2003 Chevy Truck Poor Performance and fuel mileage

2003 CHEVROLET TRUCK

73,000 MILES • V8 • 4WD • AUTOMATIC

ROB HAUBOLD

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My 2003 Chevy 1500HD has a 6.0L in it that feels like it's "pulling hard" all the time. At 60mph it may need to downshift just to climb a hill. Pulling my boat this all gets much worse. Fuel mileage is down, around 6mpg in town and 10mpg highway. Also with cold morning starts I will sometimes get multi-cylinder misfire codes. No body seems to have any idea why including the dealer. They did the recomended throttle body cleaning and sent me on my way. I would be greatful for any advice.

Jan 13, 2009 at 9:05 PM

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GFIMOTORCARS

CAR REPAIR CONTRIBUTOR
673 POSTS

I would definately recommend a tune up. With GM vehicles I have worked on with issues of poor performance and fuel mileage occur usually around 60k. If this is your case a couple hundred bucks in parts and a Saturday may get some much needed kick back in your truck. Start with a new fuel filter and a set of spark plugs and wires. Also get some fuel injector cleaner and send it through the tank. This is also a great time to check your belts and fluid levels. When you change the the plugs note any severe wear on the ends of the spark plug. Here are a few pics to help with spark plug diagnosis. Keep in mind abnormal spark plug wear can cause interesting issues with misfiring, even intermitent one's.

Normal

Oil Fouled

Overheated

Excessive Wear

Ash Deposits

Carbon Fouled

Detonation

Fuel Additives

Jan 13, 2009 at 11:36 PM