Thank you for being a valued part of the CNET community. As of December 1, 2020, the forums are in read-only format. In early 2021, CNET Forums will no longer be available. We are grateful for the participation and advice you have provided to one another over the years.

Thanks,

CNET Support

Question

Spark plugs going bad?

Jun 4, 2017 6:01PM PDT

When I try to crank my car it sputters the first time I try to crank it then starts up after the second try. I have also noticed very very bad mileage recently. Is this because of my spark plugs?

Discussion is locked

- Collapse -
Clarification Request
You'll need to tell more
Jun 5, 2017 6:20AM PDT

Give the car's make and model, mileage and any maintenance history. Also, give information about the mileage you were previously getting versus now. Bad spark plugs usually have other symptoms than hard starting. Tell about drivability. Does the car misfire, backfire, etc. Is it noticeably sluggish when accelerating? Were the plug (and associated wiring) replaced per manufacturer's schedule? As well, fuel mileage tends to increase in Summer and decrease in Winter so comparisons cannot span the seasons. Fuel blends change as do many other factors that contribute to one's fuel mileage.

- Collapse -
Answer
Spark plugs bad
Jun 7, 2017 12:35AM PDT

Most of the times, when you have trouble while starting a car then this is a sign that your spark plugs. You should replace your spark plugs.

- Collapse -
"Let's try this" approach
Jun 7, 2017 6:02AM PDT

I'm not in favor of that. It's not a good troubleshooting technique. Troubleshooting is best done by using one's head first and their wrenches later. Hard starting has way too many possible causes. Obviously, if it's known the spark plugs are past their normal life expectancy, you replace them as part of the repair process. I tend to do the wiring at the same time if these are of the high voltage type. Hard starting can also be fuel delivery issues. Such is why I asked for make/model and history. We don't know if this is an older model with a carburator or a fuel injected engine. The approach is greatly different with engine types.