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Discussion Starter #1
Does anyone know, if any of the aftermarket companies will come out with some sort of "Aftermarket Modification" that would let the driver know when he/she is in 4 cyl. mode and when they are in 8 cyl. mode?

I know gas mileage isn't the primary concern of this car, but I know in the Impala SS (5.3 liter V8), they have a factory setting that lets the driver what cylinder mode they are in.

Any thoughts? (Has this type of mod been done in other vehicles already?)

Thanks! :popcorn2:
 

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Stryker
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Does anyone know, if any of the aftermarket companies will come out with some sort of "Aftermarket Modification" that would let the driver know when he/she is in 4 cyl. mode and when they are in 8 cyl. mode?

I know gas mileage isn't the primary concern of this car, but I know in the Impala SS (5.3 liter V8), they have a factory setting that lets the driver what cylinder mode they are in.

Any thoughts? (Has this type of mod been done in other vehicles already?)

Thanks! :popcorn2:
i would think it would let you know, if not you would probably be able to tell using your "car sense":driving:

unless you are wanting to manually turn it on and off
 

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Working for GM I know that if you have this AFM engine the instrument panel will display if your in V4 or V8 mode by simpling requesting the information by going through the displays from DIC.
 

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Discussion Starter #4
I hope so. The Grand Prix GXP has active fuel management with nothing in their DIC telling the driver 4 C mode vs. 8 C mode.
 

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I hope so. The Grand Prix GXP has active fuel management with nothing in their DIC telling the driver 4 C mode vs. 8 C mode.
Probably depends on the options I know the Impala SS will show it if you hit the button on right of the IPC which displays, MPG, oil life, tire pressure. You have to be driving to see it active normally around 30 MPH cruising it will display V4 Mode or V8 Mode. Same set up as the GMT 900's.
 

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Probably depends on the options I know the Impala SS will show it if you hit the button on right of the IPC which displays, MPG, oil life, tire pressure. You have to be driving to see it active normally around 30 MPH cruising it will display V4 Mode or V8 Mode. Same set up as the GMT 900's.
Does it activate based on just the load level or speed and load level? In other words, do you have to be going a certain speed (30mph?) for it to activate? I'm just wondering whether it'll idle all cylinders or four.
 

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I believe it is based on speed (30+?) and load. I am pretty sure it fires on all eight at idle.

The I saw a G8 GT vs. Charger R/T compo (C&D? LLN?) that implied that there was no display in the G8. Or the reviewers couldn't find it. :drink:
 

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I've had DOD for the last three years on the GP GXP. Quite frankly, worrying about having an indicator to tell you when you're in V4 or V8 mode is a waste of time. The indicator is just another gimmick that really does nothing.

Whenever you accelerate at all, including climbing really small grades, you will be in V8 mode. Period. Low speed and idle will also be in V8 mode. V4 only happens when cruising at a stable speed above approx 60 kmh (third or fourth gear in the GP) or when going down hill.

DOD really is transparent unless you muck with the torque converter clutch settings.

Find something else to obsess about :D

 

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Does it activate based on just the load level or speed and load level? In other words, do you have to be going a certain speed (30mph?) for it to activate? I'm just wondering whether it'll idle all cylinders or four.
Depends on the driving situation or load as you describe it. The AFM is reading the angle position of the throttle to determine whenever to go in V4 or V8 mode. 30 Mph without giving it gas or cruising will put it in V4 mode. At start up it goes into V8 during idle it will toggle it back and fourth. As for the a/c being on I haven't tried that out yet but I believe it goes into v8 mode because the load of what the a/c compressor is doing to the engine.
 

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Depends on the driving situation or load as you describe it. The AFM is reading the angle position of the throttle to determine whenever to go in V4 or V8 mode. 30 Mph without giving it gas or cruising will put it in V4 mode. At start up it goes into V8 during idle it will toggle it back and fourth...
I'm not sure if you had a runon sentence, but AFM V4 mode will not activate during idle. It will remain in V8 mode the whole time. You may not have meant that, but it kinda sounded that way in your sentence.

Chip
 

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noobie
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can you guys really feel when its in V8 or V4 mode???

i currently drive dodge truck with hemi. it has MDS. i do lots of traveling , so far, i can't tell the difference.
 

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I have a 5 page Service Information bulletin that you can get from your Pontiac service department. Ask for them to print out document ID# 1959166.

Here are some comments:

"To provide maximum fuel economy under light load driving conditions, the Engine Control Module (ECM) will command the cylinder deactivation system ON to deactivate engine cylinders 1 and 7 on the left bank and 4 and 6 on the right bank, switching to a V4 mode. The engine will operate on 8 cylinders during engine starting, engine idling and medium to heavy throttle applications."

There follows a detailed description of the system called the VLOM or Valve Lifter Oil Manifold solenoids that control valves on the chosen cylinders -- too detailed to go into here.

Then this:

"Switching between V8 and V4 mode is accomplished in less than 250 milliseconds, making transitions seemless and transparent to the vehicle operator."

Then more details on the VLOM and ECM cooperation, and then a list of the powertrain conditions that will inhibit (turn off) V4 mode, while operating under light load driving conditions:
Engine manifold vacuum low
Brake booster vacuum pressure low
Accelerator pedal position rate of increase too high
Accelerator pedal position too high
Ignition voltage out of range
Engine oil pressure out of range
Engine oil temperature out of range
Engine RPM out of range
Transmission gear incorrect
Transmission range incorrect
Transmission gear shift in progress
All cylinders activated via scan tool output control
Minimum time in V8 mode not met
(Note: if all enabling conditions for V4 mode are met and maintained, the ECM will limit cylinder deactivation to 10 minutes in V4 mode, then return to V8 mode for 1 minute)
Maximum V4 time exceeded
Engine oil aeration present
Decel fuel cutoff active
Fuel shut-off timer active
Minimum heater temp low (HVAC system)
Reduced engine power active (I call this "limp home mode")
Brake torque management active
Axle torque limiting active
Engine metal overtemperature protection active
Catalytic converter over temperature protection active
Piston protection active - knock detected (regular fuel, or ...?)
Hot coolant mode active
Engine overspeed protection active
Fault active or fault pending for the following: Brake booster vacuum sensor, manifold absolute pressure (MAP) sensor, engine oil pressure sensor, engine coolant temperature sensor, vehicle speed sensor, crankshaft position sensor, engine misfire detected, cylinder deactivation solenoid driver circuit

There is no mention of a DIC indicator on the dash for V4/V8 mode. It will light the Malfunction Indicator Lamp (MIL) if the VLOM sees an error.
 

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can you guys really feel when its in V8 or V4 mode???

i currently drive dodge truck with hemi. it has MDS. i do lots of traveling , so far, i can't tell the difference.
I've had DOD for the last three years on the GP GXP. Quite frankly, worrying about having an indicator to tell you when you're in V4 or V8 mode is a waste of time. The indicator is just another gimmick that really does nothing.

Whenever you accelerate at all, including climbing really small grades, you will be in V8 mode. Period. Low speed and idle will also be in V8 mode. V4 only happens when cruising at a stable speed above approx 60 kmh (third or fourth gear in the GP) or when going down hill.

DOD really is transparent unless you muck with the torque converter clutch settings.

Find something else to obsess about .
Same experience here. Even after a tune (which shouldn't effect it anyway).
 

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Discussion Starter #18
I heard in the Impala SS with the 5.3 and indicator light. If you lock in the cruise control at about 80mph you will be operating in 8 cyl mode. But if you hit the "minus" 1 mph a time or two, you can get the car to go into 4 cyl. mode.

For highway driving on longer trips, this would be beneficial if one has to "trick" the car into going into 4 cyl. mode.

: )
 

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As far as I can tell there is no indicator lamp. I drove the vehicle 45 miles on cruise at 65mph and no indicator lamps came up. Just showing almost 23mpg :cool:
 

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I found this pic on a Holden site.



Does the G8GT have an "Engineering Mode" which can be seen on the DIC? On this particular Holden(L98) although it doesn't come with AFM it shows that it can be enabled/disabled. Maybe through that you can activate the indicator if there is one idk.
 
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