Does the engine stutter, does it run unevenly? Common causes & costs!

Recently updated on January 27, 2022 at 10:36 am

Recently, in our report on "Avoid engine damage“Extensive information on what things should be avoided if the engine is to work for a long time. But what if the engine starts to bother? What if you realize that something is wrong? If the engine runs a bit unevenly during the first few kilometers, it can be next to you cold engine also one low outside temperature be the reason for it. This is particularly noticeable in older vehicles, which have a high mileage, and not really something special. However, the engine should run by then at the latest be round, as soon as the Engine is warm.

Does the engine stutter, does it run unevenly?

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1. Rough engine run!
2. Wrong air as the cause!
3. Defective ignition system as the cause!
4. Defective fuel supply as the cause!
5. Motor control as the cause!
6. Other causes!
7. Rough engine run and the HU?
8. Can i continue
9. Tutorials on the topic of "uneven engine running"

Uneven engine running present!

If you visit a workshop because the engine is not running smoothly, they will first check whether each cylinder is running correctly. In addition, the fault memory is read out using a diagnostic tester such as VCDS for vehicles from the VAG Group or similar tools for other brands. Incidentally, one reason for the uneven engine running can also be a Marten bite his. Martens, for example, often bite them Insulation mat the bonnet, which of course has no effect on the engine. But then they still gnaw the ignition cable or Vacuum lines, which are mostly open, this can ultimately result in an irregular engine run. Depending on where the marten “bitten”, you may be able to identify the damage yourself by examining the engine compartment more closely. 

Wrong air can also be the cause!

So that the fuel can be burned efficiently, the Acquisition of the air mass as well as the Forwarding of the air mass to the control unit is essential. These values ​​then serve as the starting point for the mixture preparation. These values ​​can, however, deviate if the wrong air is drawn in, which leads to irregular engine running. There are several reasons for that False air is pulled. These reasons include, for example, a leaking vacuum hose (which in turn can happen through a marten bite), a leaky Crankcase ventilation or a defective seal. 

Defective ignition system is another reason!

The mixture of fuel and air is created by the spark inflamed. If the engine is not running smoothly and it is also a gasoline engine, this can be due to defective spark plugs, for example ignition coils, a defective ignition cable (a marten bite can also be the cause here) or on Humidity in the ignition system. The latter is usually the cause when the out-of-round engine operation only occurs when the humidity is high or when it rains. 

Defective fuel supply is another reason!

For a smooth engine run, the correct amount of fuelthat is injected is decisive. If there are any defects in this area, this can be noticeable by the motor running irregularly. Reasons for a fuel supply that is no longer running optimally are, for example, defective ones Injectors or injectors, an added one Fuel Filter or leaky fuel lines. 

Rough running due to the motor control

Also a broken one Engine control unit can be the cause of an irregular engine run. If this is the case, it can be the case, for example, that the engine either does not start at all, or it just does runs unevenly. A defective control unit can often be repaired by companies that specialize in it, without installing or removing the 300-400 Euro costs. But that's still much cheaper than a completely new control unit. This is also related to various sensors that transmit data to the control unit. If there are defects here, this can lead to incorrect or non-existent values, which ultimately leads to an irregular engine run. This includes, for example, a defective one Air flow sensor, a defective lambda probe or a broken one Camshaft sensor. 

Other causes if the engine goes on strike!

Furthermore, there are a few other causes which can result in an irregular engine run. These include a defective exhaust gas recirculation valve, a broken-in camshaft, a coked one Intake, but also mistakes that the workshop may have made during the last visit. In the end, a common reason is often a unprofessional tuning. For example, if new software has been installed on the engine control unit, the result may be that the engine runs irregularly. The same applies to other components such as a modified one aspiration, Sport camshafts, a modified exhaust system etc. 

Rough engine run and the HU?

As a rule, they do not get through the HU if the engine does not run properly. Because the uneven running of the engine usually also leads to a deterioration in the emissions behavior, which means that the emissions test is not passed. 

Can I continue driving if the engine is not running smoothly?

You should definitely visit a workshop and not drive long distances in order to avoid costly consequential damage or even an economic total loss. If, by the way, you already have a uneven engine running notices, you should refrain from buying the vehicle or at least speak to the seller about it directly. 

Tutorials on the topic of "uneven engine running" 

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