See Details

25% Off Online Orders over $50

Close (X)

Take 25% Off Your Next Online Order
Use promotional code 25OFF at checkout to receive discount. Receive 25% off your total purchase of regularly priced in-stock single parts or accessories purchased online. Offer is not valid in combination with any other offers, rebates or discounts; not available to Pep Boys' Fleet & Commercial accounts; does not apply to wheels, labor, special order merchandise, tires or the purchase of gift cards. Excludes tires, special order, wheels, outside purchase or sale products Excludes the following brands:Superchips, Hypertech, Edge, Bully Dog, Diablo, Edelbrock, Thule, Holley, Autometer, Accel, K&N, MSD, NOS and BBK Performance. Valid online until 2:59 am EST on 3/8/15. Online orders scheduled for in-store pick up must be completed in store by closing on 3/7/15 for discount to apply.

Haynes Tech Tips - Spark Plugs

 

Are your spark plugs trying to tell you something?

They can tell you a lot about the condition of your engine. If one or more of your spark plugs have sooty black deposits, that cylinder is probably using too much fuel or misfiring. Oily black deposits are often a sign that oil is getting into the cylinder, usually either past the piston rings or the valve guides.

There’s more spark-plug detective work you can do using the color spark plug chart that’s included in each Haynes model-specific repair manual.