i have idled cars for a long lond time and never once had a ac compressor blow up

9/6/2005 9:14:43 AM

I don't see how that would happen either. Maybe if the compressor was running the whole time, but since it cycles and there's an over pressure switch, I don't see it being a problem nowdays.

I'm also surprised that they haven't said anything about the routes I take from pool to pool. I've also turned off the truck in the middle of the road sitting in construction traffic a couple times hoping they would ask me what that was about but they never did. They questioned matt several times about the places he stopped. He was planning on turning off the truck at every stop sign and stoplight just to piss them off, but he never did.

9/6/2005 9:39:24 AM

I don't do this but I wonder about cutting off the engine at long lights.
This is what the hybrids do automatically (at stops).
I read that, for example, drivers in Scandinavia do this as a rule, which is why
the ignition key in Saab's are located next to the gear shift.

I worry about chewing through starters and shit like that.

9/7/2005 8:25:17 AM

Quote :

"i thought that i read on here that having all of your windows down wastes more gas than have your AC on"

Yep...Somewhere around 45MPH and above on most cars you will get better gas mileage by running the AC as opposed to having the windows down and taking the increased air resistance.

9/7/2005 9:54:05 AM

[stupid question]
Shifting into neutral at stoplights doesn't gain you anything in a car with an automatic, right?
[/stupid question]

Quote :

" the tips mentioned here will help a little bit, but you could double your mpg by switching cars"

Unless you happen to be in the market for other reasons, that's a bit drastic. Also, if you currently have a vehicle that doesn't get very good mileage, you're not going to be able to easily sell it or get much on trade-in currently. I think my Lincoln would be worth about $5 if I tried to sell it right now.

9/7/2005 10:26:13 AM

NO FAT BITCHES!

9/7/2005 11:32:54 AM

bring your lunch to work

9/7/2005 12:09:11 PM

don't pay for your whores

9/7/2005 10:29:24 PM

if they checked where i stopped they would have seen my house, my girlfriends, my parents, stores, banks, etc...

i dont know how i got away with that shit

9/7/2005 10:34:35 PM

i coudla swore they did that on a episode of mythbusters and the car w. the windows down went drove a bit further.

9/7/2005 11:00:47 PM

^ i saw that one too

9/7/2005 11:06:38 PM

Put your tailgate up.

9/10/2005 2:00:32 AM

take the bus.

I haven't filled up my 4runner since when gas was 2.50 a gallon.

9/10/2005 11:39:00 AM

If you drive a pickup, keep your tailgate down, especially for highway driving. You get at least a mile more per gallon.

9/10/2005 11:40:37 AM

No, you WONT. Believe it or not, your truck has less air-resistance with the tailgate up.

9/10/2005 12:01:27 PM

set your plug gap to the max you can without losing spark

9/10/2005 1:29:51 PM

^^bullshit. i found it hard to believe when i was told about the improvement until i tried it myself. i gained about 50 more miles to the tank when i leave the tailgate down which is a little over 1 mpg gain. and no, i didn't change any driving habits during my test either.

9/10/2005 1:36:17 PM

^^^ The air hits the tailgate directly if it is up. When down, air can flow out with less resistance. That's not even simple physics, it's common sense.

9/10/2005 2:22:34 PM

YOU ARE DEAD WRONG ABOUT THE TAILGATE

take a fluids class and you'll realize the tailgate circulates the air in the bed, which means the air flowing from the roof rides on the air bubble and passes over the tailgate without hitting it.

it's not simple physics, it's fluid mechanics that matter

[Edited on September 10, 2005 at 2:35 PM. Reason : b]

9/10/2005 2:34:22 PM

^that has got to be the biggest bunch of bullshit i have ever heard. going by that theory, no air should enter the cab of the truck when the windows are down because the air would flow past due to the "air bubble" that has formed inside.

a calculator doesn't lie. i know for a fact i gained mileage with my fucking tailgate down.

so, you are wrong.

9/10/2005 2:41:35 PM

oh really?

you're just being STUPID now. CALL UP FORD, DODGE, OR CHEVY AND ASK THEM FOR THEIR WINDTUNNEL DATA.

truck manufacturers have studied this time and time again and you're just a dumbass for not believing it.

there are SO many factors in gas mileage like tires, air density, temperature, weather, driving habits, that it is impossible to accurately recreate the exact same conditions to do an evaluation like yours that has any scientific merit.

BTW: the dynamics of your cab windows being down and the bed of the truck ARE SO COMPLETELY DIFFERENT THAT YOU CANNOT COMPARE THEM LOGICALLY.

[Edited on September 10, 2005 at 2:49 PM. Reason : this argument is old as trucks]

9/10/2005 2:48:17 PM

I would agree it is best left up, but the difference between the two is probably fairly small.

9/10/2005 2:52:35 PM

it is.

9/10/2005 2:56:03 PM

Probably better for the structure of the vehicle in a rear collision to have it up as well.

9/10/2005 2:57:55 PM

yeah, because the manufacturers have designed the trucks for driving with the tailgate up.

what use is a bumper if you can't use it?

9/10/2005 3:05:38 PM

Quote :

"Investigators at the National Research Council of Canada have determined that pickup truck aerodynamics is generally degraded — not improved — by the often-seen practice of lowering or removing the tailgate. Drag is generally greater and, to the detriment of yaw stability, rear lift can be increased by as much as 60 percent. Popular mesh tailgates worsen aerodynamics of these vehicles as well."

http://www.roadandtrack.com/article.asp?section_id=18&article_id=1455

Quote :

"^^bullshit. i found it hard to believe when i was told about the improvement until i tried it myself. i gained about 50 more miles to the tank when i leave the tailgate down which is a little over 1 mpg gain. and no, i didn't change any driving habits during my test either."

You saved enough gas out of ONE TANK to go FIFTY MILES because you tailgate was down? And you're crying bullshit on me?

9/10/2005 3:06:29 PM

i didn't beleive it either till kleinstruer said it and explained why

Quote :

"^that has got to be the biggest bunch of bullshit i have ever heard. going by that theory, no air should enter the cab of the truck when the windows are down because the air would flow past due to the "air bubble" that has formed inside."

no by that logic air would come forward in the back window
and oh wait... it does

[Edited on September 10, 2005 at 4:09 PM. Reason : .]

9/10/2005 3:57:34 PM

Quote :

"You saved enough gas out of ONE TANK to go FIFTY MILES because you tailgate was down? And you're crying bullshit on me?"

ok. don't believe me. but if you don't have one, get someone you know with a truck to try it himself.

9/10/2005 6:20:46 PM

Quote :

" coudla swore they did that on a episode of mythbusters and the car w. the windows down went drove a bit further. "

yeah but i think they were driving at 45 mph, and above that is when using AC is supposed to help

9/10/2005 7:00:09 PM

I have a truck and in high school, I took off my tailgate to see if it helped. It didn't.

9/11/2005 10:20:48 PM

i know when i took the tailgate off my truck i got an extra 175 miles on a tank

prove i didnt

9/11/2005 10:31:03 PM

what saves the most gas is going the speed limit. 65vs75 saves something like 17 percent

9/11/2005 10:39:27 PM

what about coasting to a light with the clutch engaged (engine idling) vs engine braking w/ no throttle?

9/11/2005 10:41:45 PM

Quote :

"65vs75 saves something like 17 percent"

wouldn't that depend a lot on the car?

9/11/2005 10:50:41 PM

^^ you're better off in gear than in neutral when approaching a signal or stop

9/12/2005 12:30:06 AM

let this FUCKING thread die already.

9/12/2005 12:32:12 AM

I agree w/ the bus thread.

I filled up 3 weekends (or maybe it was 2...) ago in Tarboro on the way back to Raleigh at $2.44 a gallon and am still about 1/4 of a tank.

BTW 16 gallon tank, ~25mpg.

[Edited on September 12, 2005 at 1:29 AM. Reason : .]

9/12/2005 1:29:14 AM

Couple of quick comments;

Having the clutch in for long periods of time is generally not a good practice, as it leads to significantly more wear for some driveline components, specifically (but not limited to) the throw out bearing.

Also, coasting to a light, or coming up on slower moving traffic in gear and off throttle will save much more fuel in most modern fuel injected vehicles as under these conditions fuel is usually completely cut. (I've heard however that some Hondas/etc are now adopting a reduced fueling strategy under these conditions but not fully turning the injectors off to keep the catalytic converters' temperatures high for better emissions).
Ahmet

9/12/2005 5:01:16 AM

Quote :

"as under these conditions fuel is usually completely cut."

I kinda doubt that. Where did you read this/hear this/etc?

9/12/2005 6:57:28 AM

There are ofcourse, more... You can take a trip to your local performance shop with a dyno and wideband and observe this for yourself on most cars not running an aftermarket ECU or complete retuning of whatever factory engine management there is.
Ahmet

9/12/2005 11:14:47 AM

i've heard that those bosch books cover mostly jetronic and dont have as much info about the "modern" motronic system.

[Edited on September 12, 2005 at 11:28 AM. Reason : that 2nd book has a picture of a car that is at least 13 years old.]

9/12/2005 11:27:16 AM

Quote :

" I kinda doubt that. Where did you read this/hear this/etc? "

Agreed. I'm assuming he meant to say that the fuel consumption is cut significantly, not completely.

9/12/2005 11:29:55 AM

Quote :

"On the interstate run your ac and keep the windows up. "

Been proven that this isn't true. Even on the highway, the AC eats gas far more than the drag from having your windows down.

They did this shit on MythBusters, and I can back it up with the 10,000 miles I drove this summer. I saw 6-8mpg better with the windows down and no AC.

9/12/2005 12:00:59 PM

its still better (for gas mileage) to roll up in neutral than to just coast in gear.

9/12/2005 12:21:17 PM

Under the conditions I've described, the injector duty cycle is dialed back to 0. This means no fuel injected what so ever (save for a leaking injector perhaps). Look at your BMW's consumption gauge on in gear deceleration from higher rpms, you will see that it will go off the chart.

This is fairly frustrating for me. I posted some information, the credibility of which was questioned, so I posted reference. I don't know how else to share good technical information with the populace of this board.

There are various iterations of even the J, L, et al -tronic. "Motronic" most variations of which are considered "modern" or current, rely on the same principles. As I pointed out, there's a few variations to the basic concept coming out from some manufacturers today.
Ahmet

9/12/2005 1:40:07 PM

ok.. here's my "proof"

when i have my MFA (multi function array) set to "instantaneous MPG" and, for example, i'm going 45 or 50 mph. if i take my foot off the gas, in gear, iMPG goes to like 40-70. if i push in the clutch it goes "off the chart" to 199 (max it will register).

on top of that, coasting will help conserve more momentum than leaving it in gear and off throttle. i guess this isnt as important when the light is red, tho.

edit:
i havent done any datalogging with injector duty cycle, but if you really want, i will hook up the vag-com and give you some hard numbers.

edit #2:
it's motronic

[Edited on September 12, 2005 at 2:08 PM. Reason : -]

9/12/2005 2:03:33 PM

Ya, I would like that if it's not too much trouble. It appears I'm not as accurate nowadays as I could be...

Can you also get me your motronic version #?
Thanks
Ahmet

9/12/2005 2:11:34 PM

i sold my vag-com cable to a buddy, but i will be sure to run some tests for yah..

im not trying to say you're wrong.. its just not what i have noticed..

9/12/2005 2:16:49 PM

OK, keep in touch w/me if you can get a hold of the cable.

A few things I should note;
I know what I've posted to be true for most european cars through the mid 90s. Absolutely positive about quite a few from both factory documentation/design manuals, as well as 3rd party confirmation and personal experience.

However, injector cut off is only employed under *very low load conditions and from higher rpm. Injectors are opened again at some pre determined value, well above idle. Some manufacturers (especially those with full sequential injector management) may have switched to a "softer" cut, and others still (as noted earlier w/new Hondas etc.) look like they maybe going to simply reduced fuel, and not cut.

Lastly, your indicator may be switching between gallons or liters per hour and miles per gallon. Different computers use different parameters to decide when to do the shift. Most Porsches forexample are speed dependent. The 40-70 range would correspond well with a "per hour" consumption value quite well also.

Anyway, I'm interested but no rush. Feel free to be in touch when/if you get a chanse.
Ahmet

9/12/2005 2:26:29 PM

no.. it stays with MPG.

it is an '03 vw. and typically coming down from 3-4k or so..

injector pulse will be in milliseconds, rather than like 80% duty cycle.

i'll try to get up with someone to get some actual numbers

9/12/2005 2:33:20 PM