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Old 05-29-2007, 02:37 PM
PewterPower PewterPower is offline
Hummer Veteran
 
Join Date: Apr 2003
Posts: 56
PewterPower is off the scale
Default New Plugs - Worse Gas Mileage ???

I have a 2003 H2 Lux with 84000 miles. I changed my plugs from the Factory Plugs to the Bosch Platinum Fusion plugs (4509). My gas mileage went from about 9.8 avg to 7.5...... Why would this happen ? I did not change the plugs for any other reason than I thought it was time (past time). I have an Airraid filter in the stock air box.

Any ideas ?
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