Coasting up to Lights.

[Ross]

Quote:
I have Ultraguage too, I'll check it tomorrow.

I saw more than 100 MPG with gear in neutral and 50-60 MPG in 6th while coasting down to red light or down hill.

My ultraguage shows the same thing. Much better on mpg coasting out of gear rather than in gear.

I will check on the open and closed loop thing in the morning

 

[George7941]

I checked the open/closed loop status on my truck today. Once it goes into closed loop (@ around 63C ECT) it stays in closed loop and NEVER goes into open loop, ever. This is in both hwy and city driving.

Here is what the FSM for my truck has to say about fuel cut-off

As you can see, fuel cut-off only happens on this truck under extended deceleration. As I mentioned in a previous post, I seldom see 0l/100km displayed on my SG in everyday driving.

Which brings up another question -- if the SG is using MAP/MAF to estimate fuel flow, why would it ever display 0l/100km?

 

[rationull]

Originally Posted By: George7941

Which brings up another question -- if the SG is using MAP/MAF to estimate fuel flow, why would it ever display 0l/100km?


My understanding was that it uses other values (TPS, I think) to detect fuel cutoff, and effectively "special cases" the consumption to 0.

I used to have an MPG gauge displayed on my SG2 and IIRC it would display "9999" when in fuel cutoff mode. I've had the SG for a long time, and in firmware revisions before they added the fuel cutoff detection it would simply read some very high MPG value, but not "infinite". I figured the value it used to display was based on the MAP/MAF readings.

I'm a little foggy on this though since I haven't used the SG2 for these purposes for a few years now.

 

[mechtech2]

Engine management systems do cut fuel when off the throttle in gear. This is generally a good thing.
But it varies when and which gear.
They keep them rather high, RPM wise.

Engine braking is a huge factor, and negates and works against the supposed savings[in gear] as opposed to coasting in neutral.

 

[George7941]

Originally Posted By: rationull
Originally Posted By: George7941

Which brings up another question -- if the SG is using MAP/MAF to estimate fuel flow, why would it ever display 0l/100km?


My understanding was that it uses other values (TPS, I think) to detect fuel cutoff, and effectively "special cases" the consumption to 0.

I used to have an MPG gauge displayed on my SG2 and IIRC it would display "9999" when in fuel cutoff mode. I've had the SG for a long time, and in firmware revisions before they added the fuel cutoff detection it would simply read some very high MPG value, but not "infinite". I figured the value it used to display was based on the MAP/MAF readings.

I'm a little foggy on this though since I haven't used the SG2 for these purposes for a few years now.


My ScanGauge was bought only a few months ago, so I think it is the latest version.

My SG displays 9999 LHK when I am idling at traffic lights and that is as it shoud be.

And, thanks, Mechtech, you have confirmed my observations on the behaviour of the truck.

 

[daves87rs]

I admit to be being a coaster..and I think it is why my tranies are still in good shape and my Balt brake pads are close to 50k in mostly city driving....


Never understood the racing from light to light...

 

[Ross]

I double checked my ultraguage. Mine does go into open loop when coasting up to stop lights in gear, but stays in closed loop when when coasting out of gear. My instant MPG is much higher out of gear than in gear coasting

 

[bigmike]

Originally Posted By: CATERHAM
It's best to leave it in gear and use the engine compression to naturally slow the vehicle using the brakes to finally stop and sliding the MT into neutral at the last moment.
But what I try to do is time the lights so that I don't have to stop at all at intersections. It's neat when you have some dufus pass you as you've started to ease off approaching an intersection only to sail past them already stopped as the light turns green.


It's not only neat, it's glorious and vindicating!

 

[Rand]

I thought most automatics just unlocked the torque converter when coasting. Is there a link somewhere that supports the transmission going into neutral when coasting?


edit: not sure why it says re:bigmike I was replying to a different poster

 

[Colt45ws]

I dont think any go into neutral while coasting. Just unlock the TC. Which is really stupid by the way. If you let off the gas for a second and get back into it you can feel the slight flare before it locks up again. Im going to have that behavior programmed out when I get it tuned.
Though, some transmissions do neutral out at a stop in Drive. My Mom's Fusion does this.

 

[Artem]

Originally Posted By: Ross
I double checked my ultraguage. Mine does go into open loop when coasting up to stop lights in gear, but stays in closed loop when when coasting out of gear. My instant MPG is much higher out of gear than in gear coasting


Something ain't right with the gauge setup or your engine.

All the cars that I've hooked up my Scan Gauge II showed WAY better MPGs while coasting in gear vs neutral with automatics.

With a manual transmission, the gauge shows 9999 MPG which basically means, the injectors are off and the transmission is spinning the engine.

Throwing it is neutral shows 70-150mpg depending on the speed I'm coasting in.

It's clearly more efficient to leave it in gear while coasting to a stop.

 

[Artem]

Originally Posted By: George7941
My ScanGauge was bought only a few months ago, so I think it is the latest version.

My SG displays 9999 LHK when I am idling at traffic lights and that is as it shoud be.

And, thanks, Mechtech, you have confirmed my observations on the behaviour of the truck.

Your gauge is setup wrong. It should be displaying 0mpg while idling at a stop. You are not moving and therefore getting absolutely ZERO miles to the gallon.

It's should only display 9999mpg when the injectors stop firing (coasting to a light in gear, for example)

 

[Artem]

Originally Posted By: mechtech2
Engine management systems do cut fuel when off the throttle in gear. This is generally a good thing.
But it varies when and which gear.
They keep them rather high, RPM wise.

Engine braking is a huge factor, and negates and works against the supposed savings[in gear] as opposed to coasting in neutral.

If you're coming to a stop anyway, what does it matter?

Engine breaking (coasting in gear) up to a STOP makes more sense then doing so in neutral and here's why... If you're coasting to an eventual stop, engine braking slows you down so in the end, you apply less brakes (saving pad life)

Also, my Scan Gauge II shows that I'm getting infinite MPG while coasting in gear.
In neutral, it shows 70-150mpg depending on the speed I'm going.

It's clearly more economical (and from more then one perspective) to coast in gear when coming to a complete STOP.

 

[rationull]

Originally Posted By: Artem
Originally Posted By: George7941

My ScanGauge was bought only a few months ago, so I think it is the latest version.

My SG displays 9999 LHK when I am idling at traffic lights and that is as it shoud be.

And, thanks, Mechtech, you have confirmed my observations on the behaviour of the truck.


Your gauge is setup wrong. It should be displaying 0mpg while idling at a stop. You are not moving and therefore getting absolutely ZERO miles to the gallon.

It's should only display 9999mpg when the injectors stop firing (coasting to a light in gear, for example)


9999 (infinite) LHK (liters per 100 km) effectively the same as 0 mpg., fuel cutoff while coasting should be 0 L/100km.

 

[Artem]

Originally Posted By: rationull
Originally Posted By: Artem
Originally Posted By: George7941

My ScanGauge was bought only a few months ago, so I think it is the latest version.

My SG displays 9999 LHK when I am idling at traffic lights and that is as it shoud be.

And, thanks, Mechtech, you have confirmed my observations on the behaviour of the truck.


Your gauge is setup wrong. It should be displaying 0mpg while idling at a stop. You are not moving and therefore getting absolutely ZERO miles to the gallon.

It's should only display 9999mpg when the injectors stop firing (coasting to a light in gear, for example)


9999 (infinite) LHK (liters per 100 km) effectively the same as 0 mpg., fuel cutoff while coasting should be 0 L/100km.

did you not read the manual? When it displays 9999 "MPG" that means infinite gas mileage, that means the injectors are not firing so you're not burning any fuel and can coast to the moon and back. It does NOT mean ZERO MPG.

What LHK has to do with this when we're in America and use Gallons as a standard measurement is beyond me.

 

[demarpaint]

Originally Posted By: Artem
Originally Posted By: mechtech2
Engine management systems do cut fuel when off the throttle in gear. This is generally a good thing.
But it varies when and which gear.
They keep them rather high, RPM wise.

Engine braking is a huge factor, and negates and works against the supposed savings[in gear] as opposed to coasting in neutral.

If you're coming to a stop anyway, what does it matter?

Engine breaking (coasting in gear) up to a STOP makes more sense then doing so in neutral and here's why... If you're coasting to an eventual stop, engine braking slows you down so in the end, you apply less brakes (saving pad life)

Also, my Scan Gauge II shows that I'm getting infinite MPG while coasting in gear.
In neutral, it shows 70-150mpg depending on the speed I'm going.

It's clearly more economical (and from more then one perspective) to coast in gear when coming to a complete STOP.


Good info, its also safer to coast in gear.

I hope that comment doesn't start WW-III. JMO

 

[rationull]

Originally Posted By: Artem
Originally Posted By: rationull
Originally Posted By: Artem
Originally Posted By: George7941

My ScanGauge was bought only a few months ago, so I think it is the latest version.

My SG displays 9999 LHK when I am idling at traffic lights and that is as it shoud be.

And, thanks, Mechtech, you have confirmed my observations on the behaviour of the truck.


Your gauge is setup wrong. It should be displaying 0mpg while idling at a stop. You are not moving and therefore getting absolutely ZERO miles to the gallon.

It's should only display 9999mpg when the injectors stop firing (coasting to a light in gear, for example)


9999 (infinite) LHK (liters per 100 km) effectively the same as 0 mpg., fuel cutoff while coasting should be 0 L/100km.

did you not read the manual? When it displays 9999 "MPG" that means infinite gas mileage, that means the injectors are not firing so you're not burning any fuel and can coast to the moon and back. It does NOT mean ZERO MPG.

What LHK has to do with this when we're in America and use Gallons as a standard measurement is beyond me.




I do not need to read the manual to understand units, thanks. Read the quoted posts. George7941's post said that he reads 9999 LHK while stopped at a traffic light. That's "infinite" liters of fuel per 100 km, same as 0 miles/gallon. You will notice that George is in Canada, which is how liters and kilometers come into this.

You responded saying that his gauge setup was wrong, that "it should be displaying 0mpg while idling at a stop." I was simply pointing out that his post was not talking about the MPG gauge, but the LHK (liters/100km) gauge. It would display 0 MPG if looking at the MPG gauge, or 9999 LHK if looking at the LHK gauge. It's behaving correctly based on his description in the post I was quoting.

 

[cchase]

Originally Posted By: Artem

It's clearly more economical (and from more then one perspective) to coast in gear when coming to a complete STOP.


Only if you can maintain a speed in gear. Getting infinite mpg while coasting to a stop is not better than coasting in neutral and maintaining speed.

 

[Artem]

if you are coasting to a definite STOP up ahead, there is no need to coast in neutral while trying to maintain speed (you're going to hit the brakes soon to STOP!) so your statement doesn't make sense to me AT ALL!

Now if you're talking about coasting a bit and then getting back on the gas, coasting 100-200 feet in gear, getting infinite MPGs (as per the Scan Gauge) and then simply reapplying gas (if the light turns green and you can go) is better then;

*Hit the clutch
*take it out of gear
*coast 100-200 feet burning x amount of fuel while the engine is maintaining idle
*reapply the clutch
*put it back into the proper gear
*rev match / ease the clutch to re-engage (however you do it)
*get back on the gas

^seems like more wear and tear on drivetrain components all while burning more fuel.

 

[Artem]

Originally Posted By: rationull
I do not need to read the manual to understand units, thanks. Read the quoted posts. George7941's post said that he reads 9999 LHK while stopped at a traffic light. That's "infinite" liters of fuel per 100 km, same as 0 miles/gallon. You will notice that George is in Canada, which is how liters and kilometers come into this.

You responded saying that his gauge setup was wrong, that "it should be displaying 0mpg while idling at a stop." I was simply pointing out that his post was not talking about the MPG gauge, but the LHK (liters/100km) gauge. It would display 0 MPG if looking at the MPG gauge, or 9999 LHK if looking at the LHK gauge. It's behaving correctly based on his description in the post I was quoting.

Ok, i got it now. Thanks