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#1525026 - 07/08/09 10:16 AM Re: coasting in nuetral in toyota [Re: IndyIan]
brianl703 Offline


Registered: 05/07/04
Posts: 10487
Loc: Manassas, VA
The problem with the Scangauge2 is that it doesn't use fuel injector pulsewidth information because that is not a standard OBDII PID. (It's manufacturer specific). I believe it calculates fuel economy based on MAF and/or MAP readings, and the fact that you must set the engine size for best accuracy with the Scangauge2 is more evidence in that direction.

Most all fuel injected vehicles do cut fuel during deceleration. It reduces emissions and increases fuel economy. There are some situations where there may be fuel injected during long periods of deceleration to keep the cats warm, but for the most part the fuel is cut off.

When my Saab 93 is decelerating in gear, it's pretty noticeable when the fuel is turned back on at around 1000RPM. I don't know if that's a bug or a feature...the Fords I've had, it wasn't noticeable at all, but maybe Saab's thinking is that the driver ought to know when it's time to push the clutch in before the engine stalls.

On the pre-OBDII EEC-IV Fords ('91 Escort, '95 Contour) I looked at with a DLC-compatible scantool (the AutoXray) that showed fuel injector pulsewidth, the pulsewidth went to 0mS during deceleration.

I wasn't happy to find out that OBD-II scantools usually cannot get fuel injector pulsewidth information because it is manufacturer-specific. I have one that can get pulsewidth information from Fords, but not from Saabs. Oh well.

So...to summarize...the Scangauge II can't tell when the fuel injectors are turned off (pulsewidth 0). At least on most vehicles. It might be capable of getting it on some, but I've never seen any evidence to indicate that is the case.



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#1525294 - 07/08/09 01:48 PM Re: coasting in nuetral in toyota [Re: brianl703]
IndyIan Offline


Registered: 09/23/08
Posts: 5640
Loc: Ontario, Canada
I was aware that the SG2 can't monitor the fuel injectors directly but it seems to know when my tracker has cut fuel and when it starts adding it again at 1300 rpm. It registers fuel usage again at the same time the engine starts to pull again.
How? I don't really know but maybe it picks up something to do with the long term fuel trend? ie data is being collected again?

I know for sure than in a manual car you'd always want to coast in neutral if you were pulse and gliding on a flat road.

Also I'd bet the auto on a 95 camry drops out of lockup with no throttle so the engine has to have gas to maintain idle speed atleast as I think the engine would stop as its below the stall rpm of the torque converter? I don't really understand all the intricies of automatics and I'd think there are several different ways they could be run so probably you can't generalize what's best for every car.
_________________________
07 Focus ZXW, 5spd manual, 92km M1 5W20
03 Tracker, 5spd manual, 262km, Valvoline Syn 5W30

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#1525356 - 07/08/09 02:21 PM Re: coasting in nuetral in toyota [Re: IndyIan]
brianl703 Offline


Registered: 05/07/04
Posts: 10487
Loc: Manassas, VA
It might sense the additional flow through the MAF or the decreased vacuum at the MAP as the idle air control valve is opened when the engine drops below 1300RPM. The Fords, as I recall, keep the idle air control valve closed during deceleration, and open it again as the engine speed drops closer to idle.

As far as the transmission on the 95 Camry, it depends. Most with an electronic torque converter lockup unlock it only if the brake is pressed or the accelerator pedal is pushed beyond a certain limit. They don't automatically unlock it because the throttle is closed. The tachometer would be a good way to see what's going on with the foot off the gas.

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#1525914 - 07/08/09 09:28 PM Re: coasting in nuetral in toyota [Re: y_p_w]
KLowD9x Offline


Registered: 07/26/05
Posts: 313
Loc: Lugoff, SC
 Originally Posted By: y_p_w
 Originally Posted By: daves66nova
 Originally Posted By: JHZR2
I assume this is an AT equipped car? 4-speed?
yes it is,4-spd auto. So all safe then?

Theoretically safe as long as you're going forward. However - coasting in neutral is generally a better idea in manual transmission cars.

I also thought that one potential problem could be an accidental shift into reverse (I know there's usually a lockout) when the intent is to shift into drive.

There's very little penalty to actually staying in drive for that kind of waiting. I sometimes coast briefly with a manual transmission, but I frankly wouldn't bother with an auto.


This is why you can shift from drive to neutral and back again without having to press the shifter button in.

You can also slide from reverse to neutral to drive without pressing in the button. However, you can not go back to reverse once you have slid the shifter into neutral.

And, on the flip side, L to 2 to 3 to drive (depending on how many gears you have) doesn't require pushing in the button.

(I am REALLY tired and can't remember the name of the button, I think it's a detent, but meh, you know what I am talking about.)

So, you CAN shift between neutral and drive without worrying about hitting reverse.


Edited by KLowD9x (07/08/09 09:29 PM)
_________________________
1993 Volvo 850 2.4i (280K miles, Valvoline Maxlife Full-syn 5w30)
2004 Volvo S60 2.4i (130K miles, Mobil1 0w40)

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#1525933 - 07/08/09 09:40 PM Re: coasting in nuetral in toyota [Re: KLowD9x]
BuickGN Offline


Registered: 10/18/07
Posts: 3756
Loc: CA
 Originally Posted By: KLowD9x
 Originally Posted By: y_p_w
 Originally Posted By: daves66nova
 Originally Posted By: JHZR2
I assume this is an AT equipped car? 4-speed?
yes it is,4-spd auto. So all safe then?

Theoretically safe as long as you're going forward. However - coasting in neutral is generally a better idea in manual transmission cars.

I also thought that one potential problem could be an accidental shift into reverse (I know there's usually a lockout) when the intent is to shift into drive.

There's very little penalty to actually staying in drive for that kind of waiting. I sometimes coast briefly with a manual transmission, but I frankly wouldn't bother with an auto.


This is why you can shift from drive to neutral and back again without having to press the shifter button in.

You can also slide from reverse to neutral to drive without pressing in the button. However, you can not go back to reverse once you have slid the shifter into neutral.

And, on the flip side, L to 2 to 3 to drive (depending on how many gears you have) doesn't require pushing in the button.

(I am REALLY tired and can't remember the name of the button, I think it's a detent, but meh, you know what I am talking about.)

So, you CAN shift between neutral and drive without worrying about hitting reverse.


Every car is different. On my TL I can definately shift into reverse by accident. It has no button, just a brake interlock.
_________________________
84 Buick GN. 10.60@127 old times. 602hp 620lbs.
06 Acura TL. Lots of suspension and brake mods.

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#1526281 - 07/09/09 08:52 AM Re: coasting in nuetral in toyota [Re: BuickGN]
Char Baby Online   content


Registered: 05/25/05
Posts: 7303
Loc: Rochester NY
I was told differetly by my brother-in-law, who is on of the best car guys that I know. He says: Coasting in nuetral(automatic tranny) is not the best thing to do because the torque conveter and the wheels need to be turning at the same speed. When shifting into "N", the torque converter slows down to engine speed(RPM) while the wheels via the shafts are spinning at a much higher speed.
He and I both agree though that we have never heard of any problem from doing this but, who knows!
_________________________
"Finally Retired"!

1980 Firebird FORMULA V8-NEW
2001 Lexus RX-300 V6-NEW
2004 Nissan Altima 2.5S-NEW
2006 Mazda 3i 2.0L-PreOwned

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#1526928 - 07/09/09 07:17 PM Re: coasting in nuetral in toyota [Re: Char Baby]
olddognewtrks Offline


Registered: 08/20/03
Posts: 388
Loc: The Mid South
My best guess regarding illegality: Decades ago, when these laws were enacted, cars and trucks had really lousy brakes, and often non-synchronized gearboxes. If your brakes overheated on a downhill run, and you couldn't get it into gear for engine braking, you were toast. Solution? Mandate engine braking/running in gear. (Anyone here remember Harry Chapin's song "30,000 pounds of Bananas"?)
_________________________
Old enough to know better, gettin' past too young to care. Darn it!

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#1527331 - 07/10/09 12:57 AM Re: coasting in nuetral in toyota [Re: Char Baby]
BuickGN Offline


Registered: 10/18/07
Posts: 3756
Loc: CA
 Originally Posted By: Char Baby
I was told differetly by my brother-in-law, who is on of the best car guys that I know. He says: Coasting in nuetral(automatic tranny) is not the best thing to do because the torque conveter and the wheels need to be turning at the same speed. When shifting into "N", the torque converter slows down to engine speed(RPM) while the wheels via the shafts are spinning at a much higher speed.
He and I both agree though that we have never heard of any problem from doing this but, who knows!


What happens is if you leave it in gear and coast, the wheels drive the engine at a speed above idle and the computer shuts the injectors off. The engine consumes 0 fuel.

Take it out of gear and it consumes the same amount as it would idling, sometimes more since some cars elevate engine speed in neutral while it's moving.
_________________________
84 Buick GN. 10.60@127 old times. 602hp 620lbs.
06 Acura TL. Lots of suspension and brake mods.

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#1527336 - 07/10/09 01:01 AM Re: coasting in nuetral in toyota [Re: olddognewtrks]
BuickGN Offline


Registered: 10/18/07
Posts: 3756
Loc: CA
 Originally Posted By: olddognewtrks
My best guess regarding illegality: Decades ago, when these laws were enacted, cars and trucks had really lousy brakes, and often non-synchronized gearboxes. If your brakes overheated on a downhill run, and you couldn't get it into gear for engine braking, you were toast. Solution? Mandate engine braking/running in gear. (Anyone here remember Harry Chapin's song "30,000 pounds of Bananas"?)


My highway patrol friend says it has to do with "control". At a redlight you're supposed to be able to pop the clutch/let off the brake and hit the gas and move out of the way if the need should arise. Same if you're going down the freeway and you need to accelerate quickly for an emergency.
_________________________
84 Buick GN. 10.60@127 old times. 602hp 620lbs.
06 Acura TL. Lots of suspension and brake mods.

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#1527423 - 07/10/09 05:29 AM Re: coasting in nuetral in toyota [Re: BuickGN]
demarpaint Offline


Registered: 07/03/05
Posts: 21316
Loc: NY
 Originally Posted By: BuickGN
 Originally Posted By: olddognewtrks
My best guess regarding illegality: Decades ago, when these laws were enacted, cars and trucks had really lousy brakes, and often non-synchronized gearboxes. If your brakes overheated on a downhill run, and you couldn't get it into gear for engine braking, you were toast. Solution? Mandate engine braking/running in gear. (Anyone here remember Harry Chapin's song "30,000 pounds of Bananas"?)


My highway patrol friend says it has to do with "control". At a redlight you're supposed to be able to pop the clutch/let off the brake and hit the gas and move out of the way if the need should arise. Same if you're going down the freeway and you need to accelerate quickly for an emergency.


Does that mean legally you should be stopped at a light with the clutch depressed and the car in gear? That would really wear out a Throw Out Bearing early.
_________________________
GOD Bless our Troops


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#1527901 - 07/10/09 02:48 PM Re: coasting in nuetral in toyota [Re: demarpaint]
BuickGN Offline


Registered: 10/18/07
Posts: 3756
Loc: CA
 Originally Posted By: demarpaint
 Originally Posted By: BuickGN
 Originally Posted By: olddognewtrks
My best guess regarding illegality: Decades ago, when these laws were enacted, cars and trucks had really lousy brakes, and often non-synchronized gearboxes. If your brakes overheated on a downhill run, and you couldn't get it into gear for engine braking, you were toast. Solution? Mandate engine braking/running in gear. (Anyone here remember Harry Chapin's song "30,000 pounds of Bananas"?)


My highway patrol friend says it has to do with "control". At a redlight you're supposed to be able to pop the clutch/let off the brake and hit the gas and move out of the way if the need should arise. Same if you're going down the freeway and you need to accelerate quickly for an emergency.


Does that mean legally you should be stopped at a light with the clutch depressed and the car in gear? That would really wear out a Throw Out Bearing early.


I'm almost positive he said exactly that, in gear, clutch in. I'll clarify today.
_________________________
84 Buick GN. 10.60@127 old times. 602hp 620lbs.
06 Acura TL. Lots of suspension and brake mods.

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#1527908 - 07/10/09 02:54 PM Re: coasting in nuetral in toyota [Re: BuickGN]
gizzsdad Offline


Registered: 03/30/05
Posts: 460
Loc: Iowa
 Originally Posted By: BuickGN


I'm almost positive he said exactly that, in gear, clutch in. I'll clarify today.


Then I've been a scofflaw for a looong time!

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#1527934 - 07/10/09 03:25 PM Re: coasting in nuetral in toyota [Re: BuickGN]
y_p_w Offline


Registered: 05/06/05
Posts: 2527
Loc: SF Bay Area
 Originally Posted By: BuickGN
 Originally Posted By: demarpaint
 Originally Posted By: BuickGN
 Originally Posted By: olddognewtrks
My best guess regarding illegality: Decades ago, when these laws were enacted, cars and trucks had really lousy brakes, and often non-synchronized gearboxes. If your brakes overheated on a downhill run, and you couldn't get it into gear for engine braking, you were toast. Solution? Mandate engine braking/running in gear. (Anyone here remember Harry Chapin's song "30,000 pounds of Bananas"?)


My highway patrol friend says it has to do with "control". At a redlight you're supposed to be able to pop the clutch/let off the brake and hit the gas and move out of the way if the need should arise. Same if you're going down the freeway and you need to accelerate quickly for an emergency.


Does that mean legally you should be stopped at a light with the clutch depressed and the car in gear? That would really wear out a Throw Out Bearing early.


I'm almost positive he said exactly that, in gear, clutch in. I'll clarify today.

There's nothing in the California Drivers Handbook that specifically addresses that.

http://www.dmv.ca.gov/pubs/hdbk/driver_handbook_toc.htm

I did look up the California Vehicle Code (and "highway" is defined as any road or street):

 Quote:
21710. The driver of a motor vehicle when traveling on down grade
upon any highway shall not coast with the gears of such vehicle in
neutral.

I looked up anything in the Vehicle code that included "gear" or neutral", and couldn't find anything that addresses leaving a vehicle stopped in neutral at a light or stop sign. That obviously wouldn't be "coasting".

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#1527939 - 07/10/09 03:29 PM Re: coasting in nuetral in toyota [Re: BuickGN]
KLowD9x Offline


Registered: 07/26/05
Posts: 313
Loc: Lugoff, SC
 Originally Posted By: BuickGN
 Originally Posted By: KLowD9x
 Originally Posted By: y_p_w
 Originally Posted By: daves66nova
 Originally Posted By: JHZR2
I assume this is an AT equipped car? 4-speed?
yes it is,4-spd auto. So all safe then?

Theoretically safe as long as you're going forward. However - coasting in neutral is generally a better idea in manual transmission cars.

I also thought that one potential problem could be an accidental shift into reverse (I know there's usually a lockout) when the intent is to shift into drive.

There's very little penalty to actually staying in drive for that kind of waiting. I sometimes coast briefly with a manual transmission, but I frankly wouldn't bother with an auto.


This is why you can shift from drive to neutral and back again without having to press the shifter button in.

You can also slide from reverse to neutral to drive without pressing in the button. However, you can not go back to reverse once you have slid the shifter into neutral.

And, on the flip side, L to 2 to 3 to drive (depending on how many gears you have) doesn't require pushing in the button.

(I am REALLY tired and can't remember the name of the button, I think it's a detent, but meh, you know what I am talking about.)

So, you CAN shift between neutral and drive without worrying about hitting reverse.


Every car is different. On my TL I can definately shift into reverse by accident. It has no button, just a brake interlock.


I thought the 06 TL had a gated shifter? Even though it has no button, you have to move the shifter over to the side to shift it into reverse. There is still a stop to prevent you from popping it into reverse.

However, not like it matters, electro-hydraulic transaxles found in new vehicles will not engage reverse at speeds over a couple MPH. The TCM just won't allow it.
_________________________
1993 Volvo 850 2.4i (280K miles, Valvoline Maxlife Full-syn 5w30)
2004 Volvo S60 2.4i (130K miles, Mobil1 0w40)

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#1527947 - 07/10/09 03:37 PM Re: coasting in nuetral in toyota [Re: KLowD9x]
demarpaint Offline


Registered: 07/03/05
Posts: 21316
Loc: NY
I always sit at a light with my M/T van, in neutral, foot off the clutch. When the light turns green clutch gets pushed down, I shift into first and take off. The TOB would be toast waiting for some of these lights we Long Islanders or NYC dwellers have to deal with. I sometimes coast to lights (depends on a lot of things), so deciding which gear to use should it turn green is easier. Or if I have to stop I'm out of gear in neutral.
_________________________
GOD Bless our Troops


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