new 94' VX owner, several "advanced" questions!!! lol...

[1993CivicVX]

Originally Posted by mnstrvx

Hi everyone,

I don't know how some of you folks are getting incredibly high MPG figures? I went through a tank of gas already, but for a good duration of time the car was idling as i was "diagnosing" things under the hood (also changed fuel filter and spilled some fuel). not to mention the fact that the tire pressure was incredibly low. I still got about 420 miles to the tank (I was kind of disappointed). this was all primarily city driving. I was doing a lot of above 2,000-2,500rpm shifting (until i read some more threads regarding shift points).

so, any advice would be greatly appreciated? I would love to see ABOVE 50mpg (500+ per tank full).

Okay... you do know that your tank is 10.0 gallons, right? So 420 miles on a tank (how many gallons did you fill up with? Probably less than 10) is probably mid 40s. It's very easy to get good gas mileage in the VX. You don't have to do anything too fancy and there are some key things you should know.

0. The more you brake, the more fuel you use. Try to drive in such a manner to avoid slowing the car down more than necessary. Fuel saving is all about conservation of forward momentum. Roll baby roll! (Coasting in gear is less efficient than coasting in neutral. Leave it in gear if you are coming to as top.)

1. When the engine is cold, the VX gets piss poor gas mileage. If you are doing lots of short trips and you're not seeing the temp needle get close to the little thermometer picture thing then you're never going into lean burn and are generally using lots of fuel.

2. Once the engine is warmed up (the temp gauge needle is just below the temp picture) accelerate slowly and shift at RPMs that will have you pulling from 1000 or 1050rpms after you have shifted. No reason to shift at higher RPMs, unless going up hills.
On flat here are my shift points:
1st and 2nd gear @ 1500rpm
3rd and 4th gear @ 1200rpm
5th gear @ 1100rpm.

3. Don't drive over 65mph. Speeds between 30mph and 55mph in 5th gear will get you the best mpg.

If you follow the above points while accelerating with a feather foot you will have mid 50s or I'm a Scottish terrier (unless you do lots of short trips and lots of city driving). The VX does not shine in the city, unless you learn some more advanced techniques.

Okay, on to more advanced and high falutin' feats of fuel savings beyond feather footing for when you are doing lots of short trips with cold starts and/or city driving.

The first five minutes your engine is warming up uses tons of fuel. One way I fight this is by employing the tried and true technique of pulse and glide (tried and true at least for this car). I'll get up to slightly higher than my desired speed and then turn my car off and coast for awhile, then I'll bump start the car and repeat the process. I'll do this until my temp is up, at which point, if your car is running right and your head lights and A/C aren't on, you should idle at 500rpm in neutral negating the need for turning your engine off and coasting to save fuel. Coasting in neutral when the car is warm is an easy way to save fuel.

In the film Wall-E there is a scene that makes a very nice and simple analogy of pulse and glide. Wall-E is in outer space holding onto a Fire Extinguisher. He fires the extinguisher to propel himself forward.. then glides for awhile.. and then repeats to propel himself forward again. Same principle on the road.

To save fuel while the engine is cold employ the pulse and glide method:
Accelerate in the highest gear possible to just above your desired speed, then put in the clutch, wait a half a second or so, kill the engine, wait another half a second, turn it back to ON position (leaving the engine off) and coast in neutral for as long as prevailing traffic and your patience will allow. Then bump start it. You should avoid bump starting in 2nd gear, and definitely not in 1st gear! There are certain speeds that correspond to certain gears you should bump start in.

Speeds that correspond to the appropriate gear to bump start in:

5th gear; any speed above 13mph.
4th gear; between 9 and 13mph.
3rd gear; between 4 and 8mph.
2nd gear; between 2 and 3mph.
1st gear; never.

It's tricky to bump start in 2nd gear without causing a knock or lurch so I advise against it. Use your starter if you are going this slow.

If there is any kind of lurch or knock sound when you bump start you are doing it at too high a speed for the gear you are trying to do it in and/or letting the clutch out to quickly!

To bump start: make sure your ignition is in the ON position. Put in the desired gear and let the clutch out as if you were doing a normal shift. If you do it too slow it will not work and if you do it too fast it will cause a knock or lurch which I don't think is good for the engine or tranny. As soon as the ignition catches, IMMEDIATELY put the clutch back in and engage the appropriate gear for your driving speed. Immediately putting the clutch back in will help prevent any damage being done to your engine or tranny.

Disclaimer:
I have no knowledge of the ill effects on the engine or related components from bump starting properly on a cold engine. I've been doing it for a year (even in winter) and while I had some undesirable effects for a short while (I was having faulty alternator issues), in the last several months the car has been purring like a kitten.

City driving.
1. Saving fuel in the city environment is all about LOOKING AHEAD and paying vigilant attention to what the traffic lights ahead of you are doing and more importantly what traffic ahead of you is doing. The better you can predict what's going to happen in front of you the more fuel you have the potential to save. It's all about ROLLING up to the traffic lights! Let the other cars accelerate by you only to have to slam on the breaks for the red light. Half the time you'll roll through the green light that you gave enough time for the red light to become, while the other cars have to get going from a stop. Avoid non thinking REACTIONARY driving. Employ the PROACTIVE model of responding ahead of time to what people in front of you are doing. Keep as much distance between you and the cars in front of you without keeping enough distance for someone to pull out in front of you.

2. Accelerate slowly and shift at 1500rpm from 1st and 2nd gears. When you are going fast enough to keep up with traffic coast in neutral for a bit (or with the engine off if your engine isn't warm yet) until you need to accelerate again to keep up with traffic.

3. Remove any extra weight from your car that you don't absolutely need to haul around with you. The VX is a very light car. Any extra weight has more negative effect on gas mileage than in other cars.

I encourage others to challenge, disagree or revise any of my points!
Thanks.

[theholycow]

I would revise the terminology used above. Each person's opinion of exactly how to describe things differs, but above it seems that "Pulse & Glide" is applied, without further qualification, to both engine-on P&G and engine-off P&G. I prefer to describe engine-on P&G as merely P&G, and engine-off P&G as EOC P&G or just EOC (Engine-Off Coasting).

Also, I don't recommend EOC for new hypermilers unless they are already comfortable with P&G first.

One technical point I'd question is being light on the throttle during acceleration. Unless you're trying to use lean burn (can you, during acceleration?), wouldn't you want to reduce pumping losses by laying on the gas pretty hard (and shifting even lower if you're accelerating too fast)? That strategy is very effective in my car, but I don't know if it would be in a VX.

[jmf]

I would recomend a lean burn monitor. You can accelerate quite well in lean burn if you can see where the limit is. Alot of the time I only have to back off the thottle a little to stay in LB, and still accelerate. I haven't had any luck with P&G or EOC, I try to just stay steady, slow a little on the hills and brake as little as possible.
justin

[1993CivicVX]

Originally Posted by theholycow

I would revise the terminology used above. Each person's opinion of exactly how to describe things differs, but above it seems that "Pulse & Glide" is applied, without further qualification, to both engine-on P&G and engine-off P&G. I prefer to describe engine-on P&G as merely P&G, and engine-off P&G as EOC P&G or just EOC (Engine-Off Coasting).

Also, I don't recommend EOC for new hypermilers unless they are already comfortable with P&G first.

One technical point I'd question is being light on the throttle during acceleration. Unless you're trying to use lean burn (can you, during acceleration?), wouldn't you want to reduce pumping losses by laying on the gas pretty hard (and shifting even lower if you're accelerating too fast)? That strategy is very effective in my car, but I don't know if it would be in a VX.

Thanks for your reply holycow. I abstained from the acronym terminology cause I didn't want to scare off the new poster given the whole business of EOC itself can be pretty intimidating.

Yes, you can lean burn while accelerating. I used to accelerate harder but found that I wasn't getting as good gas mileage as feather footing acceleration, even though getting up to speed takes longer. I don't have an mpg scanner, but in my experience combining slow accelerations with excessive EOC is how I achieved 67mpg over three tanks (1600 miles or so).

[1993CivicVX]

Originally Posted by jmf

I would recomend a lean burn monitor. You can accelerate quite well in lean burn if you can see where the limit is. Alot of the time I only have to back off the thottle a little to stay in LB, and still accelerate. I haven't had any luck with P&G or EOC, I try to just stay steady, slow a little on the hills and brake as little as possible.
justin

This is really the best way to go. You don't need a lean burn monitor, you just gotta "feel" it . Which is more fun imo. But it would be cool to have a monitor.

[mnstrvx]

thanks again for the info. i just stepped back into this section briefly and noticed more posts! lol...

I am currently attempting more P&G (not EOC). I don't feel "comfortable" with EOC since I have a heavy traffic commute both ways (to and from work), and I don't believe the wear and tear on the drivetrain is "worth" it. although i might try this in the future.

in AZ heat, the engine running cold isn't much of an issue.

I ahve been noticing better MPG lately. With more attention to driving habbits... I have been "busy" with the gas log, as I find it to be a nice little tool.

[mnstrvx]

BTW, the yukon has the "stock" tire size, but not the stock tires. The tires state "max" psi at 35!! and that is what the car is set at

[mnstrvx]

I am pleased with the ability to "compare" my current MPG log with the vehicles stated city mpg rating, actually I am doing slightly better. Keep in mind that AZ is already seeing temperatures in the 105-110 range so the AC has been on ALL the time since I purchased the VX... i would imagine that I would see an increase in MPG if i was not using the AC. (although definately not an option right now).

I cannot imagine that this car will do "better" on the highway? With say, 65-75mph speeds? Anyone care to share their highway driving MPG experiences? the mpg rating is suppose to be 55 highway.

[theholycow]

Originally Posted by mnstrvx

I am currently attempting more P&G (not EOC). I don't feel "comfortable" with EOC

There is nothing at all wrong with that. Nobody should do it if they don't feel comfortable with it.

Originally Posted by mnstrvx

Keep in mind that AZ is already seeing temperatures in the 105-110 range so the AC has been on ALL the time since I purchased the VX... i would imagine that I would see an increase in MPG if i was not using the AC. (although definately not an option right now).

There would be an increase, but there's more important things than fuel economy -- like not having heat-related health problems, and not feeling too uncomfortable. With the temperature that high you get a large benefit to fuel economy anyway, at worst it is canceled out by the AC.

I cannot imagine that this car will do "better" on the highway? With say, 65-75mph speeds?

Most cars do better on the highway. While they're subjected to higher speeds which increase aerodynamic drag and engine RPM, they don't have to stop and go. When you brake you discard energy that you've already made out of fuel and is a huge effect on FE. Plus, the VX has lean burn, which I'm sure works a lot better for steady cruising than it does for city traffic. I think many VX drivers go really slow on the highway though, so I don't know how well it does at 65-75mph.

Originally Posted by mnstrvx

BTW, the yukon has the "stock" tire size, but not the stock tires. The tires state "max" psi at 35!! and that is what the car is set at

If the maximum is truly 35psi (and if the Yukon recommends 35psi), that means they are probably near their maximum load rating too. I would not want want to run those tires on that vehicle.

However, it may be ok to use 44 or 51 psi as your maximum. I would not recommend it and I would not do it - not for worry about the tire or any practical effect, but for legal ramifications if there was a tire failure during (or causing) an accident. I suspect that exceeding the stamped maximum could put you in a position of liability that you wouldn't be in had the tire failed at a pressure not exceeding the sidewall stamp.

http://www.geocities.com/barrystiretech/loadtables.html
Edited for brevity, more detail at the link...

it is permissible to stamp the sidewall of the tire as having a maximum inflation of 35 psi, or 44 psi or 51 psi.

If you were to dig to find the US regulation that covers what is supposed to be stamped on the sidewall of the tire the regulation is unclear which of those values it is supposed to be.

Most everyone in the tire industry reads the regulation that either 44 psi or 51 psi is the proper value for SL tires. However, a few tire manufacturers - notably the Michelin group (Michelin, Uniroyal, and Goodrich) have interpreted this differently and read the regulation to mean that for S and T speed rated tires, 35 psi should be stamped on the sidewall, while H and higher are supposed to read 44 or 51 psi.

That means for otherwise comparable tires, you will find different maximum pressures stamped on the sidewall. This means you SHOULD NOT use the pressure stamped on the sidewall as any sort of reference point, except, of course, what it says - a maximum.
and there are a couple exceptions to that!!

[turbothrush]

I cannot imagine that this car will do "better" on the highway? With say, 65-75mph speeds? Anyone care to share their highway driving MPG experiences? the mpg rating is suppose to be 55 highway.[/QUOTE]

At a true 60 mph ( GPS speed ) with a flat road and zero wind my vx does 56 mpg measured with my Mpguino. I would think 65-75 mph would be a good bit less. I also would like to here what others get at highway speeds.