Low mpg 2000 lesabre limited

[2000ltd]

I have 87k and just did a 195° thermostat and coolant flush. Car runs at 200°F and has new plugs, wires and coils. I've cleaned the MAF sensor with MAF sensor cleaner. Tires are at 38 psi. My dic computer says I get 30 mpg but I checked it at the pump and I get 20 mpg mostly highway miles. I think I may have an issue somewhere and I need help. I don't wanna parts cannon it if possible. Any ideas? All help is welcome.

 

[MelsRegal]

I have 87k and just did a 195° thermostat and coolant flush. Car runs at 200°F and has new plugs, wires and coils. I've cleaned the MAF sensor with MAF sensor cleaner. Tires are at 38 psi. My dic computer says I get 30 mpg but I checked it at the pump and I get 20 mpg mostly highway miles. I think I may have an issue somewhere and I need help. I don't wanna parts cannon it if possible. Any ideas? All help is welcome.

Explain how you checked it at the pump?

 

[2000ltd]

Explain how you checked it at the pump?

I filled up and drove 14 miles then filled up at same pump and checked pump. It said .689 gallons so I divided 14 by .689

 

[RD_Atlanta]

Try to expand expand your test. I prefer to fill the tank then drive until the tank is near empty then refill at the same pump and try to achieve the same fill level.

 

[2000ltd]

Try to expand expand your test. I prefer to fill the tank then drive until the tank is near empty then refill at the same pump and try to achieve the same fill level.

Ok I'll do that next time I fill up

 

[MelsRegal]

I filled up and drove 14 miles then filled up at same pump and checked pump. It said .689 gallons so I divided 14 by .689

I agree with prior comment, driving 14 miles is not a valid test. You have to use close to a tank full to obtain a valid number.

 

[Buckthebuick]

You can see exactly the mpg you just got in short trips if you can keep it FULL, and when you're broke I know how it goes putting in 2.37 in the tank with a mix of pennies dimes and nickels. But if possible financially I'd do this -fill your tank, reset your trip mileage, drive until about ¼ tank. I don't go any lower as I treat my Buick like a baby, but after driving a considerable amount of miles. Usually 300-350 miles from full, fill it again. Take the amount of miles driven. Devide that by the amount of gallons of gas put in the tank and, bam, there's your mileage. I drove 350 miles and put in 13.7 gallons of gas. That's 350/13.7=25.54 I got 25.5 mpg. Unless you can afford to fill your tank every single time you fill up, don't worry about your mileage as it won't matter.

 

[2000ltd]

I retired it like you just suggested and came up with 23.7 mpg after driving a full tank. I'm satisfied with that. It was a mix city and highway. Pretty decent. My 4cyl Mazda gets 28 mixed driving the same route.

 

[JGBuick]

I have 87k and just did a 195° thermostat and coolant flush. Car runs at 200°F and has new plugs, wires and coils. I've cleaned the MAF sensor with MAF sensor cleaner. Tires are at 38 psi. My dic computer says I get 30 mpg but I checked it at the pump and I get 20 mpg mostly highway miles. I think I may have an issue somewhere and I need help. I don't wanna parts cannon it if possible. Any ideas? All help is welcome.

I don't think you have an issue. The computer calculates using many factors and the best way (To calculate mpg) is to fill-up the tank and then drive normally.
The more miles you travel and the more gas you use helps the average MPG. You cannot get an accurate reading by ONLY driving a few miles.

- What RD_Atlanta mentioned above. 👍

And.... whatever you do - Don't OVERFILL your gas tank by trying to get every last drop of gas in the tank. Click, click...click. It's terrible for your EVAP system.

200degs - Great. That's good. 23-28MPG??? Normal.

 

[2000ltd]

I don't think you have an issue. The computer calculates using many factors and the best way (To calculate mpg) is to fill-up the tank and then drive normally.
The more miles you travel and the more gas you use helps the average MPG. You cannot get an accurate reading by ONLY driving a few miles.

- What RD_Atlanta mentioned above. 👍

And.... whatever you do - Don't OVERFILL your gas tank by trying to get every last drop of gas in the tank. Click, click...click. It's terrible for your EVAP system.

200degs - Great. That's good. 23-28MPG??? Normal.

Yep I'm relieved that it came out normal. At 20 I was worried that something was wrong because I've heard of people getting 30 on highway and I was only getting 20. But 23.7 mixed is very good imo

 

[RD_Atlanta]

There is a 'Fuel Mileage Scale Factor' in the PCM which will allow you to scale the accuracy of the DIC displayed MPG but it unfortunately requires adjusting and downloading the program. It sure would have been nice if GM would have permitted car owners to adjust the MPG scale factor via the DIC because it seems they are usually not accurate.

 

[JGBuick]

Yep I'm relieved that it came out normal. At 20 I was worried that something was wrong because I've heard of people getting 30 on highway and I was only getting 20. But 23.7 mixed is very good imo

Yes, sounds about right. Funny thing.... If I'm in the country and filling-up for gas, I'll reset the MPG button and cruise at 60mph on the highway. I will see 33-34MPG if I keep it under 60mph. Just goes to show you how that computer operates.

 

[lilpoindexter]

I have a 2000 that I calculate im getting about 20mpg...BUT...my gas gauge is inaccurate, and I have a lean code that Ive been to lazy/busy to attempt to diagnose. I go by how much gas i put in, and the mileage since the last fill up. My car has 180k. The engine and trans are solid, but the whole car is falling apart around the 3800, and its probably getting close to the end of the line for this thing, so as long as it still moves under its own power, im calling it good.

 

[02LTD2.0]

I live in a busy suburban/metropolitan area and 17.5 mpg is what I see on the DIC.

 

[2000ltd]

I live in a busy suburban/metropolitan area and 17.5 mpg is what I see on the DIC.

You must have a lead foot.

 

[02LTD2.0]

No lead foot but I don't drive like a little old lady either!

 

[2000ltd]

No lead foot but I don't drive like a little old lady either!

Lol

 

[DrivenDaily]

I get 26 or better for all the driving I do and I ain't no little ol' lady or Gramps on Sunday. Just this morning she was spinning over 5ooo RPMs as I "sped up" on the on-ramp for my commute to work.

 

[2003LesabreDriver]

23-27mpg is about as good as I ever got. I also do the method of driving it to 1/4 tank or less and fill it up. Do that a few times to get an average.

Here in the Michigan winters obviously its probably 20-21 mpg or less due to letting the car warm up before driving off.

Overall not bad for a smooth boat ride.

 

[kmart2026]

In my 98 best I ever got was 34.5 mpgs, that was after the third or fourth full tank of 93 octane when I drove to Florida from NY a couple years ago. Average for me most of the time is around 27 highway 23 mixed.