Q: Carbon fouled #3 and computer shows misfire on #3

asked by on

My car had a carbon fouled #3 plug and the computer showed a misfire on #3. I replaced the injector and plugs which solved the misfire and then there wasn’t anything showing on the computer. I began to get a lot of fumes from the exhaust and some light white smoke. In the tail pipe, there is some moisture. I had already performed a chemical test for a blown head gasket and that came back good. The fumes from the exhaust are getting inside the car when I’m driving on the interstate, especially if I’m passing a semi-truck. When I get the exhaust looked at, should they look for leaks or could the problem be something more than that?

If the car is running fine then it will more than likely have an exhaust leak. If the engine is starting to run a little rough again then it may have a valve issue in that cylinder. I would usually do a compression test just to make sure that the engine is fine internally. If it is, then the exhaust needs to be fully inspected because that is the most likely issue.

If you feel like you need assistance with this, contact a certified mechanic who can diagnose your exhaust system and make any repairs that are necessary.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1,000 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!
  1. Home
  2. Questions
  3. Carbon fouled #3 and computer shows misfire on #3

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: My chevy cruze Lt over heats.

You should not continue to drive the vehicle if it is overheating or you may do major engine damage. You will need to have cooling system pressure tested to find where the leak is and then a diagnosis can be...

Q: Possible exhaust leak - 1998 Ford Mustang

Hi there. Most of the time Mustangs tend to have exhaust leaks on the wide pipe where the pipe connects to the manifolds. The part that usually burns up is called a donut. Other times, there are exhaust leaks on...

Q: Security, ABS, and service engine lights on - 2002 Saturn L100

Hello. It sounds to me like you are having an electrical/computer issue with your vehicle. Usually a computer issue that does not prevent the vehicle from running is okay to drive still. Most computer issues only prevent things from working....

Related articles

Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
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...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.