Skip the auto shop - Our mechanics make house calls

Q: Check engine light code for a misfire

asked by on

I have a check engine light the code was saying i had a misfire in cylinder 5 i replaced all plugs and wires did an oil change it runs a lot better and quiet but my gas milage is horrible is this normal i have mud tires on my.truck not sure if this is a problem.and i still have a check engine light on like i said it runs a lot better i also put a new air filter in why would my engine light still be on. I replaced everything i needed to for the code

My car has 245000 miles.
My car has an automatic transmission.

A: Hi there. A misfire code is set when the en...

Hi there. A misfire code is set when the engine computer sees a slow down in one or more pistons due to incomplete combustion. This can either be from a lean or rich condition. The task at hand is to accurately determine what is causing the misfire. Check for a crack in the distributor cap or rotor and replace as necessary.

There could also be a leaking injector that is pouring fuel instead of misting. This may account for the horrible gas mileage although the mud tires may contribute.

If I’m not mistaken, this model also has a cold start injector. Verify if the location of the cold start injector is in line with cylinder 5 intake port as a leaking cold start injector would also cause the misfire in conjunction with the gas mileage concern.

I strongly suggest having a qualified technician perform an inspection to prevent replacing unnecessary parts. If you would like to have this done, a certified professional from YourMechanic can come to your car’s location to diagnose the misfire and follow through with 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: I am looking for a sunroof

Hi there: Unfortunately, the replacement sunroof business for vehicle's 20 years old is not as open as most auto part replacement items. Your best bet is to search locally on Ebay.com if you're in the United States, or through local...

Q: My van is doing some weird things like misfiring down the highway.

Hi there. It sounds like the alternator is seizing up and needs replaced. This would explain the lights dimming and the smell of burnt rubber. Also, if the power steering pump was to seize up, it will cause the engine...

Q: What causeing a car spit and pudder and wants to die

Hi there. There are multiple reasons why a car can have issues sputtering, running smooth, and eventually shutting off. The most common include vacuum leaks, bad fuel sensors, dirty fuel injection nozzles, worn out air filters, damaged spark plugs, and...

Related articles

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...
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...
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...