Decrease in Gas Milage Problems

The opposite, more dense gas means it has less air in it, so you'd need more air to get the same air/fuel ratio...

 

http://www.tacomaworld.com/forum/1st-gen-tacomas/171676-1st-gen-fuel-filter-how.html#post3572016 Make sure you have a short-handled rachet.

 

good job!

 

put a bottle of Gumout in there and fill it with 87 or 91 for a tank or too. Helped me. But i second a lot of the guys with winter being the same time i started getting bad gas mileage

 

Gas price is government regulated here so its the same price at every station. People just learned from experience what stations have lower quality fuel.

 

I am having problems with gas as well.

2005 V6 60kmiles, I measure nearly every tank. I am now getting 14.5-15mpg.... I never got the before. I never got below 16.5mpg...... I use gas from 10 states, as I travel. Its not winter gas...its been doing it since summmer...There is something going on, not sure yet...

I changed spark plugs, cleaned filter KN.. I was using to much oil on filter and my MAF trt body was gunked. I cleaned each...still bad mpg.
I have used super, reg, added gas crap to tank...still nothing....

She runs perfect.....but the gas mileage.... I am going to try a CAT cleaner, then try new MAF..

It has no check engine light and I have had it tested 2 x at auto store....

I will find it, will just take time, or the check light will come to lite! soon...I really hope...damn it its killing me
I

 

Alright, I've changed the fuel filter, cleaned the MAF sensor, and topped off all the fluids. My MPG's are still crap. Any more suggestions? The truck is running perfectly but I'm beginning to think that it might be something to do with the ECU; running rich and such. Usually the check engine light would come on for that. I'm going to reset the ECU one more time and see what that will do. Any other suggestions?

 

"RVP" mixed gas-Validated by a friend in Gas refining industry.... There is a difference in winter/summer gas....And also some cities, due to smog regulations, could have there own formulated blend.

How ever, my decrease in MPG is based over 7 years of driving my truck....and something is wrong...I will find it or I will be driving a 3/4 ton truck full size with room to move and tow, and with better MPG...


Reid Vapor Pressure
From Wikipedia, the free encyclopedia
Reid vapor pressure (RVP) is a common measure of the volatility of gasoline. It is defined as the absolute vapor pressure exerted by a liquid at 100 °F (37.8 °C) as determined by the test method ASTM-D-323. The test method applies to volatile crude oil and volatile nonviscous petroleum liquids, except liquified petroleum gases.
The matter of vapor pressure is important relating to the function and operation of gasoline powered, especially carbureted, vehicles. High levels of vaporization are desirable for winter starting and operation and lower levels are desirable in avoiding vapor lock during summer heat. Fuel cannot be pumped when there is vapor in the fuel line (summer) and winter starting will be more difficult when liquid gasoline in the combustion chambers has not vaporized. Thus, oil refineries manipulate the Reid Vapor Pressure seasonally specifically to maintain gasoline engine reliability.
The Reid vapor pressure (RVP) differs slightly from the true vapor pressure (TVP) of a liquid due to small sample vaporization and the presence of water vapor and air in the confined space of the test equipment. That is, the RVP is the absolute vapor pressure and the TVP is the partial vapor pressure. Conversion between the two measures can be found here, from p. 7.1-54 onwards.

 

Smell your exhaust fumes. If it is rich you can tell by pungent smell. Try chevron techron fuel system cleaner. Your truck is old..probably has blowby. But mpg should not decrease crazy.

 

On the O2 sensor topic. My ride: 97 2.7L 4x4 Auto

The local Toyota dealer lists the sensors as different part numbers, priced differently.The Toyota Service Manual only lists different resistance values: Bank 1 Sensor 1: 5- 7 Ohms, Bank 1 Sensor 2: 11 - 16 Ohms.

The OEM (DENSO) lists them as the same part number for front and rear. E-mailed them about it and got no response. Are they the same unit or different?

Gas mileage has been bad lately (12 mpg city, with the understaning that MN runs a heavy winter blend). Did plugs, wires, air filter, fuel filter, themostat/coolant and it went to 14 mpg city. O2 sensors are original with 85,000 miles on them and probably should be replaced. Still need the clean the MAF.

Was going to order O2 sensors from Rock Auto (they list the front and rear as the same unit) but was wondering if anyone knew for sure?

 

Where is the fuel filter located? I haven't replaced the f.filter on my 95 tacoma yet, but have had it in mind. I got poor mileage friday and the check engine lite came on. I hooked it up to a diagnostic obd2 reader and got the code: P0170. Where's the o2 sensor?

 

MPG's are back to normal now. I replaced the fuel filter and tuned all of the lines/belts, reset the ECU and now everything seems to be working out. I put a new set of back tires on as well and averaged 25 MPG @65mph on the highway down to the beach. The deckplate mod is worth it, just takes some toying with the ECU to induce more air and not fuel into the system

 

I know what the problem was