Audi A4 misfiring when accelerating the car

The car jerks when driving - that could be the reason

If you notice that your car is jerky while driving, it could be for different reasons. You don't always have to assume the worst case scenario when the car jerks when accelerating. Every now and then, a look under the bonnet is enough and worthwhile.

Car jerks while driving - check the ignition coils or the ignition distributor

A loose cable can also be the cause of a jerky car. As soon as it is not properly inserted, it will misfire - and the car will jerk. There are several places on the entire ignition system that you can check for faults, such as the ignition coils or, in older cars, the ignition distributor.

  • The ignition coils or the ignition distributor are located in a different place in each car. It is therefore best to trace the ignition cables away from the engine. The ignition coils or distributors are usually located where they end. In rare cases it can also happen that the ignition coils are on the individual spark plugs.
  • Once you have found the component you want, you must first pull the ignition cables off the plugs. After that, you can easily unscrew the coils.
  • Now you can check the contacts of the coils or the distributor on the front and back for corrosion. If the contacts are oxidized, you need to clean them. The "Dremel" DIY tool is best suited for this, of course any other tool that grinds the contacts freely can also be used. After grinding, it is best to spray the contacts of the coils with WD40 so that the contacts remain corrosion-free for as long as possible and good electrical conductivity is guaranteed.
  • If cleaning the coils or the distributor did not help, replacing the relevant parts can also help.
  • Electronics can be very error-prone - so it is best to check the relays for the ignition at the same time. The fuse box can usually be found in the driver's footwell, but there is often a second fuse box in the engine compartment. Clean the contacts of the relays and put them back in the same places as before.

Car jerks while driving - check the ignition cables

A wrongly plugged in cable can also be the root of all evil and result in a jerky car. However, the verification is very simple. First of all, check that all the ignition cables are correctly and securely in place. If not, this is often the fault, since the spark plug is not receiving any power and the affected cylinder cannot ignite.

  • To make things as easy as possible, the best thing to do is to completely dismantle the ignition cables to check for visible damage. It is important that you remember which cable is where on the ignition coils or spark plugs. If you swap the cables, this can have serious consequences; it is best to number the cables.
  • You can often determine internal damage to the graphite cable just by carefully feeling it.
  • Here, too, the contact points to the spark plugs or the coils can be oxidized. However, since these are not easy to clean, it is not worthwhile in most cases. A new set of ignition cables costs around 25 euros, depending on the model and brand.

Car jerks while driving - checking the spark plugs

If you have now dismantled the ignition cables, you can use the opportunity to directly check the contacts on the spark plugs.

  • Loosening or unscrewing these is a bit more time-consuming and requires a bit of dexterity. You often need a special spark plug socket which, depending on the size of the spark plug, must be the right size. If you cannot solve this directly, the WD40 will help you.
  • Once you have removed the spark plugs, you can usually tell with the naked eye what condition the plugs are in. As you can see in the picture, the left spark plug cannot be used. The ignition cable was not plugged in correctly, which meant that it was not properly ignited.
  • If you cannot see any signs of wear and tear, you can clean the contacts of the spark plugs as well as the coils.

Car jerks when driving - check the air mass sensor

The air mass sensor tells the engine of your car how much air is currently being sucked in. If the values ​​are falsified, e.g. due to soiling of the sensor, this can lead to uneven injection of gasoline. It's worth checking out.

  • The sensor can usually be found between the air filter box and the throttle valve in the intake hose. You can often just unscrew and pull it off.
  • You can often see heavy soiling with the naked eye. Now it is advisable to clean it. However, you may only use special air mass sensor cleaners for this. WD40 or brake cleaner often do not dry off completely and can therefore be sucked in and cause damage to the engine.

Tip: Find a cheap workshop near you now

If the initial measures do not help, all that remains is to go to the workshop. With the Caroobi web service, you can find suitable companies in your area - and get repairs at the best price.

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