s5 4.2l v8 misfire

Audi S5 Engine Misfire [Causes Explained]

Audi Rs5 and S5s are awesome cars generally and from my experience other than oil leaks a few can go wrong, especially with the V6 model but the V8s are also quite reliable.

One of the common issues with these sports cars is engine misfiring, I own one of these and I have had the same issue at some point as a mechanic I figured out the main causes.

In this article, I am going to tell you what causes your S5 to misfire and what you can do about it.

What is Engine Misfire?

In order to understand the causes of engine misfires, we need to first know what it is. Engine misfire is the condition where one or more cylinders in your car’s engine are not firing properly.

This can happen if there is a problem with either fuel delivery, spark plug, or ignition system. One or more cylinders can misfire depending on the cause. Now let’s jump to the s5 misfire causes

What Causes Audi S5 to Misfire?

1. Bad Spark Plugs:

This is the most common cause of an S5 misfire. The spark plugs are responsible for igniting the fuel mixture in your engine. If they are worn out or damaged, they will not be able to ignite the fuel and hence, a misfire will happen.

2. Bad Ignition Coils:

These components are responsible for generating high-voltage pulses that jump across the gap between two electrodes inside each cylinder.

If one or more of these coils fail then it can cause your car not to start at all or misfire badly in a way you feel the engine shaking.

3. Faulty Fuel Injectors:

Fuel injectors are responsible for spraying the fuel into each cylinder just before the spark plugs ignite it. If they are clogged, worn out, or damaged, they won’t be able to spray fuel properly, and this will cause a misfire.

4. Carbon Build UP:

The naturally aspirated v8 model is more prone to this problem than the supercharged model. If you drive your car hard and under load, it can cause carbon build-up on your valves and pistons.

The valves will stick open or closed when they need to be open or closed, respectively, while the pistons won’t be able to compress enough air and fuel into a small space for combustion.

Related Article: Audi S5 4.2l V8 common problems

5. Leaking Valve Cover Gasket:

The Valve cover gasket is responsible for keeping engine oil contained inside the engine. If it’s leaking, it can cause oil to get on your spark plugs and mess with their ability to fire correctly.

I had a few cars in my workshop with the same issue, especially Audis

6. Bad Motor Mounts:

Bad motor mounts are another common issue that can cause misfires.

If your car is shaking or vibrating at idle, then it’s likely that the motor mount is bad and needs to be replaced. Fortunately, the Audi s5 engine mounts have sensors attached to them, so when they do fail, an error code will appear on the ODB scanner.

Related: Audi EPC Light Solved.

Signs of a Misfiring Audi S5 or RS5

  1. Engine Shaking
  2. Bad Idling
  3. Sputtering sound when accelerating
  4. Exhaust Vibrations
  5. Slow Acceleration
  6. Check Engine light Flashing
  7. Cel Light on

What to Do if your Audi Rs5 or S5 is Misfiring

From my experience as a pro mechanic, I recommend that you get an OBD scanner (OBDeleven) or take your car to a diagnostics shop to get it checked.

This way you can find out what is causing your car to misfire before it gets worse. Since an Engine Misfire can be caused by various things getting an OBD scan will help you to know what the cause is.

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