mikeysentra Posted November 24, 2007 Share Posted November 24, 2007 My 97 pathy has been doing ok with fuel mileage untel recently when it got below 30 degrees. I had been averageing about 15.5-16.5 all summer and then all of a sudden over the course of 3 tanks of fuel It has dropped to about 12-13 MPG. Is this normal for a pathy in cold weather? or are my O2 Sensors starting to get lazy and run rich? I run mostly freeway miles @ 70 MPH. and nothing has changed in my driving style. BTW Its a 97, 134,000 miles with a K&N air filter, 2.25 exhaust from the y back and 31x 10.50 15's on stock wheels. and yes I have cleaned the MAS and about 4,000 miles ago a complete tune up with Fuel filter, NGK plugs and wires and a factory cap and rotor. I just want to know if this is normal or if there is somthing wrong that I need to get fixed. Thanks in advance Link to comment Share on other sites More sharing options...
Orangetang Posted November 24, 2007 Share Posted November 24, 2007 I think the combination of large tires and cold weather is hindering your economy. Cold air is dense and requires more fuel per unit, thus burning slightly more fuel. The plus side is you're probably making more power. I'm getting 15-17mpg (VQ) on the highway in this cold weather, and closer to 18-20mpg in the summer. Take into account the % difference between your factory and current tire diameter, when calculating your economy. Your odometer is probably out by about 5%. Someone else can probably explain how the engine determines air density/temperature and fuel injection far better than myself, so I won't bother. Seems last time we had this discussion there was a lot of debate, especially with octane and economy. Link to comment Share on other sites More sharing options...
nissandoms47 Posted November 24, 2007 Share Posted November 24, 2007 Probably oxygenated gas or whatever they do to gas during the winter. Link to comment Share on other sites More sharing options...
Orangetang Posted November 25, 2007 Share Posted November 25, 2007 I've never heard of such a thing. Link to comment Share on other sites More sharing options...
vengeful Posted November 25, 2007 Share Posted November 25, 2007 There are 3 reasons for your diminished fuel economy, other than your larger tires. 1.) Oxygenated Fuel. It doesn't burn as efficiently as pure fuel. It is oxygenated to prevent freezing in sub-freezing temperatures. The Oxygenation process helps to reduce/eliminate water molecules in the gasoline. However, you also get less gasoline per gallon of oxygenated fuel than you do with pure fuel. 2.) Your engine runs in Closed Loop for longer while it is taking longer to warm up. Since the cold air temperatures keep the engine cooler for longer, it runs in Closed Loop for a longer period of time, which uses more gas than Open Loop, because none of the sensors are activated and the ECM is controlling the vehicle based on pre-programmed algorithms, instead of sensor given data for optimum efficiency and performance. 3.) Colder Air is denser than warmer air. This is a double edged sword though, as you gain a bit of power, but lose a bit of fuel economy as a tradeoff. Denser air requires more fuel per volume unit than less dense air, as air is injected based on weight. I also notice a significant decrease in winter fuel economy, it's normal. Link to comment Share on other sites More sharing options...
Trainman Posted November 25, 2007 Share Posted November 25, 2007 Probably oxygenated gas or whatever they do to gas during the winter. I've never heard of such a thing. Yup, get it here in the winter. We all know when the "winter" gas comes into town, our fuel consumption goes up. Probably depends on what part of the country you are in, I doubt that the "winter" gas in Vancouver or Victoria is as oxygenated as it is here in the interior. Just a thought anyway. Link to comment Share on other sites More sharing options...
mikeysentra Posted November 25, 2007 Author Share Posted November 25, 2007 There are 3 reasons for your diminished fuel economy, other than your larger tires. 1.) Oxygenated Fuel. It doesn't burn as efficiently as pure fuel. It is oxygenated to prevent freezing in sub-freezing temperatures. The Oxygenation process helps to reduce/eliminate water molecules in the gasoline. However, you also get less gasoline per gallon of oxygenated fuel than you do with pure fuel. 2.) Your engine runs in Closed Loop for longer while it is taking longer to warm up. Since the cold air temperatures keep the engine cooler for longer, it runs in Closed Loop for a longer period of time, which uses more gas than Open Loop, because none of the sensors are activated and the ECM is controlling the vehicle based on pre-programmed algorithms, instead of sensor given data for optimum efficiency and performance. 3.) Colder Air is denser than warmer air. This is a double edged sword though, as you gain a bit of power, but lose a bit of fuel economy as a tradeoff. Denser air requires more fuel per volume unit than less dense air, as air is injected based on weight. I also notice a significant decrease in winter fuel economy, it's normal. Thanks for all the input. I was thinking that it had a effect because of longer warm up and Oxegenated fuel but wanted to make sure. thanks everybody for the input. Link to comment Share on other sites More sharing options...
XPLORx4 Posted November 25, 2007 Share Posted November 25, 2007 (edited) Your engine runs in Closed Loop for longer while it is taking longer to warm up. Since the cold air temperatures keep the engine cooler for longer, it runs in Closed Loop for a longer period of time, which uses more gas than Open Loop, because none of the sensors are activated and the ECM is controlling the vehicle based on pre-programmed algorithms, instead of sensor given data for optimum efficiency and performance. Dan, just FYI, what you just described is "Open Loop" operation. "Closed Loop" refers to the PCM adjusting A/F ratios based on feedback from the O2 sensors: O2 sensor feedback -> A/F ratio adjustment -> O2 sensor feedback -> A/F ratio adjustment (i.e. the feedback loop is closed). The PCM won't let the engine enter closed loop until the coolant temperature is 154°F. Edited November 25, 2007 by XPLORx4 Link to comment Share on other sites More sharing options...
Plus Posted November 25, 2007 Share Posted November 25, 2007 My 97 pathy has been doing ok with fuel mileage untel recently when it got below 30 degrees. I had been averageing about 15.5-16.5 all summer and then all of a sudden over the course of 3 tanks of fuel It has dropped to about 12-13 MPG. Is this normal for a pathy in cold weather? or are my O2 Sensors starting to get lazy and run rich? I run mostly freeway miles @ 70 MPH. and nothing has changed in my driving style. BTW Its a 97, 134,000 miles with a K&N air filter, 2.25 exhaust from the y back and 31x 10.50 15's on stock wheels. and yes I have cleaned the MAS and about 4,000 miles ago a complete tune up with Fuel filter, NGK plugs and wires and a factory cap and rotor. I just want to know if this is normal or if there is somthing wrong that I need to get fixed. Thanks in advance I noticed the same thing with my pathy. Engine light has come on (i'm at 187 500), and i know its the o2 sensor, so i thought it just might be that, but usually you can smell if it is burning a bit rich. So i'm going to have to say its the cold weather. Link to comment Share on other sites More sharing options...
Pezzy Posted November 25, 2007 Share Posted November 25, 2007 10-4 on the cold weather. Mine went from about 420+km/tank to 375ish with the change in temps. Sucktactular! Link to comment Share on other sites More sharing options...
adamzan Posted November 26, 2007 Share Posted November 26, 2007 I can get 600kms out of a tank normally, now its down to 550 in my dads r50, he said when he was driving my wd21 that it was slightly better on gas Oh and pezzy, that milage really must drain the bank account....but i guess the weight from the mods and what not is the cause of that? Link to comment Share on other sites More sharing options...
Pezzy Posted November 26, 2007 Share Posted November 26, 2007 yup... plus I really needed an alignment... will be interesting to see what I get now... had the truck aligned a few days ago. Link to comment Share on other sites More sharing options...
94extreme Posted November 26, 2007 Share Posted November 26, 2007 There are 3 reasons for your diminished fuel economy, other than your larger tires. 1.) Oxygenated Fuel. It doesn't burn as efficiently as pure fuel. It is oxygenated to prevent freezing in sub-freezing temperatures. The Oxygenation process helps to reduce/eliminate water molecules in the gasoline. However, you also get less gasoline per gallon of oxygenated fuel than you do with pure fuel. 10% ethanol also eats into the MPGs Link to comment Share on other sites More sharing options...
Orangetang Posted November 26, 2007 Share Posted November 26, 2007 Anyone planning on installing a larger fuel tank? 100L+ would be nice. I'll probably do more camping next summer than I did this year, and too many times I found myself relying on the lil' red fuel containers to get me back to civilization. Link to comment Share on other sites More sharing options...
94extreme Posted November 26, 2007 Share Posted November 26, 2007 there really isn't much more room back there.. i still wouldn't mind having an NG setup for the extra range but that's kind of a pita to get here in the states. Link to comment Share on other sites More sharing options...
02silverpathy Posted November 26, 2007 Share Posted November 26, 2007 (edited) Is it time to talk about Toulene? Mixed in at about 7-10% solution?? Yea yea crazy me...I proved that at 1-1.25 ounce per 10 gallons of fuel that the path added nearly 2mpgs, thats all well and good. I have been reading more about Toulene. This is a fuel that by itself yields a 120 octane (RON method). It can be safely mixed at about 1 gallon per 20 in most all high compression engines (so I have read) this makes your 92 octane about 93.6...some Corvette owners like to use much larger quantities to achieve 103-104 octane...but that is a little too risky for me and I love my 3.5 so no thanks!! Obviously rasing octane is good for many high compression engines...but also makes higher temps throughout...thus moving up the scale by 10-15 points from 92 or 93 to 93-94 would be sufficient....especially during "Winter Gas"months! This week I re-attached my throttle body coolant lines and noticed an improvement in MPG already...please keep in mind I fall into the extreme driving conditions category...I live less than 3 miles from my job and only average 210 miles in 10 days and thus only about the same per tank!! Edited November 26, 2007 by 02silverpathy Link to comment Share on other sites More sharing options...
mikeysentra Posted November 27, 2007 Author Share Posted November 27, 2007 Well after taking my Yakima basket off the pathy and the bug deflector I averaged 13.5 MPG with this last fill up. About a 1 MPG improvement over having the accessorys on the vehicle. I will say that its alot quieter also. no more wind noise. Now its about to snow in my neck of the woods so It will probably go back down when I lock the warn front hubs so I can use the 4 wheel drive. Link to comment Share on other sites More sharing options...
Plus Posted November 27, 2007 Share Posted November 27, 2007 10-4 on the cold weather. Mine went from about 420+km/tank to 375ish with the change in temps. Sucktactular! haha, don't worry i'm only at 350-60 with change, and thats when i'm trying to conserve gas. Do higher octane gases burn faster or would that make a difference? Link to comment Share on other sites More sharing options...
navygz19 Posted November 27, 2007 Share Posted November 27, 2007 10% ethanol also eats into the MPGs See, we've been using E 10 for the better part of a year now and I never noticed any sort of MPG reduction. Oh late, however, it' a different story...probably close to 14 MPG or so, down from about 16. Yikes...and the price of a gallon keeps going up! Link to comment Share on other sites More sharing options...
CALPATHY Posted December 3, 2007 Share Posted December 3, 2007 I don't feel so bad now, compare to some of you. When I first got my Pathy, I was getting 16-18 MPG (with manual tranny). After I installed Warner hubs, it jumped up to 16 in the city to 20+ on the highway. Last month or so I've only been getting 19 to 19.5. It must be the oxygenated gas. Link to comment Share on other sites More sharing options...
csutke Posted December 3, 2007 Share Posted December 3, 2007 dont want to hear bout it I was getting around 14 city/highway now im down to 11 so all yall that are getting 15+ can go suck a big one J/K (sorry for the rant but seriously come on) Link to comment Share on other sites More sharing options...
02silverpathy Posted December 3, 2007 Share Posted December 3, 2007 csutke....I'm with you man! I get 13 city...hwy is always like 20-21, TB coolant lines heating up the TB or not. It doesn't seem to matter if I drive fast or slow, city is 13!!! Link to comment Share on other sites More sharing options...
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