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There are times when you have to stop, such as picking up or dropping off a passenger, waiting at a train crossing, traffic light, etc. no matter how good a driver you are. It is these times that the stop-engine technology shines. And since it is seemless to the driver, and saves natural resources, how can one not like it ? Sure, waiting for a left hand turn at a traffic light the first time with this technology may be a little upsetting for the 1st 1/4 second, but you can easily anticipate this and get used to it.
RIT, I agree with you: it shines in those situations you listed. However, my concern is as Colt Hero states--the wear-and-tear on the starter and associated components, the additional load on the battery (not to mention in stop-and-go traffic, the battery may never get full recharged after all the additional starting cycles), and my greatest personal frustration (when it is not seamless) of coming to a stop with no cross traffic, coming to a red light and turning right, pulling into to garage, all those very "brief" stops when the engine stops for less than five seconds and then restarts; can't count the times I have pulled into my drive way, waiting for the garage door to finish open and the engine stops, or the times I have pulled directly into the garage and stopped--and the engine shuts off only to restart when I shift to Park--and then I turn the engine OFF. I have begun to drive with the trans in L and the range pushed to 9, thus defeating the start/stop feature completely in order to avoid the frustrations. Just my approach! :smile:
 

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I do understand the concern of wear and tear on the starter or battery, but there is a counter point. I don't know what GM is doing, but other manufactures use a little computer trickery to assist the stop/start. One of the main tricks is that the computer times the stop so that the engine is on the downward of a compression stroke. To start again, just injects a little gas in one cylinder and sparks it. That alone is enough to spin the engine over and keep the chain going.

The diesel owners are out of luck though. That has to use the starter. Seems absolutely dumb to force stop/start technology on something as fuel efficient as a diesel.

Again, I don't know if GM does this, just offering an overview of the tech.
 

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other manufactures use a little computer trickery to assist the stop/start. One of the main tricks is that the computer times the stop so that the engine is on the downward of a compression stroke. To start again, just injects a little gas in one cylinder and sparks it. That alone is enough to spin the engine over and keep the chain going.
Ohhhh ... that's a good idea. So the use of the starter is greatly reduced. Makes sense.

For those of you with this feature, can you actually *hear* the starter engaging? Just wondering.

Also - wonder why, instead of Start/Stop, they couldn't implement AFM-I (Active Fuel Management for Idling) whereby the engine drops down to 2 (or better yet, even 1) cylinders if stationary for more than X seconds. And then make this timer parameter changeable via the menus so it can be "tuned" by the driver, or even triggered on demand via a button on the steering wheel.
 

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I do understand the concern of wear and tear on the starter or battery, but there is a counter point. I don't know what GM is doing, but other manufactures use a little computer trickery to assist the stop/start. One of the main tricks is that the computer times the stop so that the engine is on the downward of a compression stroke. To start again, just injects a little gas in one cylinder and sparks it. That alone is enough to spin the engine over and keep the chain going.

Again, I don't know if GM does this, just offering an overview of the tech.
I like that approach, and if GM is doing that I would be much more comfortable letting the feature work.
 

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Ohhhh ... that's a good idea. So the use of the starter is greatly reduced. Makes sense.

For those of you with this feature, can you actually *hear* the starter engaging? Just wondering.
The next time I'm out and about, I'll use the start/stop feature and listen specifically for the starter to engage. I'll get back to the thread after.
 

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I do understand the concern of wear and tear on the starter or battery, but there is a counter point. I don't know what GM is doing, but other manufactures use a little computer trickery to assist the stop/start. One of the main tricks is that the computer times the stop so that the engine is on the downward of a compression stroke. To start again, just injects a little gas in one cylinder and sparks it. That alone is enough to spin the engine over and keep the chain going.



Again, I don't know if GM does this, just offering an overview of the tech.
Exactly. Mentioned this earlier in another other thread someone started regarding Start/Stop, but people skim or don't read entire threads, so go in circles. . . er not meaning you. But you would be surprised how many people just read last posts as though it has the complete synopsis or all that has been discussed.
:grin:

GM and other car makers also use another trick of storing transmission fluid in a ballast of some sort to assist restarts and takes off. Otherwise the transmission would suffer as well.
 

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The next time I'm out and about, I'll use the start/stop feature and listen specifically for the starter to engage. I'll get back to the thread after.
Whether the starter needs to be used or not depends on a few factors from what have gleaned. How long a stop, weather conditions, and who knows what else.

So, you may "hear" the starter engage some times, but not others.
 

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Ohhhh ... that's a good idea. So the use of the starter is greatly reduced. Makes sense.

For those of you with this feature, can you actually *hear* the starter engaging? Just wondering.

Also - wonder why, instead of Start/Stop, they couldn't implement AFM-I (Active Fuel Management for Idling) whereby the engine drops down to 2 (or better yet, even 1) cylinders if stationary for more than X seconds. And then make this timer parameter changeable via the menus so it can be "tuned" by the driver, or even triggered on demand via a button on the steering wheel.
I'll bet the stop/start is a lot cheaper to implement - a little bit of software code, and probably less damage to car.
 

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Also - wonder why, instead of Start/Stop, they couldn't implement AFM-I...
Meh... AFM is a pretty dirty word in the Silverado community. I use to think they were just being dramatic with their $200 devices to disable AFM. "I paid for a V8, and I'm getting a V8 consarnit!". Personally, I can't feel the switch from V8 to V4 and back, but I have learned that another reason guys disable it is because the lifters for the AFM cylinders are collapsing and causing all sort of problems. On top of that, the special oil manifold for the AFM system constricts. Also, other parts of the AFM system have led to lower oil pressure and some varnish/sludging.

All that, and AFM doesn't activate on idle. It's only when going down hill/coasting or on a reasonably flat grade. I'm guessing that at idle, the truck would shake like mad trying to stay running.
 

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Buggsy is on the money with the AFM issues that plague the owners of 2007 and on GM p/u owners, although they seem to have a partial handle on it with the 2014 and later models, hmm, 7 years to find a partial fix, sound familiar? I also frequent the GM p/u forums and am thankful that I have a pre-AFM low mileage 2005 model. But darn, I'm sacrificing 1 or 2 mpg for reliability and longevity.
 

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AFM is used on the new LGZ 3.6L V6 in Colorado/Canyon as well. Of course, thereare only 2 cylinders that are idled. So far, I have not heard of any issues regarding it.

As in the Silverado, it only goes into AFM under low loads mostly around town at slower city driving speeds. It does kick in rarely on the interstate or highway in very flat sections or slight down grades.

I can notice it very slightly at times, but it is very smooth when going back to V6 mode. A green "V4" mode comes on the DIC when it goes into that mode then changes back to "V6".

I will say this, the Colorado with the LGZ 3.6L has been getting 21 to 22 MPG around town in about 60% city (25 to 35 MPH) and 40% semi rural 40 to 55 MPH driving with many stops. This is better than I anticipated and equals or slightly bests the 2015 Equinox LFX 3.6L we also have.

On straight highway trips traveling 65 to 72 MPH I have gotten +26 to +28 MPG over 300 miles at a time fill up to fill up and hand calculated. The wind, hills and traffic make the most difference at highway speeds as usual.
 

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JayTee--Thanks for the confirmation of the start/stop restart technology. I missed the other thread--or missed your comment in it. Appreciate the clarification. I will now feel better using the feature.
 

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Exactly. Mentioned this earlier in another other thread someone started regarding Start/Stop, but people skim or don't read entire threads, so go in circles. . . er not meaning you. But you would be surprised how many people just read last posts as though it has the complete synopsis or all that has been discussed.
:grin:

GM and other car makers also use another trick of storing transmission fluid in a ballast of some sort to assist restarts and takes off. Otherwise the transmission would suffer as well.
The nine speed tranny has a accumulator that stores fluid and pressure.
 

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The next time I'm out and about, I'll use the start/stop feature and listen specifically for the starter to engage. I'll get back to the thread after.
Drove the E'Nox this evening and confirmed that the starter does NOT engage when restarting with the start/stop feature. I am truly glad to experience that and resolve my personal "major" concern with that feature. I will now comfortably let the feature perform without circumventing/defeating as I have previously. My thanks to JayTee, FLee, Colt Hero and any others who have assisted my in reaching this understanding! :smile:
 

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Stop/Start System Description and Operation
The Stop/Start System is used to improve fuel efficiency in stop/start driving. The vehicle automatically shuts down the engine in appropriate conditions at a traffic light, for example, resulting in zero tail pipe emissions and saving fuel which otherwise is used idling the engine when stationary. The engine instantly restarts when the driver is ready to move away.
As soon as the driver prepares to move away (by releasing the brake pedal and/or depressing the accelerator pedal), the engine will start; it only takes the system around 0.3 s to start the engine.
To support the increased number of engine starts, the starter motor is upgraded with a high performance electric motor and a stronger pinion engagement mechanism with reduced noise levels.
Along with the upgraded starter motor, advanced battery technology is required to ensure the vehicles battery can handle the frequent charge and discharge cycles common with stop/start operation. There is an intelligent battery sensor connected to the battery which continually monitors the battery charge and healthy state. The engine control module (ECM) uses this information from the intelligent battery sensor to determine if the battery charge and health is sufficient for an Stop/Start condition.
The Stop/Start system can reduce fuel consumption and carbon dioxide (CO2) emissions by up to 5% in mixed driving conditions. In an urban environment and in heavy traffic with frequent stops the savings may increase to as much as 10%.
There are also sophisticated controls in place to help ensure the Stop/Start System does not compromise the needs of either the driver or vehicle. For the engine to shutdown, the vehicle must be below 5 km/h (3 MPH), the selector lever in position D, and brake pedal depressed. To restart, the driver simply releases the brake pedal and the enhanced starter motor engages the engine. When the engine has been shut down by the Stop/Start System, a control indicator will be illuminated in the Driver Information Center (DIC). When the engine is restarted, the control indicator in the DIC extinguishes.
To ensure neither the needs of the driver or vehicle are compromised the engine will not shut down in the following circumstances:
  • Ambient and coolant temperature correlation does not match specified values.
  • Ambient temperature is less than −10°C (14°F)
  • Battery temperature is less than 0°C (32°F) or greater than 55°C (131°F)
  • Driver seat belt is not fastened and the drivers door is not fully closed (not applicable to vehicles in North America)
  • HVAC system demand is high
  • HVAC defrost has been selected
  • Battery charge is low
  • The learn procedure needs to be completed on the Battery Sensor Module
Likewise the engine will automatically restart if:
  • Driver door opened and driver seat belt unbuckled (not applicable to vehicles in North America)
  • Engine hood opened
  • Battery charge is low
  • HVAC demand increases
  • Vehicle speed increases
  • Brake booster vacuum has been reduced
  • Engine coolant temperature is greater than 125°C (257°F)
 

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Economy mode turned OFF by driverAutostop time exceeded 2 min
When the Stop/Start System has shut down the engine, and the ambient temperature is below 15°C (59°F), the ECM will activate the Stop/Start auxiliary relay which controls the electric engine coolant pump motor to continually circulate the engine coolant through the engine while the engine is off. This is to ensure the engine and passenger compartment temperature is maintained while off. Once the Stop/Start System has restarted the engine, the ECM will turn off the electric coolant pump motor, thus allowing the engines internal coolant pump to circulate the engine coolant. The Stop/Start System is automatically activated each time the ignition switch is turned on
<a id="d929e110">Autostop CriteriaThe ECM will send an Autostop state message to the body control module (BCM) and shut down the engine when all of the following criteria is met. The BCM will transmit the Autostop state message to the instrument cluster which will display the Autostop indicator in the tachometer display.
  • Economy mode turned ON
  • Initial minimum vehicle speed during drive cycle must be 19 km/h (12 MPH) or greater. Subsequent autostop minimum speed may vary from 2-10 km/h (1-6 MPH), depending on vehicle
  • Ambient and engine coolant temperature correlation meets specified values.
  • Ambient and transmission fluid temperature correlation meets specified values.
  • Hood switch status is closed
  • Driver door status is closed
  • Driver seat belt status is buckled
  • Brake booster vacuum is greater than 45 kPa (7 PSI)
  • Transmission gear selector is in the Drive position
  • Vehicle speed is less than 5 km/h (3 MPH)
  • Engine speed is below 1 500 RPM
  • Engine coolant temperature is less than 120°C (248°F)
  • Ambient temperature is greater than −10°C (14°F)
  • No A/C compressor request from HVAC (A/C or Defrost modes)
  • Battery voltage greater than 12 V
  • Battery state of charge greater than 75% (changes with state of health)
 

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<a id="d929e388">System Components
Engine Control Module (ECM) The engine control module (ECM) monitors the inputs from the engine coolant temperature (ECT) sensor, vehicle speed sensor (VSS), hood ajar switch, brake booster vacuum sensor, the clutch pedal position sensor, the manual transmission neutral position switch and engine speed to determine Autostart and Autostop conditions. The ECM also controls the auxiliary coolant pump motor.


Transmission Control Module (TCM) The transmission control module monitors the inputs from the transmission neutral safety switch to determine the driver selected gear. This information is transmitted to the ECM via serial data to support the Auto Stop Start algorithm.


Engine Coolant Temperature sensor The ECT sensor is used to determine engine operating temperature.


Intake Air Temperature Sensor The ECM uses this sensor to monitor ambient air temperature. If too cold, the Autostop will not occur.


Inside air temperature sensor The HVAC control module monitors the passenger compartment temperature sensor to determine the temperature inside the passenger compartment. The HVAC control module sends this temperature reading to the ECM on the data communication circuit. The ECM uses this temperature values to determine if a restart is requires based on the temperature inside the passenger compartment.


Vehicle speed sensor The vehicle speed sensor is used to determine vehicle speed. If vehicle speed is detected above a calculated value during an Autostop condition, the ECM will start the engine.


Hood Ajar Switch If the hood switch is in the open position, the vehicle will not Autostop. If the hood is opened during Autostop, the vehicle will automatically restart.


Brake Booster Vacuum Sensor The ECM monitors vacuum in order to ensure proper power assist for the brake pedal. If the ECM determines vacuum is too low, it will restart the engine.


Brake Pedal Position Sensor & Accelerator Pedal Position Sensor The ECM monitors both the brake pedal position sensor and the accelerator pedal position sensor to determine the level of activation for each. While the accelerator pedal is in it’s at rest position with no pressure applied by the operator, a partially depressed Brake pedal will cause the ECM to prepare the engine for an Autostop event. When the vehicle is in an auto stop event and the status of the brake pedal position sensor changes from meeting the autostop criteria to not meeting this criteria the engine will be restarted provided all of the other conditions to allow an autostart are met. If the Accelerator pedal is moved from its at rest position the vehicle will also enter an auto start event if all other conditions to support an autostart event, except for the brake pedal position, are met.


Transmission Gear Shift Position Switch The transmission gear shift position switch is used to determine if the transmission is in the proper state to allow an auto stop/start event. The ECM will not allow Autostop until the brake is engaged, the transmission is in the forward gear position and then the vehicle slows to below the minimum speed required to allow and autostop while meeting all of the other minimum criteria to support an autostop event.


Coolant Pump Motor The ECM will turn on the auxiliary coolant pump motor during Autostop to maintain engine operating temperature and also maintain HVAC temperature. Once the engine is running, the ECM will turn off the coolant pump motor.


Body Control Module (BCM) The body control module (BCM) is the master of the low speed communication bus and transfers the appropriate messages to the instrument cluster and the HVAC.


Battery Sensor Module The ECM monitors the intelligent battery sensor for battery state of current, state of health, and battery charge via the data communication bus. If the battery is determined to be in poor state of health or having a low charge, the ECM will not allow Autostop to occur.


Power Supply Transformer The DC to DC converter monitors battery voltage and will maintain operating voltage to the radio, instrument cluster and instrument panel displays. The DC to DC converter will provide a boosted voltage to sensitive loads during Autostart to ensure proper operation of the driver informational displays.


Driver Door Switch The BCM monitors the driver door switch at all times. The BCM will not allow Autostop if the door is ajar and will Autostart if the driver door is opened and the seat belt unbuckled during Autostop.


Driver Seat Belt Switch The BCM monitors the driver seat belt switch at all times. The BCM will Autostart if the seat belt is unbuckled and the driver door opened during Autostop.


Instrument Cluster In order to differentiate between a normal engine shut down (engine speed 0 RPM) and when the engine has been shut down by the Stop/Start System, the tachometer needle will rest at the Autostop indicator icon (500 RPM point) indicating the engine has been shut down by the Stop/Start System. Once the engine is restarted, the tachometer will function normally.
 

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:beer:whew ............:popcorn:
Thanks BigB12359 . . As always.. the most accurate info!

And . . thinking.. . Maybe a place to easily rig up an "Stop/Start" disable switch?

"- Hood Ajar Switch If the hood switch is in the open position, the vehicle will not Autostop. If the hood is opened during Autostop, the vehicle will automatically restart. "

Run some wires to the switch and simulate an "Open Hood" Condition? Any other negative effects of that? I can think of maybe one or two.
 
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