Skip the auto shop - Our mechanics make house calls

Q: Cylinders 4 and 5 are misfiring - 2007 Mercedes-Benz S55 AMG

asked by on

In my vehicle, there is a problem that I’m having where there is a misfire on cylinder 4 and 5. I changed the coil packs, but the same misfire is still happening. The problem might be the ECU that sits on the engine. If you need the part number, it is: A2731535079. In your expertise, please tell me what I need to do to fix my car’s problem.

A: Hello. Most of the time if there is a misfi...

Hello. Most of the time if there is a misfire on those two cylinders it is not caused by the computer. Typically it is caused by either failing spark plugs or an internal problem. I usually start by doing a compression test of the engine. If the pressure is low in either of those cylinders then this will occur. If the compression is fine then the spark plug and coils need to be inspected even though they are new. If those are also fine, then the circuit will need to be tested to see if they are getting a good signal. It is common to have a bad connection at the coils which will cause this to occur. If you are going to have this repaired, consider YourMechanic, as a certified mechanic can come to your home or office to diagnose the misfiring problem and proceed with correct repairs.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Flashing Check Engine Light is on. The engine shakes at idle and has low power.

Hi, the first task is to extract the problem codes which are causing the Check Engine light to flash. Most auto parts stores will do this for free. I would suspect plug wires next, and check the condition of the...

Q: 95 grand cher. eng turns over wont start, leave ign on and a few min later fuel pump kicks in but relays under hood make noise the

Hello, thank you for writing in. There are some tests that you can do to make sure that your fuel pump and fuel delivery system is working correctly. These can be time consuming and difficult to do from home without...

Q: ESP and ABS malfunction, shifting issue, brakes locked up

Hello. This can be caused by a number of things. I usually start by scanning the computer for codes to see what shows up. Most of the time, this is caused by a speed sensor at one of the wheels...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the P0052 code means This code is seen when the Engine Control Module (ECM) tries to control the...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...