My Envoy's fuel economy has recently gone down the drain, especially on the highway. I have the I6 4x4 with 4.10's. I was getting around 20 mpg (about 500 kilometres on 65 litres of gas) but my last 4 tanks have been around 16.5mpg (430 km's). The only driving difference is that the heater is on now with winter. I thought maybe it was the E15 fuel I had started using so I have run 2 full tanks of non-ethanol but it hasnt changed the economy. About 90 percent of the mileage on a tank is highway speed around 115km/hr. I have 135000 km's now, t-body and fuel filter 2 years (25000km's) ago.
I just had the thermostat changed 3 mths ago as my temp guage was not coming up to temp and I could feel the heater not getting as hot plus It was running a little rough at start-up. The guage was about a tick and a half below where it always is. It had a P0128 code for thermostat so I had it replaced plus the coolant flushed. Dont hate me but I had it done at the dealership that I trust because removing the alternator looked like it was beyond my skill level. Guage is normal now and comes up to temp fast plus it runs smooth again. I talked to the tech and he didn't think the coolant temp sensor needed to be replaced.
I was just reading MichEnvoy's thread about his MPG issues and i am now wondering if my sensor could be causing my issues too. I have not changed my plugs or coils yet although I should start thinking about as I am just past 135000 km's.
Anyone got any suggestions? Should I be looking at the coolant sensor or should I try plugs and or coils first.
Thanks
I just had the thermostat changed 3 mths ago as my temp guage was not coming up to temp and I could feel the heater not getting as hot plus It was running a little rough at start-up. The guage was about a tick and a half below where it always is. It had a P0128 code for thermostat so I had it replaced plus the coolant flushed. Dont hate me but I had it done at the dealership that I trust because removing the alternator looked like it was beyond my skill level. Guage is normal now and comes up to temp fast plus it runs smooth again. I talked to the tech and he didn't think the coolant temp sensor needed to be replaced.
I was just reading MichEnvoy's thread about his MPG issues and i am now wondering if my sensor could be causing my issues too. I have not changed my plugs or coils yet although I should start thinking about as I am just past 135000 km's.
Anyone got any suggestions? Should I be looking at the coolant sensor or should I try plugs and or coils first.
Thanks