Grind noise heard on engine and felt at gas pedal on initial acceleration

[Areal1]

It's kind of violent. It's loud and can be felt in the gas pedal. Always makes me think my truck is having a transmission issue.

did you ever figure it out? I own a 2014 chevy impala and been searching all over for any info on this, its happening to me and i even replaced the transmission and its still there. Any help would be appreciated.
I know its 2 yrs later but this is the only discussion that Ive found that talks about it. Thanks

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[Marc S]

Did anyone who had this issue ever have luck at the dealer for this issue? I get it randomly but more often when turning onto certain streets or out of certain driveways. My dealer can’t recreate it on the streets around them.

 

[IdahoRanger]

The Ranger nanny taking control and using TC and ABS.

One turn here does it too.

 

[airline tech]

It's not the Traction Control that is causing it as its only looking at Wheel Speed offset (between the driven wheels vs non-driven wheels) (Slip)

The ESC (Electronic Stability Control) & RSC (Roll Stability Control) part of the Traction Control System factors in Steering Wheel Input
and uses the following sensors as inputs to the ABS Module, in the event that the ABS Module determines that the Vehicle is unstable from those inputs it activates the Solenoid Valves (internal to the HCU) to open and close and trips the pump motor on, this is the noise you hear, and the vibration can be felt at the gas pedal due to the HCU location.



Stability Control Sensors

The stability control sensors for the traction control and ESC functions consist of the yaw rate sensor, lateral accelerometer, longitudinal accelerometer and roll rate sensor. The sensors are housed in the RCM which sends sensor information to the ABS module over the HS-CAN2 . If any of the sensors are defective, a new RCM must be installed.

• The yaw rate sensor measures the yaw angle which is the difference between the direction the vehicle is pointing when cornering and the direction the vehicle is actually moving.
• The longitudinal accelerometer measures the acceleration and deceleration of the vehicle as it moves forward and backward.
• The lateral accelerometer measures the force created when a vehicle corners that tends to push a vehicle sideways.
• The roll rate sensor measures the rate of rotation of the vehicle along the centerline of the vehicle from front to back.

Lateral acceleration has 2 forms. The first is the centrifugal acceleration that is generated when the vehicle travels around in a circle. The second is the acceleration due to gravity. On level ground there is no lateral acceleration due to gravity. However, if the vehicle is parked sideways on a bank or incline, the sensor measures some lateral acceleration due to gravity, even though the vehicle is not moving.


and


Roll Stability Control (RSC)

The ABS module continuously monitors the vehicle motion relative to the intended course. This is done by using sensors to compare the steering wheel input, yaw rate sensor input, lateral accelerometer input and roll sensor input with the actual vehicle motion. The PSCM sends the steering wheel angle information to the ABS module over the HS-CAN2 . The RCM sends yaw rate sensor, lateral accelerometer and roll rate sensor information to the ABS module also over the HS-CAN2 . If the ABS module determines from the inputs the vehicle is becoming unstable, the ABS module modulates brake pressure to the appropriate brake calipers by opening and closing the appropriate solenoid valves inside the HCU while the hydraulic pump motor is activated. At the same time, the ABS module calculates how much engine torque reduction is required to help stabilize the vehicle and sends this torque reduction message to the GWM over the HS-CAN2 which relays the message to the PCM over the HS-CAN1 . The ABS module also sends a vehicle stability event message to the GWM over the HS-CAN2 which relays this message to the IPC over the HS-CAN3 . When the PCM receives the torque reduction message, it adjusts engine timing and decreases fuel injector pulses to reduce the engine torque to the requested level. When the IPC receives the vehicle stability event message, it flashes the stability-traction control indicator (sliding car icon).

Once the vehicle instability has been corrected, the ABS module returns the solenoid valves in the HCU to their normal position, deactivates the hydraulic pump motor and stops sending the traction event and torque reduction messages. The PCM returns engine timing and fuel injectors to normal operation and the IPC extinguishes the stability-traction control indicator (sliding car icon).

RSC does not operate with the transmission in REVERSE or with the transfer case in 4WD low. The ABS module disables RSC if there are any wheel speed sensor, stability sensor or steering angle sensor Diagnostic Trouble Codes (DTCs) present in the ABS module. If there is a communication error between the ABS module and the PSCM or the ABS module and the RCM , RSC also is disabled. When RSC is disabled, the ABS module sends a message to the GWM over the HS-CAN2 . The GWM relays this message to the IPC over the HS-CAN3 to illuminate the stability-traction control indicator (sliding car icon).



The ESC (Electronic Stability Control) is the same operation except it does not factor in the Roll Sensor Input

For Ref: RCM = Restraint Control Module

Note: The Torque Reduction in the above description, now I am not 100% sure but the noise or vibration felt in the gas pedal could possibly be the result of this. (IDK)

So, with this we can determine its normal operation of the (stability control) system however a faulty sensor giving false information could possibly be the issue is this occurs on every turn or slow and easy (grade matching) turns.
From what I understand of the posts so far (this event happens in a turn and uneven grades) and slow speeds

 

[4x4LAR]

Been having this issue as well on my 20’ Lariat 4x4 (27k miles) the last few months maybe 3-4 times now. Pull out of a driveway usually making a right and the dip from the slope of the drive way to the street with just a tad bit of acceleration and The TC light briefly flashes and I hear a grinding sound coming from below for 1-2 seconds. Taking it to the dealer tomorrow.

 

[Areal1]

I was having this issue on my 2014 impala limited and I finally fixed it so maybe this helps someone.
My sway bar is held down by two end bolts and two brackets with bushings that bolt into the frame, the left bracket's bolt wasn't secure due to it being stripped so I had to find a extra long bolt and hold it in place with a washer from the bottom (the hole goes into the frame and out the bottom) i just added 2 nuts and 3 washers to make up for the extra space left by the bolt. The issue has been gone ever since.

 

[Areal1]

Been having this issue as well on my 20’ Lariat 4x4 (27k miles) the last few months maybe 3-4 times now. Pull out of a driveway usually making a right and the dip from the slope of the drive way to the street with just a tad bit of acceleration and The TC light briefly flashes and I hear a grinding sound coming from below for 1-2 seconds. Taking it to the dealer tomorrow.

i posted this but just to make sure you see it before you go to the dealer (hopefully) heres what fixed it for me.
I was having this issue on my 2014 impala limited and I finally fixed it so maybe this helps someone.
My sway bar is held down by two end bolts and two brackets with bushings that bolt into the frame, the left bracket's bolt wasn't secure due to it being stripped so I had to find a extra long bolt and hold it in place with a washer from the bottom (the hole goes into the frame and out the bottom) i just added 2 nuts and 3 washers to make up for the extra space left by the bolt. The issue has been gone ever since.

 

[Areal1]

It's not the Traction Control that is causing it as its only looking at Wheel Speed offset (between the driven wheels vs non-driven wheels) (Slip)

The ESC (Electronic Stability Control) & RSC (Roll Stability Control) part of the Traction Control System factors in Steering Wheel Input
and uses the following sensors as inputs to the ABS Module, in the event that the ABS Module determines that the Vehicle is unstable from those inputs it activates the Solenoid Valves (internal to the HCU) to open and close and trips the pump motor on, this is the noise you hear, and the vibration can be felt at the gas pedal due to the HCU location.



Stability Control Sensors

The stability control sensors for the traction control and ESC functions consist of the yaw rate sensor, lateral accelerometer, longitudinal accelerometer and roll rate sensor. The sensors are housed in the RCM which sends sensor information to the ABS module over the HS-CAN2 . If any of the sensors are defective, a new RCM must be installed.

• The yaw rate sensor measures the yaw angle which is the difference between the direction the vehicle is pointing when cornering and the direction the vehicle is actually moving.
• The longitudinal accelerometer measures the acceleration and deceleration of the vehicle as it moves forward and backward.
• The lateral accelerometer measures the force created when a vehicle corners that tends to push a vehicle sideways.
• The roll rate sensor measures the rate of rotation of the vehicle along the centerline of the vehicle from front to back.

Lateral acceleration has 2 forms. The first is the centrifugal acceleration that is generated when the vehicle travels around in a circle. The second is the acceleration due to gravity. On level ground there is no lateral acceleration due to gravity. However, if the vehicle is parked sideways on a bank or incline, the sensor measures some lateral acceleration due to gravity, even though the vehicle is not moving.


and


Roll Stability Control (RSC)

The ABS module continuously monitors the vehicle motion relative to the intended course. This is done by using sensors to compare the steering wheel input, yaw rate sensor input, lateral accelerometer input and roll sensor input with the actual vehicle motion. The PSCM sends the steering wheel angle information to the ABS module over the HS-CAN2 . The RCM sends yaw rate sensor, lateral accelerometer and roll rate sensor information to the ABS module also over the HS-CAN2 . If the ABS module determines from the inputs the vehicle is becoming unstable, the ABS module modulates brake pressure to the appropriate brake calipers by opening and closing the appropriate solenoid valves inside the HCU while the hydraulic pump motor is activated. At the same time, the ABS module calculates how much engine torque reduction is required to help stabilize the vehicle and sends this torque reduction message to the GWM over the HS-CAN2 which relays the message to the PCM over the HS-CAN1 . The ABS module also sends a vehicle stability event message to the GWM over the HS-CAN2 which relays this message to the IPC over the HS-CAN3 . When the PCM receives the torque reduction message, it adjusts engine timing and decreases fuel injector pulses to reduce the engine torque to the requested level. When the IPC receives the vehicle stability event message, it flashes the stability-traction control indicator (sliding car icon).

Once the vehicle instability has been corrected, the ABS module returns the solenoid valves in the HCU to their normal position, deactivates the hydraulic pump motor and stops sending the traction event and torque reduction messages. The PCM returns engine timing and fuel injectors to normal operation and the IPC extinguishes the stability-traction control indicator (sliding car icon).

RSC does not operate with the transmission in REVERSE or with the transfer case in 4WD low. The ABS module disables RSC if there are any wheel speed sensor, stability sensor or steering angle sensor Diagnostic Trouble Codes (DTCs) present in the ABS module. If there is a communication error between the ABS module and the PSCM or the ABS module and the RCM , RSC also is disabled. When RSC is disabled, the ABS module sends a message to the GWM over the HS-CAN2 . The GWM relays this message to the IPC over the HS-CAN3 to illuminate the stability-traction control indicator (sliding car icon).



The ESC (Electronic Stability Control) is the same operation except it does not factor in the Roll Sensor Input

For Ref: RCM = Restraint Control Module

Note: The Torque Reduction in the above description, now I am not 100% sure but the noise or vibration felt in the gas pedal could possibly be the result of this. (IDK)

So, with this we can determine its normal operation of the (stability control) system however a faulty sensor giving false information could possibly be the issue is this occurs on every turn or slow and easy (grade matching) turns.
From what I understand of the posts so far (this event happens in a turn and uneven grades) and slow speeds

I was having this issue on my 2014 impala limited and I finally fixed it so maybe this helps someone.
My sway bar is held down by two end bolts and two brackets with bushings that bolt into the frame, the left bracket's bolt wasn't secure due to it being stripped so I had to find a extra long bolt and hold it in place with a washer from the bottom (the hole goes into the frame and out the bottom) i just added 2 nuts and 3 washers to make up for the extra space left by the bolt. The issue has been gone ever since.

 

[Areal1]

Did you guys ever figure this out or did the phenomenon just resolve itself? I think I've got the same thing going on. It's happened twice. It's happened at low speeds both times abruptly. There is a pretty significant audible and tactile buzzing/vibration felt in the gas pedal that lasts 1.5-2 seconds.

The 2nd time it happened I noticed there was a clicking noise at the end of the buzzing interval and the RPMs dropped by a few hundred. I did not change accelerator pedal position at all during the buzzing interval. I did not have the gear indicator available so I don't know if the RPM drop was resultant of a downshift or just a RPM drop in the same gear.

I'm very relunctanty thinking that a dealer visit may be in order but I'm not sure a TCM (is that what Ford calls it?) reflash is available for 2021s.

I was having this issue on my 2014 impala limited and I finally fixed it so maybe this helps someone.
My sway bar is held down by two end bolts and two brackets with bushings that bolt into the frame, the left bracket's bolt wasn't secure due to it being stripped so I had to find a extra long bolt and hold it in place with a washer from the bottom (the hole goes into the frame and out the bottom) i just added 2 nuts and 3 washers to make up for the extra space left by the bolt. The issue has been gone ever since.

 

[4x4LAR]

i posted this but just to make sure you see it before you go to the dealer (hopefully) heres what fixed it for me.
I was having this issue on my 2014 impala limited and I finally fixed it so maybe this helps someone.
My sway bar is held down by two end bolts and two brackets with bushings that bolt into the frame, the left bracket's bolt wasn't secure due to it being stripped so I had to find a extra long bolt and hold it in place with a washer from the bottom (the hole goes into the frame and out the bottom) i just added 2 nuts and 3 washers to make up for the extra space left by the bolt. The issue has been gone ever since.

Hey thanks yeah I’m gonna lift the truck up first and see if anything’s loose include those end bolts you’re talking about.

 

[Areal1]

did you figure it out? i searched everywhere for a solution but never found one, i seen this thread and never got a answer until i figured it out after i had to replace my struts, the sway bar was free on one side and it was scraping the frame when the wheel was turned and when going over humps. hopefully it saves someone some money.

 

[airline tech]

did you figure it out? i searched everywhere for a solution but never found one, i seen this thread and never got a answer until i figured it out after i had to replace my struts, the sway bar was free on one side and it was scraping the frame when the wheel was turned and when going over humps. hopefully it saves someone some money.

The (grinding noise) is actually the ABS Pump kicking on - and it is cycling the solenoid valves in the HCU on the wheel the system is sensing (spinning faster than the rest) - so it is applying pulsating brake pressure (automatically) - hence the momentary flash of the TC Indicator.
Traction Control and Stability Control - tie together so sensor inputs cause the ABS to activate. (all the holes in the cheese line up) Turn and Dip and Accelerate

The five inputs that tie in are:
Steering Wheel Input
Yaw Rate
Longitudinal Accelerometer
Lateral Accelerometer
Roll Rate

 

[Cabose-1]

Power steering??

 

[Areal1]

The (grinding noise) is actually the ABS Pump kicking on - and it is cycling the solenoid valves in the HCU on the wheel the system is sensing (spinning faster than the rest) - so it is applying pulsating brake pressure (automatically) - hence the momentary flash of the TC Indicator.
Traction Control and Stability Control - tie together so sensor inputs cause the ABS to activate. (all the holes in the cheese line up) Turn and Dip and Accelerate

The five inputs that tie in are:
Steering Wheel Input
Yaw Rate
Longitudinal Accelerometer
Lateral Accelerometer
Roll Rate

my Stabilitrack, ABS and Traction lights all were coming on as well whenever the noise happened, im just glad it wasnt a major thing like most.

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