Rough Idle In Drive – 2014-2019 Cadillac Chevrolet GMC

ulletin
Bulletin No.: 17-NA-166
Date: June, 2020

TECHNICAL

Subject: Rough Idle in Drive

This Bulletin replaces PIP5211F. Please discard PIP5211F.

Brand:

Cadillac

Chevrolet

GMC GMC

Model:

Escalade Models Silverado Silverado LD Suburban
Tahoe Sierra
Sierra Limited Yukon Models
Model Year: from to
2015 2019
2014 2018
2019 2019

2015 2019

2014 2018
2019 2019
2015 2019
VIN:
from to

– –
Engine:

L83, L86, LV1, LV3 (4.3L,
5.3L, 6.2L)
Transmission:

All

Involved Region or Country

Condition

North America, Argentina, Brazil, China, Chile, Ecuador, Germany, Israel, Japan, Korea, Kuwait,
Philippines, Peru, Switzerland and Saudi Arabia.
Some customers may comment about a rough idle and/or vibration at idle in Drive.
This condition may be most noticeable following extended driving, after hard acceleration, while
idling at a stop in Drive.
May feel like a lopey or lumpy idle, or may be described as a low idle.
This condition will not be present in Park or Neutral. (There have been a few cases for rough idle
in Reverse.)
Note: There will not be any DTCs with this concern.

Cause

This concern may be caused by ground out (1) within one or both engine mounts.

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Correction

Important: Familiarize yourself with this entire bulletin before proceeding to ensure you are
diagnosing and focusing on the correct issue by frequency measured with Pico scope.
Perform PICO analysis, refer to the Service Procedure section below.
⇒ If the rough idle / vibration concern frequency is E1.5 in the horizontal / lateral direction
with Pico sensor mounted in seat track as indicated below – continue with steps to install updated
design engine mounts and settle both engine and trans mounts to reduce amplitude (mg) / eliminate
ground out
within the engine mounts for vehicles built prior to engine mount breakpoint. For vehicles built
after breakpoint, follow Shimming Procedure for Engine Mount Vibration/Grounding after Mount
Replacement.
Important: The updated engine mounts are designed to reduce internal ground out, primarily E1.5.
These mounts along with engine and trans mount settling will typically reduce amplitude at the seat
track to 2 mg or less.
Note: The 6.2L engine has a characteristic E1 which can be felt and may be described as a lopey
idle. V-8 engine firing frequency produces E4 which will typically be very low frequency at the
seat track. Do not confuse 6.2L E1 characteristic (not caused by mount ground-out), with E1.5
normal idle characteristics being transmitted into the truck via ground-out through the engine
mounts.

Service Procedure
Initial Setup / Duplication / Evaluation:
Measure the vibration disturbance using the vibration analyzer, CH-51450-A (Pico Oscilloscope), to
qualify whether the issue frequency is E1.5 as opposed to E1 or E4.
Note: If using a single-axis pico sensor, mount and test both vertically and horizontally – E1.5
rough idle vibration will usually be horizontal / lateral at the seat track.

4532459

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(TA183 single axis pico sensor shown / TA143 is tri-axis sensor)
Add E1.5 to the displayed data and turn Off T and P related data (under Add Vibration in Pico)
since issue occurs with vehicle stationary.

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Note: Amplitude (mg) readings from a single-axis pico sensor will be approximately 10% lower than
with a
tri-axis sensor. For example, a reading of 4 mg using a tri-axis sensor, would likely measure as
about 3.6 mg on a single-axis sensor.
If the disturbance frequency measures at the seat track as E1.5 with amplitude of approximately 2
mg or higher using a tri-axis sensor, continue with steps in this bulletin to reduce the amplitude
(mg) of the disturbance, then exercise the vehicle and re-measure using Pico to determine level of
improvement.

If the E1.5 disturbance measures approximately 2 mg or lower using the Pico tri-axis sensor as
indicated – the vehicle is considered acceptable.
1. Place tri-axis pico sensor on the inboard seat track forward-most location to record
measurement of the rough idle vibration concern.
Note: Most rough idle in Drive concerns are temperature dependent and can be difficult to
re-create at times.
2. With A/C On, perform several short heavy launch events from stop to stop to bring the
temperatures back up while attempting to re-create the rough idle vibration in Drive with Pico
sensor placed on inboard seat track; while the vibration is active – Record Pico reading. This
method seems to provide better results than extended test drives.
3. If the Pico reading for E1.5, with vibration active, at the inboard forward seat track location
measures approximately 2 mg or higher – continue following steps in this bulletin to install
updated engine mounts and perform the engine/trans mount settling process.
4. If the Pico reading for E1.5, with vibration active, at specified seat track location measures
close to 2 mg or less – investigate other sources of the rough idle / vibration concern using SI
diagnostics.

Install Updated Engine Mounts and Engine/ Trans Mount Settling Process

For Vehicles Built Prior to:
SUV – February 2, 2017
V-6 PU – March 15, 2017
V-8 PU – March 22, 2017

Important: For any engine mount to frame bolts removed during this process. Replace the engine
mount to frame bolts with NEW bolts.
Important: Do Not use Impact wrenches when tightening the engine mount to frame bolts, or damage
to threads in the frame may result.
Important: Both LH and RH engine mounts need to be seated to the vehicle frame At The Same Time to
help ensure best alignment.

5030893
Note: Initial removal of the engine mounts will require the removal of the exhaust manifolds.
Summarized below are key notes for engine mount replacement for rough idle:
1. Replace both engine mounts (1). Refer to Engine Mount Replacement – Left and Right Engine Mount
Replacement in SI.
2. Install but do NOT tighten the mount to frame bolts.
3. Settle all mounts as follows:
3.1. Ensure the engine mount to frame bolts on both LH and RH sides are loosened a couple turns.
3.2. Ensure, the transmission/transfer case mount to frame crossmember nuts are loosened a couple
of turns.
3.3. Have assistant set park brake and apply base brake.
3.4. Have assistant turn Traction Control Off, and brake torque in Drive and Reverse with the
engine at operating temperature, then place in Neutral and turn engine Off.

3.5. In Neutral, with engine Off, using Only Hand

Shimming Procedure for Engine Mount

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Tools, torque all the new engine mount to frame bolts (1) in sequence shown;
3.5.1. 50 Nm (37 lb ft)
3.5.2. Final Pass 65 degrees
3.6. Torque the transmission/transfer case mount to crossmember nuts to 55 Nm (41 lb ft).
4. Re-evaluate the rough idle vibration – repeating steps 1-4 under Initial Set-up / Duplication /
Evaluation.
If the E1.5 idle vibration at inboard seat track forward location has been reduced to 2 mg or less
– the vehicle is considered acceptable.
If a different frequency other than E1.5 is now elevated, for example E4, then most likely one of
the mounts is bound. Carefully repeat the mount settling process for the engine and trans mounts,
then re-evaluate.

Vibration/Grounding after Mount Replacement

For Vehicles Built After to:
SUV – February 2, 2017
V-6 PU – March 15, 2017
V-8 PU – March 22, 2017

Important: For any engine mount to frame bolts removed during this process. Replace the engine
mount to frame bolts with NEW bolts.
Note: Idle vibration caused by ground-out within an engine mount may be able to be turned off/on
with a single bolt location. Shimming that bolt location may greatly reduce the vibration. In some
cases, a combination of bolt location shimming may be needed.
1. With the aid of an assistant, run vehicle in stall with the parking brake set and base brake
applied, in Drive, monitoring E1.5 on Pico at inboard seat track, with idle vibration active,
perform the following:

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Important: Do Not use Impact wrenches when tightening the engine mount to frame bolts, or damage
to threads in the frame may result.
2. Beginning with RH side, loosen the engine mount to frame bolts one at a time a few turns to
release clamp load beginning with rear bolt at position 6, front bolt at position 5 and the middle
bolt at position 4.
⇒ Verify if idle vibration was significantly reduced or eliminated when the bolts were loosened.
3. Torque bolts to specifications in order and validate if the vibration returns.
4. Repeat the process on the LH mount starting at the rear bolt at position 3, front bolt at
position 2 and the middle bolt at position 1.
• If idle vibration Does Not return when the RH or LH engine mount bolts are re-torqued to
specifications, remove the old bolts and discard. Replace the bolts with new ones.
• If idle vibration Does return, proceed with procedure.

Note: Pause after loosening any of the mount bolts during these steps to determine the effect of
the idle vibration on the Pico, at the seat track while making note of effect from each bolt
location.
5. Beginning with RH side, loosen the engine mount
(1) to frame bolts one at a time a few turns to release clamp load.
6. Remove the position 5 and 6 bolts (2),
7. Utilizing a jack with a block of wood, carefully raise the engine.
Note: For spacer washers mild steel is recommended, no stainless; it may be necessary for some
locations to use a small amount of adhesive such as ‘dum-dum’ to hold spacer in place.
8. If idle vibration was significantly reduced, add a spacer washer (3) approximately 2.5 mm thick
between the engine mount and frame at position 5 and 6.
9. Install old engine mount to frame bolts.
10. Lower the engine.
11. Torque the bolts to specifications to validate if the vibration returns:
• If idle vibration could be turned off with shimming one side, remove the old bolts and discard.
Replace the bolts with new ones.
• If idle vibration returns. Remove the shims and repeat the process for the LH mount.
12. Tighten the affected engine mount to frame bolts in sequence, to specification.

5164611
Re-evaluate the rough idle vibration by repeating steps 6-9 under Initial Setup / Duplication /
Evaluation.
⇒ If the E1.5 idle vibration at inboard seat track forward location has been reduced to less than
3 mg, determine with customer if condition is now
acceptable.
If there was not a single bolt location on the RH or LH mount which could turn the idle vibration
off/on, shimming will be necessary for 2 or 3 bolt locations on one side.
⇒ Go back to the 2 bolts with greatest effect recorded on vibration reduction on one side and shim
those bolts.

Fine Tuning – Pico Sensor on Mounts (If Needed)
Note: It is difficult to lower amplitude of E1.5 idle vibration at the seat track to about 2.5 mg
or lower. Many customers are satisfied with approximately 3 mg or less. Some customers may not be
satisfied until the idle vibration is brought below 3 mg, closer to 2.5 mg.
1. While the tri-axis sensor is mounted on the inboard seat track forward most location (Channels
A-C), Add a second Pico sensor tri-axis or single plane using Channel D.
2. Place the added Pico sensor on the middle engine mount bolt head, beginning with RH side.

3. For Pico readings from the mount, focus on Vertical E1.5. (suggest removing lateral and fore/

Parts Information

aft channels from display and removing E1 and E4 from display).
4. While the idle vibration is active, record the E1.5 amplitude (mg).
5. Repeat steps 1-4 for LH side while the idle vibration is active and compare readings.
6. Focusing on the side with highest E1.5 amplitude (mg), perform the following:
6.1. Place the added Pico sensor on the engine mount rear bolt head.
6.2. While the idle vibration is active, record the E1.5 amplitude (mg).
6.3. Move sensor to middle bolt head and repeat.
6.4. Move sensor to front bolt head and repeat.
⇒ if a spacer washer is not already in position, add a spacer washer approximately 2.5 mm

Causal Part
X
N/A N/A N/A N/A N/A

Description

Mount, Engine
BOLT, ENG MT FRM SI
GASKET, EXH MANIF
BOLT, EXH MANIF
SEAL, EXH SYS L
SEAL, EXH SYS R

Part Number

Refer to EPC

Qty

1 Set
3

1 per Side

5 per Side

1

1

thick between the engine mount and frame attachment at the bolt location with the highest recorded
E1.5 amplitude (mg).
7. Re-evaluate the rough idle vibration repeating steps 1-4 under Initial Setup / Duplication /
Evaluation:

Warranty Information
For vehicles repaired under the Powertrain coverage, use the following labor operation. Reference
the Applicable Warranties section of Investigate Vehicle History (IVH) for coverage information.

• If the E1.5 idle vibration at inboard seat track forward location has been reduced below 3 mg,
determine with customer if condition is now acceptable.
• If the E1.5 idle vibration at inboard seat track forward location has not been reduced below 3
mg, if a spacer washer is not already in position, add a spacer washer, approximately
2.5 mm think between the engine mount and frame attachment at the bolt location with the second
highest recorded E1.5 amplitude (mg). (Leave the spacer washer at the highest recorded bolt
location.)
8. Re-evaluate the rough idle vibration by repeating steps 1-4 under Initial Setup / Duplication /
Evaluation.

Labor Operation

4081688*

4086928*

Add

4081348*

Description

Perform Pico Scope Idle Vibration Measurement
Engine Mount Shimming Procedure – One Side
Note: Time Includes Engine and Trans Mount Settling.
Engine Mount Shimming Procedure – Both Sides

Engine Mount Replacement
– Both Sides

Labor Time

0.4 hr

1.5 hr

0.5 hr

3.8 hr (SUV)
3.1 hr (PU V-6)
3.2 hr (PU V-8)

*This is a unique Labor Operation for Bulletin use only.

Version

Modified

7
Revised June 6, 2017 – Updated information, moved Parts Information and Warranty Information tables
to bottom of bulletin and added Keywords.
Revised September 05, 2018 – Updated labor time information
Revised November 16, 2018 – Add Mount Shimming Procedure and Fine Tuning sections, Added 2018 Model
Year and Removed Vin Break Point.
Revised April 18, 2019 – Update Shimming Procedure section, Add build cutoff dates, Update Engine
Mount procedure, Updated Parts Information section and update the labor time.
Revised September 11, 2019 – Added to replace the engine mount bolts in both procedures.
Revised June 25, 2020 – Added note to remove exhaust manifolds and updated parts section.

Additional Keywords: PIP5211, PIP5211D, PIP5211E, vibration
GM bulletins are intended for use by professional technicians, NOT a “do-it-yourselfer”. They are
written to inform these technicians of conditions that may occur on some vehicles, or to
provide information that could assist in the proper service of a vehicle. Properly trained
technicians have the equipment, tools, safety instructions, and know-how to do a job properly and
safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or
that your vehicle will have that condition. See your GM dealer for information on
whether your vehicle may benefit from the information.
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