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Thread: Poor MPG. New plugs, wires next?
08-27-2013, 08:23 PM #1
Poor MPG. New plugs, wires next?
My Avalanche has been averaging around 12 MPG per tank. It's 4x4 with 3.73s, stock ride height, with Diablo 87 octane tune, and a K&N CAI. I made sure I reset the computer by disconnecting the battery after I installed the CAI. Anyways, last weekend I decided to clean the MAF sensor and change out my plugs. These were the stock plugs with 70k miles on them. I replaced them with Denso Platinum TTs (PT16TT) because I figured I'd trying something different. Next might be wires if my mileage doesn't improve much. Any other ideas? Also, what do you think of the plugs below?
-2008 Chevrolet Avalanche LT 4x4 w/ K&N CAI
-2012 Kia Soul !
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08-27-2013, 09:06 PM #2
Are you throwing any codes?
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08-27-2013, 10:15 PM #3
08-27-2013, 10:27 PM #4
Yeah. Mine looked like that after 40,000. But my knock sensors need to be replaced. You don't drive like a bat out of hell I'd assume. Does it have the 5.3 or 4.8?
08-27-2013, 11:46 PM #5
I don't think those plugs look that bad. Other than changing plugs, modern engines don't require much of a "tune up" like they used to. Change the plugs and fuel filter, clean the air filter and keep the tires aired up (go a little above the recommended air pressure on the door, maybe 5 to 10 pounds) and you should be getting most out of your fuel mileage.Clint (TX) 2001 Silverado LS 4.8L auto 2wd ECSB [GARAGE]
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08-28-2013, 02:43 PM #6
08-28-2013, 03:33 PM #7
The plug wires on the 5.3L V8 engines are really short, so they are really easy to replace. I don't know how much they cost, but it can't be that much.
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08-28-2013, 06:09 PM #8
That might be the next thing to do after I take it to the dealer. It's under warranty and I want them to see if there are any recalls or TSBs applicable to it and see if they can find anything wrong with the vehicle and fix it then.
08-28-2013, 06:38 PM #9
Fresh O2 sensors (front ones) might help. I like to change mine when the plugs are changed.
But, the thing that impacts mileage is rolling resistance. Tire pressure, thread pattern, rubber compound, alignment. tight brake pads.
Anything that increases the amount of power required to roll the vehicle will cut into the mpg.Ray
'09 Avalanche LTZ - Black
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08-28-2013, 07:36 PM #10
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