- Feb 27, 2015
- 574
OK, so I bought my Trailblazer the better part of a decade ago at this point (at least 7 years) it had over 200k miles when I bought it, it's now at 245k and had the transmission replaced 6-7 years ago, the whole time I have owned it it averaged 14.5 MPG, In my research when I was first looking at these trucks I had seen posts on the old site about guys saying they where getting 20-22 MPG on the highway and just could never believe it, I had changed my spark plugs, did the fuel filter (after running fuel system cleaner through it), since it's an 03 and has a fuel filter, replaced the VVT Solenoid since the connector was full of oil, cleaned the throttle body and even went as far as doing the K&N intake as some people claimed to see 1-2 MPG increases with it, all for not, it always has averaged 14.5 when driving it for work and 13.8 driving just to town and back (that chunk of my route is less fuel efficient then town to work), the best single tank average I had ever seen was one time I did a 16.5 MPG average for an all highway driving tank.
ALL these mileage numbers are calculated by hand using the method of filling till the pump clicks off and resetting the trip odometer at each fill up and doing my best to always use the same pump and taking actual miles driven divided by gallons to refill (I have found pumps can vary by as much as half a gallon for where they click off at which is why I always prefer to use the same pump when possible).
Well anyway last weekend (Sunday a week ago) I had to drive out to my tax ladies house to take her a computer I had repaired for one of here customers, truck drove out there fine then when I went to drive to town it felt like it had the occasional miss but wasn't throwing a code or anything, but knowing these trucks (again from my research) can have coil pack issues I said screw it and grabbed an $80 set of new coil packs off Amazon, took it for a test drive and it felt like it had a little more power, so I decided to put it through it's paces and drove it on vacation this weekend, we will ignore the first fill up for now until I fill up again at the same pump to get the overall average of 4 tanks and instead focus on the 2 tanks of fuel, so heading south to my sisters house in North Florida I filled up at the Buc-ee's in Warner Robins, GA from there I drove to her house, parked it for a few days and drove it back, I had 353.5 Miles on that tank and it took 16.876 Gallons to refill at a Shell station about 30 miles south of the Georgia line (I should have waited but never having driven this far on a tank in this truck I wasn't sure I would make the state line or not), I then continue north till I reach the Buc-ee's again and fill up at the same pump I filled up at Thursday night, I had 170.3 Miles on that trip and it took 8.083 Gallons to refill, that calculates out to 20.98 MPG average for an all highway of the flat lands of South Georgia/North Florida from the same Buc-ee's pump as the "control", a basically 4.5 MPG increase over the BEST highway mileage I had ever done before, an over 27% improvement in MPG's, so moral of the story, don't you let anyone tell you the only reason to replace a coil pack is because of a misfire, they do definitely age and will effect your fuel mileage signifigantly, Oh and remember that 21 MPG highway is with 22" SS replica's, so not a light wheel, far more rotational mass, I would be curious to see what it would do with stock wheels and tires but I did the EXT front brake upgrade to the bigger rotor so 16's won't fit anymore, I think with smaller rims and the narrower stock tire width it could do 22 maybe 23.
Can't wait to see what my around town mileage is like now once I refill to clear the highway trip completely.
ALL these mileage numbers are calculated by hand using the method of filling till the pump clicks off and resetting the trip odometer at each fill up and doing my best to always use the same pump and taking actual miles driven divided by gallons to refill (I have found pumps can vary by as much as half a gallon for where they click off at which is why I always prefer to use the same pump when possible).
Well anyway last weekend (Sunday a week ago) I had to drive out to my tax ladies house to take her a computer I had repaired for one of here customers, truck drove out there fine then when I went to drive to town it felt like it had the occasional miss but wasn't throwing a code or anything, but knowing these trucks (again from my research) can have coil pack issues I said screw it and grabbed an $80 set of new coil packs off Amazon, took it for a test drive and it felt like it had a little more power, so I decided to put it through it's paces and drove it on vacation this weekend, we will ignore the first fill up for now until I fill up again at the same pump to get the overall average of 4 tanks and instead focus on the 2 tanks of fuel, so heading south to my sisters house in North Florida I filled up at the Buc-ee's in Warner Robins, GA from there I drove to her house, parked it for a few days and drove it back, I had 353.5 Miles on that tank and it took 16.876 Gallons to refill at a Shell station about 30 miles south of the Georgia line (I should have waited but never having driven this far on a tank in this truck I wasn't sure I would make the state line or not), I then continue north till I reach the Buc-ee's again and fill up at the same pump I filled up at Thursday night, I had 170.3 Miles on that trip and it took 8.083 Gallons to refill, that calculates out to 20.98 MPG average for an all highway of the flat lands of South Georgia/North Florida from the same Buc-ee's pump as the "control", a basically 4.5 MPG increase over the BEST highway mileage I had ever done before, an over 27% improvement in MPG's, so moral of the story, don't you let anyone tell you the only reason to replace a coil pack is because of a misfire, they do definitely age and will effect your fuel mileage signifigantly, Oh and remember that 21 MPG highway is with 22" SS replica's, so not a light wheel, far more rotational mass, I would be curious to see what it would do with stock wheels and tires but I did the EXT front brake upgrade to the bigger rotor so 16's won't fit anymore, I think with smaller rims and the narrower stock tire width it could do 22 maybe 23.
Can't wait to see what my around town mileage is like now once I refill to clear the highway trip completely.