V6 to v4 disable by unplugging afm oil pressure sensor

[Homer1952]

49 minutes ago, hwycruiser said:

GM engine guys might consider "long term effects" to be 100k miles. I consider them 200k to 300k miles. I don't see any benefit of going to v4. I don't care about the loss of mpg under light throttle or coasting. 

I am hoping someone can post a pic of location of afm solenoid wiring harness connector.

Where did you get that data?  I retired 10 years ago & we didn't have that mentality.

[hwycruiser]

51 minutes ago, Homer1952 said:

Where did you get that data?  I retired 10 years ago & we didn't have that mentality.

Why don't you enlighten us what is long term by GM standards ?  AFM did not fare well by some accounts 10 years ago. Sure it has gotten better since then but I don't see why I can't turn it off without hurting feelings on this board

[Homer1952]

  Ahhh. The answer the question with a question trick!  I'll tell you, if you tell me first.  What data do you have that the current AFM is unreliable?  And you did not hurt my feelings.  I am just trying to understand your fear.

 

BTW, a friend of mine got a 2018 Buick with ASS (AutoStopStart) and he is like you, in that he is worried about the reliability of the system.  Nothing I could say to him would convince him that the system was designed with the 98% user in mind.

 

I, too, plan on keeping my Acadia for a long time and have no fear over AFM.  My plan is to keep it for 10 years or more just like I owned my Pontiac Torrent GXP.  It was still near mint when I sold it & the guy who owns it now said it has been trouble free.  It only had 110k miles on it when I sold it.

 

BTW, I kicked the butt of a new Honda Pilot the other day with my V6 Acadia.

[KARNUT]

  Ahhh. The answer the question with a question trick!  I'll tell you, if you tell me first.  What data do you have that the current AFM is unreliable?  And you did not hurt my feelings.  I am just trying to understand your fear.
 
BTW, a friend of mine got a 2018 Buick with ASS (AutoStopStart) and he is like you, in that he is worried about the reliability of the system.  Nothing I could say to him would convince him that the system was designed with the 98% user in mind.
 
I, too, plan on keeping my Acadia for a long time and have no fear over AFM.  My plan is to keep it for 10 years or more just like I owned my Pontiac Torrent GXP.  It was still near mint when I sold it & the guy who owns it now said it has been trouble free.  It only had 110k miles on it when I sold it.
 
BTW, I kicked the butt of a new Honda Pilot the other day with my V6 Acadia.

Wait till he finds out that the battery cost 400$ and he has two. That’s a lot of gas. Unless they made changes that’s what it cost my son on his two year old Malibu.


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[hwycruiser]

This is not about Honda v gmc. I don't like Honda pilot. I love gmc acadia. I just want to know where is that darn harness lol.

Want to keep this one for 25 years atleast.

[newdude]

On ‎3‎/‎1‎/‎2019 at 1:28 PM, hwycruiser said:

Plan on keeping the car for 300k miles if I can !  Not sure how the 2 cylinders deactivated will fair in the long run. Range tech support said 19 Acadia might run rough after install of their product as reported back to them from some users. I have 350 miles on it. Pretty seamless v6 to v4. Just long term concerns. 

 

The AFM in the LGX V6 (the engine in your car) is somewhat different than the truck engine AFM.  The trucks being pushrod use "trick" hydraulic roller lifters with springs in them.  When oil pressure is applied to the locking pin, the lifter collapses on itself as it follows the camshaft.

 

The V6 is rocker arm based, and uses different oil controlling, etc. than the truck application. 

 

On ‎3‎/‎1‎/‎2019 at 1:39 PM, hwycruiser said:

I will try the sports mode in manual.

Have heard if you go to highest gear 6 then 5 then 6 it might stay in v6.

Still would like to where the harness is located for the afm solenoid with pic possibly.

 

M5/L5 will disable.  M6/L6 will activate AFM. 

 

Unpluging any of the AFM components WILL place the vehicle into Reduced Power Mode per the diagnostics. 

 

If your heart is truly set on disabling it, aftermarket support will be the only way (Range, tuning, etc.).  That all comes down to what GM ECM the car uses, as new ones have rolling encryption and are hard to crack. 

Edited March 2, 2019 by newdude

[hwycruiser]

What does reduce power mode actually imply. It's in v6 by default.  

 

Will try the l5.  I coast to stop signs. Hopefully I won't see v4 on dashboard.

[hwycruiser]

I just tried putting it in L5. V4 mode  kicks in on coasting downhill or to a stop sign.  

[Homer1952]

6 hours ago, KARNUT said:

Wait till he finds out that the battery cost 400$ and he has two. That’s a lot of gas. Unless they made changes that’s what it cost my son on his two year old Malibu.


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He tells me his Buick Regal only has one AGM Battery.  Still, to your point, AGM's are more expensive than standard batteries.  - Bob

[KARNUT]

He tells me his Buick Regal only has one AGM Battery.  Still, to your point, AGM's are more expensive than standard batteries.  - Bob

Imagine his surprise when he finds out there are two. I just looked it up.


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[hwycruiser]

I drove on the highway in L6 and sport mode. Speeds were 60 to 75 mph. Afm never came on. I got a best  30.2 mpg as shown on dashboard. In town it comes on sparingly. I am startiing to think it is a marketing tool for sounding sophisticated to the average buyer. Too much complexity too little gain in my opinion on a v6.

 

Still waiting for someone to tell me the location of the afm solenoid wiring harness

[KARNUT]

I drove on the highway in L6 and sport mode. Speeds were 60 to 75 mph. Afm never came on. I got a best  30.2 mpg as shown on dashboard. In town it comes on sparingly. I am startiing to think it is a marketing tool for sounding sophisticated to the average buyer. Too much complexity too little gain in my opinion on a v6.
 
Still waiting for someone to tell me the location of the afm solenoid wiring harness [emoji4]

Wait a minute GM has a sport mode? What does it do.


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[hwycruiser]

I got this from this site only

Unplugging the solenoid harness might inhibit afm activation. It is for older v8.

 

Cylinder Deactivation (Active Fuel Management) System Description

 

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 cylinders 4 and 6 on the right bank, switching to a V4 mode. The engine will operate on 8 cylinders, or V8 mode, during engine starting, engine idling, and medium to heavy throttle applications.

 

When commanded ON, the ECM will determine what cylinder is firing, and begin deactivation on the next closest deactivated cylinder in firing order sequence. The Gen IV engine has a firing order of 1-8-7-2-6-5-4-3. If cylinder number 1 is on its combustion event when cylinder deactivation is commanded ON, the next cylinder in the firing order sequence that can be deactivated is cylinder number 7. If cylinder number 5 is on its combustion event when cylinder deactivation is commanded ON, then the next cylinder in the firing order sequence that can be deactivated is cylinder number 4.

 

Cylinder deactivation is accomplished by not allowing the intake and exhaust valves to open on the selected cylinders by using special valve lifters. The deactivation lifters contain spring loaded locking pins that connect the internal pin housing of the lifter to the outer housing. The pin housing contains the lifter plunger and pushrod seat which interfaces with the pushrod. The outer housing contacts the camshaft lobe through a roller. During V8 mode, the locking pins are pushed outward by spring force, locking the pin housing and outer housing together causing the lifter to function as a normal lifter. When V4 mode is commanded ON, the locking pins are pushed inward with engine oil pressure directed from the valve lifter oil manifold (VLOM) assembly solenoids. When the lifter pin housing is unlocked from the outer housing, the internal pin housing will remain stationary, while the outer housing will move with the profile of the camshaft lobe, which results in the valve remaining closed. One VLOM solenoid controls both the intake and exhaust valves for each deactivating cylinder. There are 2 distinct oil passages going to each cylinder deactivation lifter bore, one for the hydraulic lash-adjusting feature of the lifter, and one for controlling the locking pins used for cylinder deactivation.

 

Although both intake and exhaust valve lifters are controlled by the same solenoid in the VLOM, the intake and exhaust valves do not become deactivated at the same time. Cylinder deactivation is timed so that the cylinder is on an intake event. During an intake event, the intake cam lobe is pushing the valve lifter upwards to open the intake valve against the force of the valve spring. The force exerted by the valve spring is acting on the side of the lifter locking pins, preventing them from moving until the intake valve has closed. When the intake valve lifter reaches the base circle of the camshaft lobe, the valve spring force is reduced, allowing the locking pins to move, deactivating the intake valve. However, when cylinder deactivation is commanded ON, the exhaust valve for the deactivated cylinder is in the closed position, allowing the locking pins on the valve lifter to move immediately, and deactivate the exhaust valve.

 

By deactivating the exhaust valve first, this allows the capture of a burnt air/fuel charge or exhaust gas charge in the combustion chamber. The capture of exhaust gases in the combustion chamber will contribute to a reduction in oil consumption, noise and vibration levels, and exhaust emissions when operating in V4 mode. During the transition from V8 to V4 mode, the fuel injectors will be turned OFF on the deactivated cylinders. The ignition system secondary voltage or spark is still present across the spark plug electrodes on the deactivated cylinders. If all enabling conditions are met and maintained for cylinder deactivation operation, the ECM calibrations will limit cylinder deactivation to a cycle time of 10 minutes in V4 mode, and then return to V8 mode for 1 minute.

 

Switching between V8 and V4 mode is accomplished in less than 250 milliseconds, making the transitions seamless and transparent to the vehicle operator. The 250 milliseconds includes the time for the ECM to sequence the transitions, the response time for the VLOM solenoids to energize, and the time for the valve lifters to deactivate, all within 2 revolutions of the engine crankshaft.

 

The cylinder deactivation system consists of the following components:

 

• The VLOM assembly

 

• Eight special valve lifters, 2 per deactivating cylinder

 

• The engine oil pressure regulator valve for cylinder deactivation operation

 

• Gen IV cylinder deactivation engine block

 

• The ECM

 

Valve Lifter Oil Manifold (VLOM) Assembly

The cylinder deactivation system uses an electro-hydraulic actuator device called the valve lifter oil manifold (VLOM) assembly. The VLOM is bolted to the top of the engine valley, below the intake manifold assembly. The VLOM consists of 4 electrically operated Normally Closed Solenoids. Each solenoid controls the application of engine oil pressure to the intake and exhaust valve lifters on the cylinders selected to deactivate. Engine oil pressure is routed to the VLOM assembly from a passage on the rear of the cylinder block.

 

All 4 VLOM solenoids are connected in parallel to a fused ignition 1 voltage circuit, supplied by the powertrain relay. The ground or control circuit for each solenoid is connected to the engine control module (ECM).

 

When all enabling conditions are met for cylinder deactivation, the ECM will ground each solenoid control circuit in firing order sequence, allowing current to flow through the solenoid windings. With the coil windings energized, the solenoid valve opens, redirecting engine oil pressure through the VLOM into 8 separate vertical passages in the engine lifter valley. The 8 vertical passages, 2 per cylinder, are connected to the valve lifter bores of the cylinders to be deactivated. When vehicle-operating conditions require a return to V8 mode, the ECM will turn OFF the control circuit for the solenoids, allowing the solenoid valves to close. With the solenoid valves closed, engine oil pressure in the control ports is exhausted through the body of the solenoids into the engine block lifter valley. The housing of the VLOM incorporates several bleeds in the oil passages to purge any air trapped in the VLOM or engine block.

 

To control any contamination to the hydraulic circuits, a small replaceable oil screen is located in the VLOM oil inlet passage, below the oil pressure sensor. The oil pressure sensor is a 3-wire sensor which provides oil pressure information to the ECM.

 

During service, use extreme care in keeping the VLOM assembly free of any contamination or foreign material.

 

Engine Control Module (ECM)

The engine control module (ECM) is responsible for the management and control of all engine functions. Each ECM comes equipped with a specific set of software/calibrations designed for that engine and vehicle application. The ECM will determine engine operating parameters, based upon information from a network of switches, sensors, modules and communication with other controllers located throughout vehicle. Internal to the ECM is an integrated circuit device called a low-side driver. The low-side driver is designed to operate internally, like an electronic switch. An individual low-side driver controls each valve lifter oil manifold (VLOM) solenoid. When enabling conditions for V4 mode are met, the ECM will command the low-side driver to ground each VLOM solenoid control circuit, in firing order sequence. Internal to the low-side driver is a fault detection circuit, which monitors the solenoid control circuit for an incorrect voltage level. If an incorrect voltage level, such as an open, high resistance, or short to ground, is detected, the low-side driver, along with the fault detection circuit, will communicate the condition to the central processor in the ECM. The ECM will then command a return to V8 mode, set a corresponding DTC, and illuminate the malfunction indicator lamp (MIL) on the instrument panel.

 

Cylinder Deactivation Inhibit Reasons

Listed below are the powertrain conditions that will inhibit 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, electronic throttle control

 

• Accelerator pedal position too high, electronic throttle control

 

• 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

 

• Maximum V4 mode 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, electronic throttle control

 

• Brake torque management active

 

• Axle torque limiting active

 

• Engine metal over temperature protection active

 

• Catalytic converter over temperature protection active

 

• Piston protection active, knock detected

 

• Hot coolant mode active

 

• Engine over speed protection active

 

• Fault Active or Fault Pending--cylinder deactivation is disabled for the following faults:

 

- Brake Booster Vacuum Sensor

 

- Manifold Absolute Pressure Sensor

 

- Engine Oil Pressure Sensor

 

- Engine Coolant Temperature Sensor

 

- Vehicle Speed Sensor

 

- Crankshaft Position Sensor

 

- Engine Misfire Detected

 

- Cylinder Deactivation Solenoid Driver Circuit

 

The scan tool output control is used to deactivate half of the engine cylinders, V4 mode, by commanding all of the solenoids ON, or deactivate one cylinder switching to a V7 mode, by commanding ON one solenoid. Listed below are the powertrain conditions that will inhibit V4 mode, or V7 mode, with the engine running, while using the scan tool output control function:

 

• Engine speed out of range

 

• Manifold absolute pressure (MAP) sensor fault

 

• Accelerator pedal position too high, electronic throttle control

 

• Piston protection active, knock detected

 

• Engine oil temperature out of range

 

• Engine oil pressure out of range

 

• Engine oil aeration present

 

• Engine metal over temperature protection active

 

• Accelerator pedal position rate of increase too high, electronic throttle control

 

• Cylinder deactivation solenoid driver circuit fault

 

• Engine coolant temperature sensor fault

 

• Catalytic converter over temperature protection active

 

• Brake booster vacuum pressure low

 

• Brake Booster Vacuum Pressure Sensor Fault

 

• Axle torque limiting active

 

• Brake torque management active

 

• Vehicle speed sensor fault

 

• Engine coolant temperature too high

 

• Engine not running

 

• Vehicle speed not zero

 

• Engine coolant temperature low

 

• Reduced Engine Power Active, electronic throttle control

 

• Transmission gear incorrect

 

• Transmission range incorrect

 

• Ignition voltage out of range

 

• Maximum V4 mode time exceeded

 

Listed below are the powertrain conditions that will inhibit a cylinder deactivation solenoid from being energized, with the ignition ON and the engine OFF, while using the scan tool output control function:

 

• Engine speed not zero

 

• Vehicle speed not zero

 

• Transmission not in park or neutral

 

• Ignition voltage out of range

 

[newdude]

From the owners manual:

On ‎3‎/‎2‎/‎2019 at 2:46 PM, hwycruiser said:

What does reduce power mode actually imply. It's in v6 by default.  

 

Will try the l5.  I coast to stop signs. Hopefully I won't see v4 on dashboard.

 

More description on Engine Reduced Power:

 

Quote

 

Engine Control Module (ECM) Commanded Reduced Engine Power

Under certain conditions the engine control module may limit engine power by reducing engine torque and, for some vehicles, fuel pressure as well. For most, but not all of the conditions, the engine control module will illuminate the reduced engine power lamp on the instrument cluster. If equipped with the driver information center feature, a reduced engine power message may be displayed as well. A DTC may not be set.

A repair may not be necessary. Observe the scan tool Reduced Engine Power History parameter or refer to K20 Engine Control Module: Scan Tool Information to determine the reason for the reduced engine power event.

 

Verify or inspect for the following:

• Vehicle being driven inappropriately. Towing heavy loads up an incline for an extended period of time or operating the vehicle at sustained, excessively high engine speeds may cause the engine oil or coolant to overheat. Inspect the airflow passageways in front of the engine for obstructions and clear away any debris or foreign material that is found. If no obstructions are found, review approved driving habits with the customer. The customer may need to operate the vehicle at a higher engine speed to improve cooling system performance, or, at a slower engine speed to reduce engine load.
• Temporary reduced engine power. Under extremely cold ambient temperatures some SIDI equipped vehicles may experience ECM commanded reduced engine power for a few minutes during engine warm-up. This would be a normal condition, noticeable only at wide open throttle, and the reduced engine power lamp would not be illuminated.
• Reduced engine power may be due to OnStar® remote command. Verify the vehicle is not in the OnStar® initiated Stolen Vehicle Slowdown mode—Refer to Remote Vehicle Speed Limiting Description and Operation and OnStar Stolen Vehicle Slowdown Active.
• A cooling fan condition which may cause the engine coolant or oil to overheat. Refer to Cooling Fan Description and Operation and Cooling System Description and Operation to verify correct operation of the cooling fan.

 

 

Acadia AFM inhibits:

 

Quote

 

Cylinder deactivation may be inhibited for many reasons including the following:

• Engine coolant temperature out of range for cylinder activation
• Engine vacuum out of range
• Brake booster vacuum out of range
• Transmission gear incorrect or shift in progress
• Accelerator pedal out of range or rate of pedal application to fast
• Engine oil pressure and temperature out of range
• Engine speed out of range
• Vehicle speed out of range
• Minimum time in V6 mode not met
• Maximum V4 mode time exceeded
• Decel fuel cutoff is active
• Reduced engine power is active
• Torque management is active
• Catalytic converter over temperature protection is active
• Piston protection is active, knock detected
• Cylinder deactivation solenoid driver circuit faults

 

 

Unplugging ANY of the AFM components would cause a cylinder deactivation circuit fault, set codes, and place the engine into reduced power mode. 

 

AFM DTC's that would arise, and what happens if they do:

 

 

Quote

 

Actions Taken When the DTC Sets

DTCs listed in the DTC Descriptor Category = Type B DTC — Exceptions listed below

DTC P06DB, P06DE = Type A DTC

• Engine Oil Pressure Control Solenoid Valve = Off
• Reduced Engine Power = Active

 

 

Unplugging ANY would get you a P06DA Engine Oil Pressure Control Solenoid Valve Control Circuit, and a P06DB Engine Oil Pressure Control Solenoid Valve Control Circuit Low Voltage at a minimum.  The P06DB will be the one that places it into Reduced Engine Power as it is a Type A DTC (top of the chain to set CEL or reduced power). 

 

Not really sure I can explain this anymore...

Edited March 4, 2019 by newdude

[hwycruiser]

Okay thanks newdude.

I will unplug them and verify.

 

In L5 the afm still kicks on.

 

What about unplugging the brake vacuum sensor ?