Low Mpg?

[aamerh]

I checked my mileage last fill up and I'm only getting 15.8 mpg.

I've been driving with the AC on and off on some trips since its summer and hot in texas... and not driving too fast...

 

The air filter is relatively new, seafoamed it maybe 2 months ago, and regular oil changes.

The cars a 95 but should it be this low? Anything I could do to improve the mpg?

[enginph]

I checked my mileage last fill up and I'm only getting 15.8 mpg.

I've been driving with the AC on and off on some trips since its summer and hot in texas... and not driving too fast...

 

The air filter is relatively new, seafoamed it maybe 2 months ago, and regular oil changes.

The cars a 95 but should it be this low? Anything I could do to improve the mpg?

 

What kind of driving? What speed? How long?

 

[aamerh]

mostly city driving at 45 mph, maybe 1/4 of the miles were highway around 75 mph.

City driving is generally shorter trips less than 15 min long.

Driving style... um... not slow driving but I try to watch how fast I accelerate to get better mpg.

[Matt64341]

The biggest killer of gas mileage is braking. Every time you brake you take energy in motion and change it to heat which is useless. That is one of the reasons why city driving gas mileage is much worse than highway (the other is the speed). I notice a lot of people who feel like they have to have their foot on a pedal at all times, and it eats away at their gas mileage. If you go directly from the gas to the brake then you have made a mistake. There should always be a few seconds of coasting between unless you are avoiding a collision.

 

If I come to a big hill I will toss it into neutral to eliminate engine braking, and you gain energy from the downhill. In neutral you are using the same amount of gas it takes to idle the engine, but you are going at speed and accelerating. It is free energy and it should not be wasted.

 

I run about 38-39 psi in the tires to reduce rolling resistance, and I have a modified intake. If you purchase a chitown intake you would see a good jump in your gas mileage. Any maintenance like new sparkplugs, fuel filter and others will help. A bottle of Techron wouldn't hurt, but you did say you seafoamed, so you are probably fine.

 

I also very rarely use the AC. I am sure it is too hot in Texas to not use it, but if you use AC Econ, and set it to a temperature that is higher but still comfortable, maybe 80 or so. I am not sure exactly how the millenia AC is controlled, but it should be by thermostat, which would turn off the compressor when the cabin temperature is below the set temperature. If the compressor runs less then your gas mileage will benefit.

 

You should definitely be getting better than 15 mpg, I was very hard on my last tank of gas and got over 25 mpg. I have gotten 26.5 as my highest and I am expecting to beat that before the gas is switched to the winter mix. (a lot of my driving is rural 40 - 55 mph with a little traffic). You should be able to do a few things to get it up at least to 19-20 in the winter and 21-22 in the summer.

[aamerh]

wow thanks for writing all that up.

Yeah, I always keep the AC on econ when I do have to use it. Tires are a little lower than what you've got so I'll air those up and really try to max out this tank of gas and see where it gets me to.

[enginph]

If I come to a big hill I will toss it into neutral to eliminate engine braking, and you gain energy from the downhill. In neutral you are using the same amount of gas it takes to idle the engine, but you are going at speed and accelerating. It is free energy and it should not be wasted.

 

In neutral you will use same fuel as idle, but in drive throttle released, you will burn zero, requirement of an OBD car IIRC. Putting to N would hurt more. I try not to stop, when i see a red light ahead i apply brakes to slow down to 20-25 mph and cruise at that speed, no fuel. If i will wait at the red light for a long time then i put it to N, when stopped. I also manually turn AC off if i stop. With the wind, AC works more efficiently and i can bear the 1-2F temp increase when stopped. Above 50, AC consumes less fuel than windows down (wind resistance). At around 45mph your are in the ballpark of overdrive clutch engaged or not. If engaged, rev should be ~1800rpm. Try letting the throttle a little to have it engaged.

 

What engine, mileage? I drive 2.5 miles every day to work and back to home. Both from a cold start, couple hills and lights, speed limit is 50-55, so i accelerate to 60 and stop several times. Pretty bad driving for fuel economy and engine. Still, I can get aroung 20-21 repeatedly. 16 is a little low..

 

[ing-schu@online.no]

Saint, you beat me to it, putting it in neutral while coasting is not saving fuel and a bad idea anyway on an auto tranny I believe. Engaging the TCC (torque converter clutch) and trying to keep it engaged as much as possible is my trick for good milage, this works even in the city. I accelerate quite fast (1st and 2nd) up to 60 km/h where it engages in the 2,5, at 1500 rpm.

 

This procedure gives me a year round average of about 26mpg, and a best ever 33,1 mpg on a long trip, fully loaded. I have very little short trip driving though, driving 16 miles each way to work. And I use the block heater from september till may, or when morning temperature is sub 10 degrees C.

[Matt64341]

The reason I will use neutral is because if you are on a big downhill, and push it into neutral you instantly feel that you begin to accelerate faster. I have done a lot of test runs on hills starting at the same speed in D with no gas and in N with no gas and at the bottom of the hill I am traveling about 10% faster when in N. I notice the engine braking more in the millenia than in other cars though.

Another reason I think that it helps is there was a time where my coolant was leaking and I was overheating. (I never let it get too close to the top of the gauge before I turned it off) On the top of the hill I was getting close to pulling over to let it cool, but I put it in neutral instead and coasted down the hill. As I was coasting the temperature gauge fell all the way back down to operating temperature. When going downhill in drive the temperature didn't dip like it did in neutral. And if there is less heat than there should be more efficiency. Still, I don't have any way to prove if it makes a difference at the end of the tank though or if it is unhealthy for the transmission.

 

Some people have also been saying that accelerating extremely slowly and driving slow will improve gas mileage. But accelerating too slowly will actually hurt efficiency and will make everyone behind you angry, and driving slow for gas mileage is only true at a certain point. Your car is less efficient at 80 mph than 50 because of drag, but it is more efficient at 50 than it is at 30. So you would actually be better going 50 in a 40 than you would to go 35. So slower is not always better. I really believe that they should sell a cars with a mpg vs. speed graph to show how efficient certain speeds are. We would know our cars better and people could get a more efficient car to suit their needs.

 

To get the best gas mileage you need to cycle your speed a lot more, in a 40 at some points such as downhills you could be at 50-55 and at other points you could coasting down to 35 or 40 to take curves. On straightaways you can hold a steady 50. And at the end of the road you shouldn't need brakes until after you have coasted down to 15-20 mph. In the end your average speed on the road will still be about 40 or a little higher even though at one point you might have dipped to 35 and coasted all the way down to 20 at the end. The only thing that will prevent you from doing this in some cases are speed limits.

 

[///BHRpowered]

You should be getting alittle better BUT NOT MUCH MORE.

 

Xedos and MTS will quickly come along to say you should get almost 30 on the highway etc but its bullcrap. Even mazda claimed 22-28, which was before they were required to change it to actual driving conditions, In 8 years of ownership I'v never gotton either, usually I average out around 17 which was mostly city, doing straight highway to various MWM going through full tanks (though I admit to cruising at 70-80) I would get 22 MAX.

 

Some people claim running midgrade gets you better gas mileage, but its more then likely because of the all teh gunk, shit building up, and engine painfully running on 4 cylinders, and you'll know it.

 

Best thing I can recommend to you is only use the A/C when at speeds above 60, run synethetic fluids, clean air filter, 32psi front, 30psi rear, alinement, and an over looked area is if your brakes are getting old lubre the slide pins. A pad not fully retracting cna cause hell on mileage.

[aamerh]

It a 1995 with 165,000 miles on it now.

Whats the best way to engage the TCC?

[///BHRpowered]

The problem with speeds is there is no real answer, since every car has different gearing on grand cherokee's for example if you have a v8 or the hemi you get about 1.5-2mpg more when going between 60 and 68, but if you have a 6cyl you have a different tranny where overdrive engages sooner and going 50-55 is the best.

[latinopikachu]

you will feel the TCC engaging. try going exactly 50, 55, or 60, one of those. and then try to go 1-2mph more, you will feel it jiggle as it cant decide whether to have it on or off, and you will have your answer. since i always go 75+ i've forgotton

 

and as far as the temp gauge going up, teh car wouldnt do it running midgade, but I put super in by reflex and it started getting hot at long stoplights and traffic but will cool down when the AC realizes oh shit i should turn on or speed up the fan, and it'll pipe down. (YES coollant is FULL) i'll always put it into N going off the exit ramps to cool down the engine even more after highway runs. with AC econ it doesn't run the other fan or something because i notice a power loss and a tick higher temperature reading

 

 

[///BHRpowered]

Well then you have other issues.

 

My temp gauge never goes above 50%, usually rigt around 45% or so, this includes quite spirited driving sand climbing mountains.

[latinopikachu]

its not somtehing pressing, like the car will do it when you sit in the driveway for 30 seconds, no. after 10-15 minutes of sitting in traffic with the ac on, or stop and go, it will begin to heat up. do you have any idea where the damn coolant temperature sensor is??? buried under a bunch of shit , thats where

[///BHRpowered]

MWM07, I sat in traffic for over an hour going no faster then 10mph, usually stop and go, with a/c on at around 74ish....all because some god damn jackass decided friday afternoon would be a great time to pave and shutdown all but 1 lane of the highway...damn you md

[Matt64341]

I have never seen the temp rise except for the time when the coolant was leaking, but I don't live in as hot of a climate and I almost never sit in traffic. I think AC econ is just turns off the compressor more often.

 

[///BHRpowered]

I'v (sadly) driven my millenia in up to 105 degrees, no difference.

 

Granted I have always had the coolant changed every other year and wetter water added

[aamerh]

Thanks for all the comments.

I'll try messing with TCC tomorrow.

[enginph]

When TCC engaged, at 2k rpm your speed is 54 mph with 17/215/50 tires.

 

[ing-schu@online.no]

I guess you have to drive your car to experience real life milage. I like to keep track of it, therefore I keep a book in the car where I notice date, milage and litres filled on every tankfill. I've put 116k km on it now, divided on say 600km average on each tank of gas, equals 193 times of filling her up. I would say I keep pretty good track of my milage. Last time I calculated average it was 25,4 mpg. My worst ever was 22,5 during towing. Like MTS will confirm, 30 mpg is easy if you know how to drive remotely economically and the car is in proper condition. Conditions: No AC, windows shut, no cruice control and sub 65 mph. And of course, trying to keep the TCC engaged as much as possible. That is the sole most important thing. Actually this gave me 33,1 once. No kidding. And my average includes all the towing and sprited driving I've enjoyed too. I rev to 5k on a daily basis. Only now I've finally got myself a new daily driver

[latinopikachu]

you will explain immediately

[ing-schu@online.no]

A thread is coming up It is not quite up to X-man standards yet, be patient. I can confirm it was built in Hiroshima, probably late 2003

[///BHRpowered]

No AC, windows shut, no cruice control and sub 65 mph.

 

Cruise control off fine, but slow, windows up, bah takes all the fun out of it

[latinopikachu]

[enginph]

A thread is coming up It is not quite up to X-man standards yet, be patient. I can confirm it was built in Hiroshima, probably late 2003

 

I can think of 6 or rx.