HI im new here and this is my first time posting. I have a prelude that gets very very very bad mileage. About 12-14 mpg in the last tank i used. Anyone know how to improve my mpg? i had all my fluids replaced as well as my air filter and i had my spark plugs replaced. i dont have anything to weigh down the car and i shift at 3000rpm. I just re-infalted my tires (all of which were under inflated at about 19-20 PSI) and right now i have a full tank of gas and i am trying to find out how many mpg i get now that i re-inflated my tires. ANYONE know what else i can do to improve my mpg?

 

Do a complete tune up. Do you drive with windows down because that lowers mpg also, but will not greatly affect it


Modified by lude98SH at 1:07 PM 12/27/2005

 

Look slike you checked most of the parts that could affect MPG.

Do you know if your O2 sensor is fine?

Other than that, I can't think of why you would get such poor gas mileage. Other than that, I would think there is something internally wrong, like a bent valve or something. But that is only worst case scenario. If your car is performing fine, then the engine is probably running fine.

Not sure what else ot suggest.

 

not throwing any cels?

 

Dont the fuel filter, distributor cap and rotor and ignition wires all affect performance and mpg?

 

They all do, if one or many is not working proper it could cause bad gas mileage. Also do a compression test that will tell if you have a bent valve or something like that, that would definatly hose your mileage. I usually run the fuel system cleaner every few months just to make sure nothing gets gunked up with my injectors. Check the basics first, change your plugs/wires, check o2 sensor, check to see if air filter needs changing, check your compression.

good luck.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by lude98SH &raquo;</TD></TR><TR><TD CLASS="quote">Do a complete tune up. Do you drive with windows down because that lowers mpg also, but will not greatly affect it


Modified by lude98SH at 1:07 PM 12/27/2005</TD></TR></TABLE>

No, i dont drive with my windows down, but i do use my heater from time to time in the early morning hours becuase i need to use my defroster. Could cold weather be a problem?

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by AndyD &raquo;</TD></TR><TR><TD CLASS="quote">Look slike you checked most of the parts that could affect MPG.

Do you know if your O2 sensor is fine?

Other than that, I can't think of why you would get such poor gas mileage. Other than that, I would think there is something internally wrong, like a bent valve or something. But that is only worst case scenario. If your car is performing fine, then the engine is probably running fine.

Not sure what else ot suggest.</TD></TR></TABLE>

I dont know if my O2 sensor is fine or not. I dont even know where it is (just got the lude for like 3 weeks) Could you guide me in how to find my o2 senor and tell me how to tell whether it is still good or bad?

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Chuckles99SH &raquo;</TD></TR><TR><TD CLASS="quote">They all do, if one or many is not working proper it could cause bad gas mileage. Also do a compression test that will tell if you have a bent valve or something like that, that would definatly hose your mileage. I usually run the fuel system cleaner every few months just to make sure nothing gets gunked up with my injectors. Check the basics first, change your plugs/wires, check o2 sensor, check to see if air filter needs changing, check your compression.

good luck.
</TD></TR></TABLE>

How do i a compression test?

 

just one thought on the weather idea, if you let your car warm up for a long time i.e: 20-30 min before you drive, you are wasting gas, other than that, just check what everyone else said, caus most of us with h motors that shift in the 5k range still get about 28-30 mpg hwy mileage from what ive seen

 

ignition timing

i know if i advance my timing slightly...i get lower mpg

 

yea..if this is a 5th gen you cant mess with timing

 

Gas is formulated differently from season to season. Obviously in the winter, the actual tempeture of the fuel in our tanks is very cold, (atleast it is where i live) this reduces the volitility of the fuel especialy on cold starts. So to be able to have decent cold start in the winter, the fuel has to be very volitile. This then affects the car at operating tempeture. Since the fuel is more volitile, it will pre ignite easier if there is a hot spot in the combustion chamber. This isnt a problem to the majority of the community, because their stock cars arent running that close to the edge of pre ignition and detonation. They can go through fuel changes without it effecting them too bad. Many cars are higher compression or use turbos/superchargers/nitrous which greatly increase cylinder pressure and the chance of pre ignition or detonation. Our cars will be much more touchy to different fuel volitilities. And if you are running a setup like this without anyway to tune for the changes in fuel, it will definatly cause some issues in the winter time. The gas which changes least over seasons is sunoco 94 and amoco 93.

Im not sure overall how that affects milage per gallon but definitly affects performance