MPG Dropping??

pektel

pektel

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Hey guys, just a quick question. Hoping someone might be able to point me in the right direction. 2000 V8, 106K. I noticed a couple weeks ago that my average mpg dropped quite substantially. I used to average 18-19 mpg. I reset it about a month ago, just because i was curious. Well, now it averages 14.5 mpg. What would cause such a drastic change, and so quickly?

Thanks in advance-
 
drive on the highway less? or a change in driving habits? A mix of highway and city driving and then resetting and just doing mostly city driving can do that.
 
What glanga said. Plus, depending on where you're from, they change the gas formula for the winter time which equals less MPG.
 
camthman said:
you done the 100,000 tune up? (plugs, fuel filter, tranny, ect.)
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No, I didn't do the 100K tuneup. But just those few things you listed sounds like a high maintenance bill at the dealership! I guess if i can find someone with a heated garage, I could take a day and do that stuff. What else does Lincoln recommend for the 100K mile service?
 
NYC LS8 said:
What glanga said. Plus, depending on where you're from, they change the gas formula for the winter time which equals less MPG.
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I never knew that. If they change it for cold temps, then F***ing right they change the formula. We already had sub zero temps (with wind chill) here. Would that formula change equate to 4 less mpg?
 
I noticed the same thing too, back when I just learned about resetting the fuel economy reading.

glanga said:
drive on the highway less? or a change in driving habits? A mix of highway and city driving and then resetting and just doing mostly city driving can do that.
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+1
 
They change the formula to reduce winter pollution; in most states they add 10% ethanol. In NV it is from October thru February. When it is cold you car runs rich until it is up to operating temp.
 
I would start there. There is a link somewhere around here that tell what to do at 100k. Just search.

pektel said:
No, I didn't do the 100K tuneup. But just those few things you listed sounds like a high maintenance bill at the dealership! I guess if i can find someone with a heated garage, I could take a day and do that stuff. What else does Lincoln recommend for the 100K mile service?
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They used to add MTBE (Methyl Butyl Tertiary Ether) to gas in NH, but the state made them change the law requiring it, due to massive abilities to pollute groundwater from fuel spillage. I don't know if it is still used elsewhere. It's an oxygenator that makes cold engines burn cleaner that is also readily absorbed by water, which showed up in a lot of folks wells. It was typical to lose 2-3 mpgs. The pumps had to be labeled "Contains MBTE" while the tanks were storing that gas. Now with ethanol added, it does the same thing but without the lingering pollution that comes with spills. Also, E85 gas is said to be around 100 octane, and much cheaper than racing gas, but with similar results at the track, allowing advancing the spark without pinging. Unfortunately, the MPGs can be as much as 20% off or higher, but still much cheaper to operate at the track than racing fuel.
 
milehighmikey said:
They used to add MTBE (Methyl Butyl Tertiary Ether) to gas in NH, but the state made them change the law requiring it, due to massive abilities to pollute groundwater from fuel spillage. I don't know if it is still used elsewhere. It's an oxygenator that makes cold engines burn cleaner that is also readily absorbed by water, which showed up in a lot of folks wells. It was typical to lose 2-3 mpgs. The pumps had to be labeled "Contains MBTE" while the tanks were storing that gas. Now with ethanol added, it does the same thing but without the lingering pollution that comes with spills. Also, E85 gas is said to be around 100 octane, and much cheaper than racing gas, but with similar results at the track, allowing advancing the spark without pinging. Unfortunately, the MPGs can be as much as 20% off or higher, but still much cheaper to operate at the track than racing fuel.
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MBTE is a highly carcinogenic and I believe banned for all the reasons milehighmikey stated.
 
I also have noticed that my Fuel Tank isnt lasting enough...and i drive the same miles everyday and I drive equal everytime...

I changed the Fuel Filter @ 45k and know have 76k should I replace it again?? or wait till 100k?
 
pektel said:
I never knew that. If they change it for cold temps, then F***ing right they change the formula. We already had sub zero temps (with wind chill) here. Would that formula change equate to 4 less mpg?
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If I remember correctly, BFE is somewhere pretty close to me. If that's the case, no, the winter gas wouldn't account for a 4mpg drop. I did notice a drop from a steady 18.7-19.2 down to a steady 18. So I've only lost about .5 mpg over the course of the last 2 weeks. Do you let your car idle for long periods of time? I'd say it's the 100k tuneup, though.

I neglected to get the 60k tuneup in the old '03 F150 because "it's running fine". Until I was in Brainerd (3 hours from home) and it started to misfire and wouldn't idle. Turns out one of the plugs was completely shot. Luckily I was able to make it home. But I learned a lesson. Spend the $100 or whatever for the maintanence less you get stranded somewhere. Especially in the winter!
 
milehighmikey said:
Also, E85 gas is said to be around 100 octane, and much cheaper than racing gas, but with similar results at the track, allowing advancing the spark without pinging.
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The LS can handle the 10% blends, but its fuel system is not compatible with E85. As I understand it, only vehicles with the "Flexible Fuel" badge are E85-compatible (AFAIK, there are no flex-fuel LSes).

As mentioned above, driving habits and changes to seasonal gas blends have the greatest effects on your mileage. Additionally, it is normal for the readings on the MPG display to change quite drastically after a reset; it's a running average, so the longer it runs, the less susceptible it is to sudden changes, and vice-versa. It's entirely possible that your mileage has been lower for some time (though mileage that low would probably have made your MPG readout be on the downhill slide). The only way to know your true mileage is to record your mileage and the amount of gas you put in the tank at each fill-up (which also means you should always fill 'er up, as a partial fill will provide a useless data point).
 
arent you supposed to change the fuel filter everytime you do a tune up? how often do you have to change the fuel filter?
 
I forgot to add in that in cases of extreme temperature differences in a short time span, make sure that your tires are rolling at their least level of resistance by topping off your tires to the correct pressure. In our case in NH, it's gone from 50s to teens in a matter of a week or two, so if you were sporting 32-36 psi at 50 degrees, you wouldn't be to close to that now, due to the contraction of the air inside the tires.
 
You know, I was thinking that it's not really the blend that is killing the mpg. I let my car warm up for 10-20 minutes every time i go somewhere. I bet that has a significant effect on my mileage.

I called the dealership for what they do at 100K. The only things the service department told me were: Oil and filter change - $40; Platinum Spark Plugs ($354 with labor), and tire rotation. $354? Bulls**t! I'll do that myself! But I was thinking about changing the fuel filter. Dealer wants $50.
 
Hey pektel, you never answered my question. Im sorry but I really dont think changing gas mixtures would cause a drop that significant. I drive the highway a lot, and when I don't for a while my avg mpg will drop, but as soon as I do the highway again it will climb back up. I really think thats your problem.


I would change the plugs and wires, give it an oil change, and possibly check or flush antifreeze since winter is almost here?
 
Sorry, glanga. I just changed my cylinder head temp sensor & thermostat, so naturally I changed the coolant at that time.

And my driving has been almost the same. No extra driving, and i take the same roads to work every day. I suppose i don't go on any road trips right now. But before I was only going on trips (less than 200 miles) about once a month.

I did get a drop in K&N for the stock air box a couple months ago, and drove with a heavier foot for a little while to see if i could notice a difference - I didn't notice a difference, but i needed a new filter anyways, so no harm done.

Thanks for the help though!
 
Oh, and oil and filter were changed 2000 miles ago. I am going to change the plugs. If i do the wires, that means new boots, too right? Since they are COP? I've never looked, so i have no idea
 
pektel said:
You know, I was thinking that it's not really the blend that is killing the mpg. I let my car warm up for 10-20 minutes every time i go somewhere. I bet that has a significant effect on my mileage.
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Yeah, using that much gas while going nowhere will kill the mileage. :D Like any arithmetic mean, it's really easy to lower it, but difficult to raise it; however, you can "cheat" it--if you want it to look better, wait 'til you're cruising on the highway and reset it. It'll still come down when you get off of the highway, but it won't be down in the cellar like it is now...
 
First off, waiting 10-20 mins is WAY to long to let your car warm-up. Your just wasting gas. You just need to wait a few mins for the "cold start emissions" to do its thing.

Secondly, Pull your fuel filter out and blow through it. If its pretty easy your fine. If there is SOME resistance you might as well replace it sense you already have it out.
 
camthman said:
First off, waiting 10-20 mins is WAY to long to let your car warm-up. Your just wasting gas. You just need to wait a few mins for the "cold start emissions" to do its thing.
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That's what I did last winter. This winter there was a big change. I now have a 4 month old son, who i'd prefer to be warm in the car, instead of crying and cold while it warms up, and i'm on the road.
 
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