mileage issue
- Thread starter 01thunder
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When it comes to MPG I don't know if there is anything real fancy you can do.
What comes to mind first is - Tire pressure, Driving habits, Spark Plugs and wires, Clean MAF, Clean Throttle body, Possible O2 Sensor aka Air/Fuel sensor depending on your year.
I also just noticed that you're not running a stock wheel setup. I'm not sure if you're calculating in the difference. I'm not too fond with how that works, and if your situation would make any substantial difference. Hopefully I didn't offend you with such a basic answer, just wanted to chime in and help with what I can.
I am new around here and might be missing something very obvious, but this should at least give a decent idea of where to start.
Matt
What comes to mind first is - Tire pressure, Driving habits, Spark Plugs and wires, Clean MAF, Clean Throttle body, Possible O2 Sensor aka Air/Fuel sensor depending on your year.
I also just noticed that you're not running a stock wheel setup. I'm not sure if you're calculating in the difference. I'm not too fond with how that works, and if your situation would make any substantial difference. Hopefully I didn't offend you with such a basic answer, just wanted to chime in and help with what I can.
I am new around here and might be missing something very obvious, but this should at least give a decent idea of where to start.
Matt
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ShooterMcGavin
New member
Everything that Grassfed suggests above is good advice. a couple more things to check or replace are fuel filter, air filter, and PCV valve. Possibly alignment too? I'm reaching here.
A.Wilson013
New member
There are people that claim some nutty numbers on here, that's for sure.
However, I promise you that on a drive I did last week (all highway 60-70mph) I got 16.5mpg one way with the AC on (defrost) and 18.92 mpg on the way back (all highway, 60-70mph). The ONLY change was that I turned the defrost off. Keep in mind that's with supercharger, lift, 5x 33" tires, skids, bumpers, etc. etc. Since then I have only turned my defrost on for a few minutes when I start it up and have been averaging 16.8mpg around town. Up from about 15.
What are the conditions you're driving in? Traffic? Commuting through town to work? AC on? With any of that I'll say 15+ is kinda low, but not too bad.
If you're pulling 15+ on the freeway w/ no traffic something is not right for sure. Brakes dragging? o2 sensor being wonky? Do you have a scan tool? What are your fuel trims at while you're crusing around?
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01thunder
New member
commute to work, pick up son at school, etc. no AC. highway it's a bit better, close to 16-16+. truck is pretty stock. O2's are fine, in fact, everything is fine, for the most part. no stalling, no engine light on, etc. brakes aren't dragging.
ShooterMcGavin
New member
I think the service reqs for our trucks say that the fuel filter is a lifetime part. It's not. Even though your maintenance is up to date, have you changed that in the last 30k miles? Could make a noticeable difference.
THays
New member
I'm having similar issues with my 99. Average MPG was probably 15 city, 18 hwy but in the last few months it had tanked to around 12 city. Being in Iowa, I am attributing some of that drop off to driving in 4wd more, letting my car "warm up" and the winter gas blend.
Just replaced plugs, air filter and did valve cover gaskets so hoping for some improvement.
Just replaced plugs, air filter and did valve cover gaskets so hoping for some improvement.
MStudt
official vendor
I average around 16.6-16.8 with the occasional 17.5 MPG on the highway. I have an Ultra Gauge that tells me my average MPG is 16.8 with 285/75/16 tires. Cold weather will also cause for a lower MPG if you're in a colder state. I notice my MPG's drop from December through the end of February every year.
When I first bought mine, all stock, I drove 2 hours 100% highway and it got 14.5mpg! No check engine. I cleaned everything, replaced plugs, wires, fuel filter and did another trip and got 19.5. Both times on cruise @70mph solid. The second trip had 5-10% city too so I'd've done even better just highway. Don't be discouraged.
As people said. Some parts may seem "fine" like fuel filter and oxygen sensors but they should be replaced at intervals, especially if showing bad mpg. I also had one size bigger tires on the second trip.
Good luck.
In the city, I'm lucky to see 15.5 though
As people said. Some parts may seem "fine" like fuel filter and oxygen sensors but they should be replaced at intervals, especially if showing bad mpg. I also had one size bigger tires on the second trip.
Good luck.
In the city, I'm lucky to see 15.5 though
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diverscale
Member
How do you know youe o2's are fine? You can have lazy o2's without a check engine. You would have to scan the voltages of yours before you net them out of your problem
mtbtim
Elite Member
On my 2000 SR5, I've done all the suggested items like replacing A/F and O2 sensors, plugs and wires, PCV Valve, Fuel Filter, Cleaned Throttle Body and MAF Sensor. I can get up to 21 mpg on the highway if I'm driving mellow and not loaded down with gear. If I'm carrying a lot of weight and/or driving a lot of hills, the mileage goes down to 18-19. I rarely drive a tank of gas with just city driving, but I know the mileage drops big time down to around 15-16.
diverscale
Member
I easily get 21 MPG at 75MPH on highway too. O2 sensors are not lifetime items. They last 200-300 K KM maximum at full efficiency.
