Car shuts off while driving

Tiny
CANNON1349
  • MEMBER
  • 2005 GMC ENVOY
  • 4.2L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 203,000 MILES
This car has been a great vehicle, virtually no problems outside oil changes and brake changes, and tune ups. Lately while driving the engine will "cut off" and sometimes I can catch it and stomp the gas pedal and it'll revive itself. At idle, it will just shut off, randomly. Oil level is good, no engine light.

I have a hunch it has something to do with the throttle position sensor.

Any ideas?
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Tuesday, July 2nd, 2019 AT 5:45 AM

5 Replies

Tiny
JACOBANDNICKOLAS
  • EXPERT
Welcome to 2CarPros.

When this happens, do you ever have to wait for the engine to cool a bit before it will restart? If so, my first suspect is the crankshaft position sensor. When they start going bad, they are affected by heat, which causes them to fail until they have a chance to cool a bit. Interestingly, often times, they will not set a code which in turn, doesn't set the check engine light to come on. On the other hand, a throttle position sensor usually will set the check engine light to come on.

Take a look through these links and let me know if anything mirrors what you experience. The second link will discuss symptoms.

https://www.2carpros.com/articles/how-a-crank-shaft-angle-sensor-works

https://www.2carpros.com/articles/symptoms-of-a-bad-crankshaft-sensor

https://www.2carpros.com/articles/crankshaft-angle-sensor-replacement

_______________________________

If you find the sensor is the issue, here are the directions specific to your vehicle for replacement. The attached pictures correlate with the directions.

CRANKSHAFT POSITION (CKP) SENSOR REPLACEMENT
CRANKSHAFT POSITION (CKP) SENSOR REPLACEMENT

REMOVAL PROCEDURE
1. Raise and support the vehicle. Refer to Vehicle Lifting.

pic 1

2. Disconnect the crankshaft position (CKP) sensor harness connector.
3. Remove the CKP sensor retaining bolt.
4. Remove the CKP sensor from the engine block.

INSTALLATION PROCEDURE

IMPORTANT: Inspect the sensor O-ring for the following conditions:
- Any wear
- Any cracks
- Any leakage

Replace the O-ring if necessary. Lubricate the new 0-ring with engine oil before installation.

pic 1

1. Install the CKP sensor into the engine block.

NOTE: Refer to Fastener Notice in Service Precautions.

Tighten the bolt to 10 N.m (89 lb in).

2. Install the CKP sensor retaining bolt.
3. Connect the CKP sensor harness connector.
4. Lower the vehicle.
5. Perform the CKP System Variation Learn Procedure. See: Vehicle > Programming and Relearning

________________________________________

Here are the relearn procedures. However, it will require a scanner to complete.

CKP SYSTEM VARIATION LEARN PROCEDURE

1. Install a scan tool.
2. Monitor the powertrain control module (PCM) for DTCs with a scan tool. If other DTCs are set, except DTC P0315, refer to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information.
3. Select the crankshaft position variation learn procedure with a scan tool.
4. The scan tool instructs you to perform the following:
1. Accelerate to wide open throttle (WOT).
2. Release throttle when fuel cut-off occurs.
3. Observe fuel cut-off for applicable engine.
4. Engine should not accelerate beyond calibrated RPM value.
5. Release throttle immediately if value is exceeded.
6. Block drive wheels.
7. Set parking brake.
8. DO NOT apply brake pedal.
9. Cycle ignition from OFF to ON.
10.Apply and hold brake pedal.
11.Start and idle engine.
12.Turn the A/C OFF.
13.Vehicle must remain in Park or Neutral.
14.The scan tool monitors certain component signals to determine if all the conditions are met to continue with the procedure. The scan tool only displays the condition that inhibits the procedure. The scan tool monitors the following components:
- Crankshaft position (CKP) sensor activity-If a CKP sensor condition occurs, refer to the applicable DTC.
- Camshaft position (CMP) signal activity-If a CMP signal condition occurs, refer to the applicable DTC.
- Engine coolant temperature (ECT)-If the engine coolant temperature is not warm enough, idle the engine until the engine coolant temperature reaches the correct temperature.
5. Enable the CKP system variation learn procedure with the scan tool and perform the following:
- Accelerate to WOT

IMPORTANT: While the learn procedure is in progress, release the throttle immediately when the engine starts to decelerate. The engine control is returned to the operator and the engine responds to throttle position after the learn procedure is complete.

- Release the throttle when fuel cut-off occurs
- Test in progress

6. The scan tool displays Learn Status: Learned this ignition. If the scan tool indicates that DTC P0315 ran and passed, the CKP variation learn procedure is complete. If the scan tool indicates DTC P0315 failed or did not run, refer to DTC P0315. If any other DTCs set, refer to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information.
7. Turn OFF the ignition for 30 seconds after the learn procedure is completed successfully.

The CKP system variation learn procedure is also required when the following service procedures have been performed, regardless of whether or not DTC P0315 is set:
- An engine replacement
- A PCM replacement
- A crankshaft balancer replacement
- A crankshaft replacement
- A CKP sensor replacement
- Any engine repairs which disturb the crankshaft to CKP sensor relationship

__________________________________

Let me know if this helps or if you have other questions.

Take care,
Joe
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Tuesday, July 2nd, 2019 AT 8:48 PM
Tiny
CANNON1349
  • MEMBER
It sounds like it regarding stalling at idle, but also I felt it while driving. And usually it starts right back up. Sometimes, the car will lock the key in the ignition and i'll have to jiggle the steering wheel to let me start it again
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Wednesday, July 3rd, 2019 AT 4:10 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Welcome back:

Chances are it is related to the sensor. The only way to be sure is by using what is called a live data scanner. With that, you can see if spark is lost as a result of a bad sensor or what is called freeze frame data can be reviewed to see what happened.

I have a feeling that is the issue, but can't be 100% sure without testing with the scanner.

Let me know if you have other questions.

Joe
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Wednesday, July 3rd, 2019 AT 5:31 PM
Tiny
CANNON1349
  • MEMBER
Well I do have a scanner but not one to do a relearn procedure for the sensor. Is there one I can buy?
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Sunday, August 4th, 2019 AT 6:50 AM
Tiny
KEN
  • ADMIN
If I can jump in here. it sounds like the car is going into limp mode due to a dirty throttle body. here is a guide that will help fix it I hope:

https://www.2carpros.com/articles/throttle-actuator-service

Please run down this guide and report back.

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Tuesday, August 6th, 2019 AT 12:02 PM

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