My Audi A4 Has a Rough Idle

This person is having trouble with their Audi A4 engine idling roughly.

I get a lot of calls from customers looking to replace their engine because it “runs rough.” I’m always happy to sell engines, but I prefer to help folks like this out with knowledge. The truth is, most of the time if an engine runs rough, you’re dealing with a problem external to an engine. Audi engines will commonly run rough if they have coils failing or a faulty ignition coil switch, but the reality is that a leaking vaccuum line, leaking intake manifold gasket, or even a clogged air filter can all cause an engine to run rough. On many vehicles, a dirty throttle body won’t function properly and can cause rough running. If you replace an engine when it’s not the problem, you will still have your original issue – a rough running engine.

Having a good, diagnostic mechanic is one of the best assets a driver can have. If your engine is running rough, you’ve checked the above mentioned issues, and you just can’t pin point the problem, you’ll need a good diagnostic mechanic.

In an upcoming blog article, we’ll talk about how to find a good mechanic. I’ll share a few simple tips that our salespeople have shared with thousands of customers to help them save money and drive with the confidence that their vehicles are ship shape.

  • GarykPatton

    Hi. I like the way you write. Will you post some more articles?

  • A4 Owner

    my A4 engine suddenly devenloped a rough idel that would shakle the car. After a few more days the engine management light came on. I took it to my local Audi garage and after some false diagnosis  one of the “master Technicians” noticed a faulyt “breather system separater valve”. The part cost £6.97 to replace and the engine now idles smoothly and even feels more powerful. My basic understanding of the fault was the valve was causing a lack of air flow into the engine and creating a vacuum inside the engine block. on way to test for this is to try and remove the oil filler cap while the engine is running. If it”s stuck on, you likely have the same issue.

  • Wes

    Hi I have a rough idle no fault codes in module and no engine warning light
    It idles at 800 rpm also noticed my petrol is black in filter