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sartech
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| Posted: Oct 15 2008 at 8:41pm | IP Logged
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I know this is RIDICULOUSLY overtalked, but I was hoping for some pointers in this stupid issue. The lowdown, I had a sudden drop in fuel mileage from 11.7 L?100 km to 14.2 L?100 km.
Necessary info, one tank after running half of a tank of ethanol blended fuel, two tanks before installing Fitch Fuel Catilyst, two tanks after installing skid plates, 30,000 km after installing mud terrinas of stock size, one tank after installing 1.5" lift. The confusion is that I tought it might be due to running ethanol fuel in it. So I only ran 1/2 tank on it and then refilled with regualr gas. I went offroading that day and thought the mileage may be due to that too. I have since aired up my tires again and run two tanks of regular fuel and there is no increase. It just dropped and has stayed there. Could there be something related to the charcoal canister, MAF sensor, O2 sensor, timing, etc?
I have since washed it meticulously and there is no extra weight or dirty air filter or low tire psi. I have also left the battery disconnecte for quite awhile to try and reset the computer and seems like it did not help. Any guesses? This is a huge drop and not linked to anything as far as I can tell. Now I'm scared to drive it at all!
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Boomer
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| Posted: Oct 16 2008 at 4:46am | IP Logged
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Fuel catalyst? Save your money. What it is doing, I have no idea but at best, it is nothing.
A lift changes the front profile, allowing more air under the vehicle. This can cause mileage to decrease by increasing under vehicle turbulence. It is why race cars run air dams that barely clear the road. I think this is the most likely candidate.
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S.A.R.Tech
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| Posted: Oct 17 2008 at 11:26pm | IP Logged
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mmmmm, thought a lot about that. But then I didn't think it was the culprit b/c it happened only after a couple of tanks had been run through with the mild lift installed. \i have also full skid plating which should really smooth the airflow out, or so I thought. \i was also very carefull to maintian the factory rake (forward attitude of the truck) \i did not level it out, just lifted it equally front and rear. Does 1.5" really make that big of a difference?
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Boomer
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| Posted: Oct 18 2008 at 8:04pm | IP Logged
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Lift kits affect on MPG - Page 2 - ThumperTalk
I found this set of responses on this subject for you on another Web site. Thought they were interesting. Hope it helps you think about this! I have read a lot of articles that talk about "messy" air flow under the vehicle affecting mpg adversely. Not something to be ignored.
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S.A.R.Tech
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| Posted: Oct 18 2008 at 9:37pm | IP Logged
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great work, thanks for the link. I have to admit that \i was just shocked it would affect me so much. I expected a little bit, but not quite so much. I guessI was luck to begin with seeing as how I lost no MPG after adding my mud terrians, which were at least twice a heavy as the stockers. Maybe she was running right on the brink and that pur her over. Guess it\s gonna be really hard to tell whether the Fitch fuel works or not and how much. Every report I have heard and seen syas it works, at least a little bit. Even if I gain 1 MPg it will pay for itself in under a year; better than nothing.
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frontierguy
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| Posted: Oct 19 2008 at 8:46pm | IP Logged
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How aggressive are the tires compared to stock? Also, it's getting colder up in Canada- cold/lower mpg.
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S.A.R.Tech
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| Posted: Oct 19 2008 at 9:58pm | IP Logged
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I am running interco truxxs m/t. stock size but way more aggressive. i have had them for almost a year now though. i am starting to cup really badly since the dealership "serviced" for me last time. It is dropping up her but still no widle warm up in the mornings, soon though.
That is why I was wondering about stuff like the charcoal canister (evap can), MAF, MAP, timing sensors like the cam reference sensor and the thing that adjust the valve timing and intake.is there a way to reset the computerto factory settings? do our trucks have the learning capability?
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fronty4x407
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| Posted: Oct 30 2008 at 8:02pm | IP Logged
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MPG Drop here as well
I
have a 2007 frontier SE Crew Cab 4X4 and have recently made the
following mods to my truck..... 1. 18" rims (comparable weight to stock
ones) with goodyear wranglers 265/50R18 (same aspect ratio as stock).
2. OEM roof rack. 3. Nismo CAI (no exhaust changes).
I was previously getting 20-23mpg and now am getting 17ish.... I didn't
think that the tires/rims would impact my MPG since they are the same
overall size as the stock ones or the roof rack since there isn't much
to catch the wind.... with my CAI, i thought it would improve MPG if
anything.....
Could my Mass Air Flow sensor be malfunctioning?
Other info: tires at max psi, 70mph, no other changes made to my truck/driving. 31K (just had the 30K service done)
Thanks for any help/advice!!
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Boomer
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| Posted: Oct 31 2008 at 4:37am | IP Logged
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Heavy tires with aggressive treads and roof racks both are detrimental to mileage. Rolling resistance can be higher and overall weight of the tire/ wheel is higher requiring more fuel to get going and more brake pad wear to get stopped. Roof racks will disturb air flow and the bigger they are, the worse it gets. Add to this winter blend gas, ethanol in gas and cold starts in the morning and you can see mileage drop. Remember, there is a reason under CAFE that car/truck manufacturers use the tires, aluminum blocks/heads and body profiles they do. All of these contribute to higher fuel economy to get the fleet average up.
Take all unnecessary weight out of your truck, keep the speed at 60-65 mph (wind resistance goes up with the CUBE of speed) as going 70-75 is very detrimental to mpg. Use syn fluids like Mobil 1 motor oil and in the winter, switch to 0W-30; it helps mpg during startup/warmup. Put Mobil 1 diff fluid of the right viscosity in your rear diff. Try going up a grade in octane rating if you are using regular gas.
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2007 Nissan Frontier SE 4X4
Crew Cab, short bed,
2003 Saturn L-300 sedan
2013 VW Passat TDI
State College, PA
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fronty4x407
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| Posted: Nov 03 2008 at 1:43pm | IP Logged
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Boomer wrote:
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Heavy tires with aggressive treads and roof racks both are detrimental to mileage. Rolling resistance can be higher and overall weight of the tire/ wheel is higher requiring more fuel to get going and more brake pad wear to get stopped. Roof racks will disturb air flow and the bigger they are, the worse it gets. Add to this winter blend gas, ethanol in gas and cold starts in the morning and you can see mileage drop. Remember, there is a reason under CAFE that car/truck manufacturers use the tires, aluminum blocks/heads and body profiles they do. All of these contribute to higher fuel economy to get the fleet average up.
Take all unnecessary weight out of your truck, keep the speed at 60-65 mph (wind resistance goes up with the CUBE of speed) as going 70-75 is very detrimental to mpg. Use syn fluids like Mobil 1 motor oil and in the winter, switch to 0W-30; it helps mpg during startup/warmup. Put Mobil 1 diff fluid of the right viscosity in your rear diff. Try going up a grade in octane rating if you are using regular gas.
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Thanks for your suggestions, I will look further into this.... in your opinion, would those changes to my truck decrease my mileage by 6mpg? (Just seems alot)
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Nissan Frontier Forums : Problems / Technical
Topic: tiresome mileage chat SUDDEN DROP IN MPG
