s intact or not, but if you illuminate it, it turns out that on one side it’s all torn off.

Other reasons

1. White emulsion (foam) on the oil level dipstick or on the oil filler cap indicates that coolant has entered the lubrication system, most likely through a hole in the cylinder head gasket. Sometimes, although rarely, the gasket is intact and undamaged, and the leak occurs due to a crack in the block itself. But in any case, if there is a white emulsion in the lubrication system, you need to sound the alarm, or even better, pick up a tool and fix the problem.

2. White smoke from exhaust pipe When the engine is running, it indicates that coolant has penetrated into the engine cylinder(s). At the same time, its level decreases, since it partially “flies into the pipe.” The car exhaust may be white when the engine warms up, there is a large amount of condensation and high air humidity - this is not a malfunction, but if it always “smoke” a lot - it’s worth thinking about.

3. Oil spots on the surface of the coolant in the expansion tank or in the radiator indicate oil penetration where it is not supposed to be.

The cause is most likely a faulty cylinder head gasket. It's at least worth checking out.

4. Bubbles coming out through expansion tank or radiator indicate penetration of coolant exhaust gases. There is a hole somewhere, and most likely it is in the head gasket. A certain amount of bubbles may appear when replacing the coolant - this is normal, but if the antifreeze is constantly “bubbly”, then something is wrong.

5. The oil filler neck is clogged

6. Antifreeze leaves under the exhaust manifold mounting studs

8. Water from the radiator enters the cylinder block - the radiator needs to be replaced

Hi all!

lexa264
Your problem is exactly the same as mine. It all just started somewhere 1500 km before TO-1 (at a mileage of 12500). On TO-1, all the filters were changed, everything was checked, examined, lubricated where necessary... All maintenance took place in my personal presence. No crime was found.

I will describe in more detail what is happening on my car (FF3 1.6 PS 125 hp Trend Sport sedan, currently mileage 14,500).
1. The first 20-30 km of the trip after a normal overnight stay - everything is perfect (it starts smoothly, drives smoothly, nothing crunches/creaks, etc.)
2. Then it begins:
- I move off smoothly after the traffic light (disclaimer: if the traffic light is short, about 10c, then I leave the gearbox in D and hold the brake, if the traffic light is long, 15-30c I switch the gearbox to N and hold the brake, or put it in P if it’s hard to keep the pedal on slope)
- I feel a vibration starting in the nose of the car
- at the same time, the car does not jerk back and forth, it’s just that some kind of wave begins to move along the body
- approximately at the transition from 1st to 2nd gear, the vibration becomes very noticeable, the steering wheel shakes and the passengers in the car feel
- then the wave of vibration seems to move to the center of the car, weakens slightly and, finally, once again with a noticeable shudder (approximately the transition from 2nd to 3rd gear), fades out with further acceleration somewhere in the area of ​​the gearbox
3. I would like to emphasize that with all this the car moves smoothly, i.e. it feels like it’s just shaking from some strange vibration, but it doesn’t jerk back and forth, it seems to drive evenly
4. You can’t seem to hear metallic clangs
4. More features:
- if you move off sooooo smoothly, well, literally press the gas pedal just a millimeter, then there is NO vibration (well, or very insignificant, which indicates that the engine is straining and starting to accelerate)
- if you press the sneaker into the floor, there is almost NO vibration either
- it happens that the vibration disappears COMPLETELY, even if you do not monitor the position of the gas pedal during acceleration

That is, if you put everything together, the conclusions are as follows:
- the car vibrates noticeably when accelerating, but does not jerk back and forth, drives evenly forward
- this whole thing only appears when the car is warm enough
- there is a certain resonance at a certain position of the gas pedal, which noticeably shakes the car
- it rolls on from time to time, i.e. the malfunction does not always appear

After reading all the topics about vibrations and so on, I figured out the possible options:
- engine mounts are unlikely, because otherwise the symptoms would not appear even when the car is warm (although maybe I’m wrong?)
- I’m not sinning with the box, I looked at everything, it’s dry at the interface with the engine, the firmware is fresh (they re-uploaded it just in case, but nothing has changed); photo:
- here at the joints, too, nothing seems to be flowing; photo: ,

This is the information, comrades! I would like to hear what anyone thinks about this, otherwise I’ve already broken my head trying to identify the jamb myself. Of course, I’ll go to the dealer, but as practice shows, it’s better to tell them what the problem might be, but a lot of time and money will be lost.

P.S. I’ll probably do a detailed report on the completion of TO-1 later and post a link to the topic here
P.P.S. I apologize for the sea of ​​text, good luck to everyone!