Skip the auto shop - Our mechanics make house calls

Q: High speed bogging down

asked by on

So going up a hill at around 75 mph and on flat strips around 100 mph it feels like the car is suffocating for fuel and it bogs down like a sputter. If you keep on the gas it'll just keep with the sputter until you let off and check engine light will flash which I'm assuming is due to it detecting a misfire. I just changed the fuel filter and 91 is always used. Any idea what to check next?

A: Engine misfires can be caused by a list of ...

Engine misfires can be caused by a list of problems, but there are a few suspects that occur more than others. The primary culprits are simple – spark or fuel – usually manifesting in spark plugs, plug wires, the coil(s) or the fuel-delivery system. Spark related problems generally will result from things like ignition coils, crankshaft position sensor, spark plugs, spark plug wires or ignition modules not working properly. When the misfire results from a fuel related issue, this is commonly related to a lean fuel condition (lack of sufficient fuel supply to the motor).

Fuel related misfires can be caused by many different things such as low fuel pressure, faulty or dirty fuel injectors, a faulty O2 sensor, a dirty or failing mass air flow sensor, a faulty or dirty idle air control valve or a vacuum or intake leak. When the fuel supplied to the combustion chamber is insufficient, this results in an ignition (spark) that is igniting a less than balanced load of fuel and air. This results in a misfire or an explosion in the cylinder that is much less powerful than the other cylinders. This creates a loss of power that resonates throughout the motor additionally causing other problems with ignition and fuel timing. I would recommend having an expert from YourMechanic come to your location to diagnose your misfiring problem.

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: Is it dangerous to drive your car with spark plugs misfiring?

To answer your question, yes it is unsafe to drive you car while you are having a misfire. I have provided an article written by one of our professional technicians below. https://www.yourmechanic.com/article/is-it-safe-to-drive-with-a-misfiring-cylinder.

Q: I went to Auto Zone to get the code on my check engine light, is it the same as going to an auto shop?

Hi there. That is probably the same code you would receive from a repair facility. However, that does not provide a diagnosis. The code is only used as a direction for the diagnosis. The computer monitors operating parameters against a...

Q: Car makes sputtering noise

If your car is making grinding noise, and will not turn on then that is a sign that serious engine damage may have occurred. I would recommend having a professional technician, such as one from YourMechanic, listen to the noise...

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...
How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...