Printable View
hello everyone,
my fathers 2003 yukon has 110,000 miles and for some reason it is only getting 15 mpg on the highway, it has a coldair intake and all maintance is up to date, it use to get 20 mpg. the only thing that has me worried is the trans, it shifts hard and makes some noise, could this be the root of the bad mpg? thank you very much.
Changed the fuel filter lately?
Plugged up cats maybe?
what's the weather like? Both my trucks lose 3-4 mpg when it's cold out...and I generally don't let them 'warm up'. Idle for 1-2 minutes for the oil to heat up, but that's about it.
15 mpg? That sounds great. I haven't got that in three years.
no it hasnt had the fuel filter replaced i will do that next weekend. Is there a way to check for plugged cats? the weather is mid 40s and low 50s, the yukon has always gotten 18-20 mpg no matter the season. And i keep telling my father to let it warm up , but he just fires it up and drives. any more ideas would be most appreciated. thanks again.
O2 sensors with alot of mileage get lazy and will give poor MPG's. But only the upstream sensors.
improperly inflated tires will decrease fuel mileage, too. If he's hauling more passengers or cargo than normal or heavier passengers it will cause a loss of mileage, too. Check the wear pattern on the tires, too. Alignment issues will rob MPG.
i went through the whole suv and everything looked fine, clean air filter, brand new tires inflated to the right pressure. the one thing i havent done is replace the fuel filter, how hard is that to do? thanks for all the help and advice.
not very hard at all. IIRC, the filter has quick disconnects at both ends. it sits at about the left rear door, just infront of the tank. another thing that can also cause poor mpgs is old plugs and wires. i need to do the fuel filter, plugs and wires on my 01, along with replacing my rims. but the rims will get changed next week
i did the plugs and wires about a year ago, i will try the filter. my father is very against putting any more money into this yukon, but i will try. thanks again.
on a 2003 Yukon it has the same fuel filter as the trucks....UNLESS it is Flex Fuel, then it has the quick connect fittings.
This is where I'd go ... doesn't sound through any of the posting these had been replaced. I'm going to be in need of doing mine soon as well.Quote:
Originally Posted by RUFFNECK
Reduce weivht as much as possible. Install a vacuum gauge and keep it as high as possible while driving..
i will pull out the extra seats, and replace fuel filter, how many o2 sensors does the car have, and how many do i need to replace. thanks agian.
The ones they are refering to for fuel mileage are the front two. So you need two of them. They can be called upstream sensors, becuase they are upstream of the cat converters. There is one for each side of the engine and they are the two that are closest to the front bumper.
To answer the rest of the question the truck has four of them. The other two do not effect the fuel trim, they are there to monitor the cat converters and tell the pcm they are there and doing their job. Have you noticed a lack of power? If not then I doubt the cats are causing your lack of mpg. If you are getting gas with more ethanol it will reduce mpgs too.