There are many reasons why your engine can start running rough, and although some reasons are relatively simple to fix, if it’s not repaired quickly there can be some underlying problems that could be very expensive to repair.
One of the most common causes of engines running rough is defective ignition timing. Incorrect timing can cause several car problems; from a lack of power, and being hard to start to your engine stopping or not starting at all. If your car is running rough, there are a few tests that can point to the problem.
A number of other problems can cause your engine to idle roughly, and we have outlined some below.
- The idle speed may also be set too low: The idle of your engine is like a human heartbeat; if it doesn’t run smoothly, it means there is a problem that needs to be fixed.
- If you have an older vehicle with a carburetor it could be a mixture or a fuel supply issue – a mechanic will be able to adjust your idle and mixture screws during a service, and check your fuel / air mixture is correct
- There may be a vacuum leak –a vacuum leak can cause a rough idle, and these lines are simple for a mechanic to replace
- The Exhaust Gas Recirculation valve might be faulty and should be cleaned or replaced regularly to ensure it works correctly. A faulty EGR valve is not only going to make your engine run rough, but it will also have an environmental impact if not working at 100%.
- Faulty Spark Plugs – Spark plugs build up carbon, which can create a lesser spark. Plugs should be replaced regularly – at each general service by your mechanic, to ensure your vehicle runs correctly and efficiently.
- Faulty Electrical items like rotors, ignition wires or distributor caps can be a cause, and are generally inexpensive items to replace.
- There may be some type of ignition problem – meaning there could be underlying electrical issues that need to be rectified – these can be found through a full engine diagnosis.
- There may be a fault in the computerized engine control system – another issue that can be found through a full diagnosis. This kind of fault if not found straight away can end up being very costly.
- The fuel or fuel injectors may be dirty – this can be fixed by running an additive through your fuel when you fill your tank next.
- Your engine temperature or oxygen sensor could be faulty – to find this issue a mechanic will need to test the sensor with specific diagnostic tool. Sensors are one of the most difficult to find reasons for a rough idle, as there are usually a number of them located in the engine bay.
Whatever the issue is, there is a professional close by that can help. Ask us a question or leave a comment for us below.