Really poor MPG... what should I replace?
06-18-16, 04:37 PM
#31
Before I start, I realize this is not a Prius. But I've owned an 08 USB ISF prior to this that regularly got 17 city/25 hwy MPG . Right now my 2011 ISF with ISSForged QED is getting 12 city/22 hwy on average.
I thought that it might be due to my right foot from wanting to hear the exhaust roar, but even when I am careful I can only manage 14 mpg combined at best. I checked my tire pressures to make sure they're at the factory spec so I don't think underinflation is causing my poor mileage.
I also had a CEL for bad O2 downstream sensors. I replaced them with new Denso units and cleared the CEL and it hasn't come back. My MPG has stayed the same though. No other CEL's.
What else could I change/check to make sure my car's engine is running as efficiently as possible? Air filter? Spark plugs? Should I run fuel injector cleaner at my next fill up?
Anyone else get really sub-par MPG even for an ISF? I feel like I'm getting as bad mileage as my friend's old C63 which has an even bigger engine than ours.
I thought that it might be due to my right foot from wanting to hear the exhaust roar, but even when I am careful I can only manage 14 mpg combined at best. I checked my tire pressures to make sure they're at the factory spec so I don't think underinflation is causing my poor mileage.
I also had a CEL for bad O2 downstream sensors. I replaced them with new Denso units and cleared the CEL and it hasn't come back. My MPG has stayed the same though. No other CEL's.
What else could I change/check to make sure my car's engine is running as efficiently as possible? Air filter? Spark plugs? Should I run fuel injector cleaner at my next fill up?
Anyone else get really sub-par MPG even for an ISF? I feel like I'm getting as bad mileage as my friend's old C63 which has an even bigger engine than ours.
06-18-16, 04:45 PM
#32
Pole Position
Gotta agree^^^^^^^I romp on my car pretty hard and I average at least 17-20ish every tank?? Something doesn't seem right with that mileage, like someone else said earlier that's like C63 fuel mileage!
06-19-16, 03:03 AM
#34
Regarding summer and winter blends:
http://www.eia.gov/todayinenergy/detail.cfm?id=11031
Check tire pressure as others have said. If you can check timing like with an OBD logger you might be able to correlate intake air temperatures with timing adjust,nets. With 91 octane there's not much room for error when temperatures rise and if the car is detecting knock at all it will pull timing and add fuel to the mixture. I can tell drastic differences in performance from a 70° day to a 90° day and my fuel economy sucks.
I have a feeling that the government is getting it wrong regarding newer cars and fuel combinations requirements for summer and winter. I get much better gas mileage in the winter and the opposite should be true because you're pulling in less dense air in the summer than in the winter and if the computer is adjusting correctly you should be getting better fuel mileage in the summer, not the winter. That's just my observation though. The regulations, as in everything the federal government does, tries to make all things equal all the time and that's just not the case. We're not one giant nameless faceless blob of people all driving one type of vehicle in the exact same manner.
Last edited by Bigjon3475; 06-19-16 at 03:13 AM.
06-19-16, 08:27 AM
#35
Lexus Fanatic
" When you hear hoof steps, think horses not zebras". Look for the more obvious reasons first is all Im saying . Tire pressure, temps, AC operation , and a heavy foot are more than likely.
06-19-16, 09:42 PM
#37
Low Rolling Resistance Tires,
Increase your tire PSI (worse ride quality by a bit, also only wears the middle but its can be dramatic of an increase),
Feather your gas as much as you can
Drive in snowmode and allow for the gradual increase of speed, works as the same concept as throttle controllers by retarding the throttle response
Increase your tire PSI (worse ride quality by a bit, also only wears the middle but its can be dramatic of an increase),
Feather your gas as much as you can
Drive in snowmode and allow for the gradual increase of speed, works as the same concept as throttle controllers by retarding the throttle response
06-20-16, 01:07 AM
#39
This is the only acceptable time when MPG is that low. Even though we didn't get these cars for good gas economy, it's still relatively decent on gas. Jeff is just highlighting the fact that the car is that fun to drive and there isn't a need to really worry too much about it. Just enjoy the car and, presuming nothing is wrong with it mechanically or electrically, all should still point to a smile on your face when you drive it.
06-20-16, 09:54 AM
#41
I don't think anybody here is arguing about how to make the ISF more economical on gas, obvious a few owners(myself included) are suffering from some issue, when you drive half *** on the throttle on a full tank of gas and still get 13.9 mpg, while everyone else that drives city along with spirited driving gets +18mpg. My tire pressure is not low, and I still get very poor mpg. 13mpg is what I also get on my MKIV Supra, which has more power than the F, is modified and I'm in 'spirited driving' mode.
Last edited by Fsport2UR; 06-20-16 at 09:57 AM.
06-21-16, 03:41 PM
#42
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Definitely Tire Pressure is the most unchecked car maintenance item..
Needs to be checked / set once a month.. Driving in LA, I see people driving on half inflated tires all the time.
Also, you can reset your ECU by pulling the correct fuses.. This will erase the Long Term & Short Term fuel trims logs.
You can even erase and reset to ZERO both Fuel AVG indicators.
Last but not least, change the Engine Air Filter if it's old & dirty
Joe Z
Needs to be checked / set once a month.. Driving in LA, I see people driving on half inflated tires all the time.
Also, you can reset your ECU by pulling the correct fuses.. This will erase the Long Term & Short Term fuel trims logs.
You can even erase and reset to ZERO both Fuel AVG indicators.
Last but not least, change the Engine Air Filter if it's old & dirty
Joe Z
06-21-16, 05:24 PM
#43
Lexus Champion
and the funny thing to me is every time I go to the dealer I have to specifically tell them NOT to mess with my tire pressure.. door says 36 psi COLD. I drive to the dealer which is 30+ miles.. my tires are NOT COLD.
yet the idiots deflate them to 36PSI and the next morning after sitting on a cold cement garage floor the TPMS reads 31-32psi. and I lose 1-2mpg as a result of some idiot tech that doesn't understand the concept of cold vs. hot tires.
At road temp my TPMS typically shows 40-41 psi and with this heat wave we have right now it is showing as high as 43 psi after a 30-40 mile drive.
I've been fighting with dealers on this (GM, Chrysler, Toyota, and now Lexus) for 12 years since CAFE made it a requirement for them to check and inflate /deflate to the "CAFE Ideal PSI".
it got so bad with GM I was forced to install locking valve caps to keep them from deflating my tires.
06-21-16, 07:45 PM
#44
Lexus Fanatic
I know all about it
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