Skip the auto shop - Our mechanics make house calls

Q: Car's #8 cylinder is misfiring

asked by on

There is a misfire in my car’s #8 cylinder. Even after changing the spark plugs and the ignition coil, I still have the misfire. When checking the compression in the cylinder, I found that it is good. Also, I checked to ensure that there is 12v going to the injector - that is fine, too. There is a code for the catalytic converter. Could the catalytic converter be causing the misfiring and if not, what do I look for next?

It is possible that your oil ring could be faulty in the number eight cylinder. If the oil ring is faulty, this can allow oil to get past the piston into the combustion chamber and therefore causing it to get burned by the spark plug. This can cause a misfire because oil is much harder to burn than gasoline.

Extended burning of oil by a spark plug can eventually foul out the spark plug. If the oil ring is the only piston ring that is bad, this can still cause the compression readings to be within specification. I would recommend having your number eight cylinder checked by a professional to determine if there is evidence of oil in the combustion chamber. If there is evidence of oil, I would recommend having the oil ring replaced.

Have the vehicle inspected by a qualified mechanic, they will be able to diagnose the misfire firsthand and make the appropriate 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: What is the best exhaust to make my 200 Ford Mustang louder.

Hello. The type of exhaust will really depend on the pitch of the noise that you are looking for. I typically recommend going online and listening to various brands to find what you like. On this vehicle I typically go...

Q: Check engine light on & oil pressure dropped

Hello. It is possible that you are getting a false reading as a result of a faulty oil pressure switch. It is also possible that there is an oil leak and that’s what is causing the oil pressure to drop....

Q: Heater blows cold.

Hi there. Leak stopper should only be used in emergency situations as it usually causes more problems than it "fixes". It sounds like the leak stopper may have settled in your heater core and is preventing the proper amount of...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...