Skip the auto shop - Our mechanics make house calls

Q: Engine is misfiring and the service engine soon light is on.

asked by on

My van is missing, especially worse when on load, less when idling. Brought it to a mechanic who diagnosed that cylinder "6" is the problem. He didn't change or fix the problem, said I needed to have several " gaskets " replaced as oil is leaking on the coils and spark plugs of " ALL " cylinders but worse on the "6". Said I have to spend $700-$800 to replace all said gaskets and fix things. Said its quite useless for him to do anything on the "6" alone as whatever he does would soon be messed by all the oil splashing.

I am wondering if this is close to the truth, or just a ruse to squeeze money from me.

My car has 248920 miles.
My car has an automatic transmission.

Hi there.

If the engine is misfiring you would need to check the spark plugs and fuel injectors to see what is not working. If the spark plug has no spark, then check the spark plug wire for spark by-passing the spark plug with a spark tool. If there is spark, then the spark plugs are not working and need replaced. If the spark plugs are firing, then there could be an issue with the fuel injectors causing the engine to run rough and misfire. Remove one harness to each injector at a time (one at a time) and see if the engine stumbles more. If the engine stumbles more, then the fuel injector is working. If there is no change, then the fuel injector is not working and would need replaced. If the fuel injectors and spark plugs are working properly, then there could be an issue with the cylinder. Then you could take a compression tester and check all of the cylinders and compare the reading. They all should be about the same. If number 6 is lower than the rest, then there could be an issue with the head gasket, a burned or sticking valve, or the piston rings are worn causing a low compression. A leak down tester (requires compressed air) will determine the cause and location of a low cylinder compression. If the mechanic did not perform these tasks to determine the expensive repair, then I recommend seeking out a professional, such as one from Your Mechanic, to help you.

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
  1. Home
  2. Questions
  3. Engine is misfiring and the service engine soon light is on.

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: Check engine light flashing, sucking fuel, procrastinating when accelerating...

This is a very odd set of symptoms. I would suggest ruling out any fuel-related issues as the poor fuel economy and lack of power could be related to faulty sensors like the throttle body sensor, mass air flow sensor,...

Q: Muffler

The exhaust is the same except for after the muffler on most of them. The F150 has long and short frames, and I am not sure which one is the same as the Expedition. Your best bet is to get...

Q: Power steering

This may be a result of a broken power steering belt, a leaking pump or a pump that has failed. The power steering system operates on very high pressurized hydraulic pressure (in some cases as much as 300 psi). As...

Related articles

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...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...
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...