Hi, I just joined this forum and it's very interesting. I own a 2008 Pontiac Montana with a 3.9 liter engin with 98,000km's In the dash it says that it's burning 22.5 liters per 100km. People tell me that it's running to rich. I just got it back from the dealer where they changed the plugs, cleaned the injectors and also cleaned the throttle body. They connected their computer to it and everything seems to be fine. Does anyone have any suggestions what could be causing this problem?
Running Rich
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how are you coming up with that number typically to measure gas mileage you fill up the vehicle, take note of the mileage, drive a 1/2 thank or more and fill it up again and again note the mileage. You then divide the difference in the mileage reading by the number of gallons or liters on the second fill up. So I believe you are saying you are only getting about 4.4 kilometers per liter which I believe is 10.3 miles/gallon ? Is that after all the work the dealer performed? how fast were you driving when you got this mileage number? Did anybody check for a gas leak?
I have done the milage calculation by filling it up before I went to the dealer. The work was done 150 km ago and I still have the same readings in the dash. I will now do the calculations manually again. No, there are no gas leaks and the dealer says there are no vacum leaks either. All my driving is done in the city, I am a average driver (49 yrs old) I'm easy on acceleration and not a hard braker, but there are a lot of stop and go. I have spoke to 2 other people with the same vehicule and they both get 12-13 liters per 100km in the dash.
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the only other thing I can think of is tire pressure but the EPA rating was 16 mpg in the city so that is a big difference from about 10. You do realize your gauge may be wrong which is why you have to calculate the mileage. How are you calculating 22.5 l per 100 k as opposed to calculating kilometers per litter?