2009 Denali 6.2 misfire detonation

[Dave Wilson]

New member first post,hopefully I can be steered in the right direction. 4 weeks ago my wife’s truck started missing and detonating pretty severely. It took a while to kick codes but eventually p341 and p340 came up. I replaced the cmp sensor with a borg Warner brand and the truck was fine for 2 weeks. The exact symptoms reappeared and my parts store exchanged it out with an ac delco and I also replaced the harness this time. Fast forward 2 weeks later and the exact symptoms reappeared again with a p341 code. I checked for frayed wires, sprayed electrical cleaner on the connections and cleared the code. Will drive it tomorrow and see how I make out. I have an older Solus Pro scanner but it is updated till 2012. Any help would be greatly appreciated. I am at wits end. Thanks Dave

 

[swathdiver]

Scan Tool Reference
Control Module References for scan tool information
CIRCUIT/SYSTEM VERIFICATION

1. Ignition OFF, inspect the engine wiring harness carrying the CMP sensor circuits for the
following conditions:
● Close routing of aftermarket electrical equipment
● Close to solenoids, motors, and relays
○ Correct any wire harness routing or component placement conditions, if it is determined to be a
possible source of electrical interference.
2. Start the engine. Using the live plot function on the scan tool, select the CMP sensor
parameter. Change the minimum spec to 400 RPM, and the maximum spec to 4,000 RPM. Select the CKP
sensor parameter. Change the minimum spec to 600 RPM, and the maximum spec to 3,300 RPM.
3. Observe the scan tool.
4. Quickly accelerate and release the accelerator pedal several times. Do not accelerate pass 3,200
RPM. The graphed lines on the live plot display should track together across the screen.
5. Operate the Vehicle within the Conditions for running the DTC. You may also operate the vehicle
within the conditions that are captured in the Freeze Frame/Failure Records data list.

CIRCUIT/SYSTEM TESTING
1. Ignition OFF, inspect the CMP sensor for correct installation.
○ If the CMP sensor is loose, inspect the sensor and the O-ring for damage, replace as necessary.
2. Inspect the engine for the following conditions:
● Engine oil for debris
● Camshaft reluctor wheel for damage
● The timing chain, timing chain tensioner, and sprockets for wear or damage
○ Repair or replace any worn or damaged components. Refer to Camshaft Timing Chain and Sprocket
Cleaning and Inspection .

COMPONENT TESTING
1. Inspect the CMP sensor for correct installation. Remove the CMP sensor from the engine and
inspect the sensor O-ring for damage.
○ If the sensor is loose, incorrectly installed, or damaged, replace the CMP sensor.
2. Connect the CMP sensor harness connector to the CMP sensor.
3. Ignition ON, engine OFF. Observe the CMP Active counter parameter on the scan tool.
4. Pass a flat steel object across the tip of the sensor repeatedly. The CMP Active counter
parameter should increment with each pass of the steel object.
○ If the parameter does not increment, replace the CMP sensor.

 

[Dave Wilson]

Scan Tool Reference
Control Module References for scan tool information
CIRCUIT/SYSTEM VERIFICATION

1. Ignition OFF, inspect the engine wiring harness carrying the CMP sensor circuits for the
following conditions:
● Close routing of aftermarket electrical equipment
● Close to solenoids, motors, and relays
○ Correct any wire harness routing or component placement conditions, if it is determined to be a
possible source of electrical interference.
2. Start the engine. Using the live plot function on the scan tool, select the CMP sensor
parameter. Change the minimum spec to 400 RPM, and the maximum spec to 4,000 RPM. Select the CKP
sensor parameter. Change the minimum spec to 600 RPM, and the maximum spec to 3,300 RPM.
3. Observe the scan tool.
4. Quickly accelerate and release the accelerator pedal several times. Do not accelerate pass 3,200
RPM. The graphed lines on the live plot display should track together across the screen.
5. Operate the Vehicle within the Conditions for running the DTC. You may also operate the vehicle
within the conditions that are captured in the Freeze Frame/Failure Records data list.

CIRCUIT/SYSTEM TESTING
1. Ignition OFF, inspect the CMP sensor for correct installation.
○ If the CMP sensor is loose, inspect the sensor and the O-ring for damage, replace as necessary.
2. Inspect the engine for the following conditions:
● Engine oil for debris
● Camshaft reluctor wheel for damage
● The timing chain, timing chain tensioner, and sprockets for wear or damage
○ Repair or replace any worn or damaged components. Refer to Camshaft Timing Chain and Sprocket
Cleaning and Inspection .

COMPONENT TESTING
1. Inspect the CMP sensor for correct installation. Remove the CMP sensor from the engine and
inspect the sensor O-ring for damage.
○ If the sensor is loose, incorrectly installed, or damaged, replace the CMP sensor.
2. Connect the CMP sensor harness connector to the CMP sensor.
3. Ignition ON, engine OFF. Observe the CMP Active counter parameter on the scan tool.
4. Pass a flat steel object across the tip of the sensor repeatedly. The CMP Active counter
parameter should increment with each pass of the steel object.
○ If the parameter does not increment, replace the CMP sensor.

 

[Dave Wilson]

Thanks for that very informative reply. My Snap On guy suggested many of the same things to look at. I inspected most of the wiring associated with the cmp sensor. There is a slight oil leak near the area (looks like coming from cooler lines) which is seeping on the wiring area. One thing that surprised me was an area of wire loom which dried out and was missing in the general area. Will drive it today and see how I make out. Thanks Dave

 

[swathdiver]

Anytime Dave. A good scan tool is essential for working on these.