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2006 Chevy Trailblazer_LT, 4.2L L6 Engine
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Discussion Starter #1 (Edited)
I have a 2006 Trailblazer LT 118000 miles. 4.2 L6 Engine
I have been fighting with this issue for over a year.
I have checked oil level
Changed oil and filter
Replaced the Cam Sensor
Replaced the VTT (2X)
Replaced All 6 Ignition Coils
Replaced all plugs
I have cleared codes what seems like 100’s of times.
I talked to a mechanic and he said that I have done everything that he would have done.
I am still getting the same P0016 code.
How do I get rid of it?
 

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2004 chevy trailblazer_lt
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872 Posts
Just a couple of questions from me. What brand or brands of VVT solenoids did you use? What brand of camshaft position sensor did you use?

How does the electrical connector that plugs into the VVT solenoid look? Does it feel gooey as if it is decomposing? Where the wires go into the plug, are they secure, are there any gaps between the wire insulation and the plug body?

How often are you changing your oil and oil filter and what weight of oil are you using?
 

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2008 chevy trailblazer_lt
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32 Posts
Could be electrical or mechanical. A knowledgeable mechanic with a good bidirectional scan tool should be able to diagnose. How does vehicle run? Low oil pressure? Timing chain slack? Vvt tests can be done with a scan tool by commanding vvt solenoid and looking at desired and actual. Pcm monitors cam position sensor to verify vvt solenoid operation. Vvt is power side switched pwm by pcm. Verify with labscope. Hard to say without testing where your problem is. Need to find a mechanic that knows what they are doing. Knowledge and proper testing equipment. I would pay an hour of diagnostic time to a ase certified shop that specializes in electrical /diagnostics driveability. When you replaced vvt solenoid screens looked clean. I use scan tool tests and then sometimes scope pcm signal from pcm. Oil pressure gauge read OK. Any engine noise.
 

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2008 chevy trailblazer_lt
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32 Posts
IAGNOSTIC AIDS

  • The scan tool cam phase control function increments the cam phaser in 10 percent increments. Each increment equates to 2.5 degrees of cam phasing. A cam phase angle of 15 degrees is achieved by commanding the phaser with the scan tool to 60 percent .
  • Inspect any engine mechanical work that has been performed recently. Verify that the engine timing has not been altered.
  • If this DTC is set along with any crankshaft position (CKP) or camshaft position (CMP) sensor DTCs, then both the CKP and CMP sensor DTCs should be diagnosed prior to performing this diagnostic. The PCM uses both inputs to determine the actual camshaft position.
  • Check the following items:
  • A loose CMP sensor causing a variance in the sensor signal
  • A loose CKP sensor causing a variance in the sensor signal
  • Excessive free play in the timing chain and gear assembly
  • Debris or contamination interfering with the camshaft position actuator solenoid valve assembly
  • Debris or contamination interfering with the camshaft position actuator assembly
  • Engine oil has a major impact upon the camshaft actuation systems responsiveness. Oil temperature, viscosity, and quality can slow and/or inhibit the phaser's ability to reach a desired phase angle.
 

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2008 chevy trailblazer_lt
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On scan tool can command vvt solenoid on with engine running.....look at actual and desired as you increase percentage and also a data pid variance difference between actual and desired. If that doesn't move electrical checks would have to be done at vvt solenoid. If pcm control and ground circuit are good then have to look at cam position sensor in response to vvt solenoid movement. Small oil passages can get clogged. Oil quality and pressure important. Hard to test without proper testing equipment. Oil pressure good.... Any engine noise... What if any driveability problems are you having.
 

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2002 chevy trailblazer_lt
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900 Posts
For what it's worth,,, all these cam data points CAN be monitored with an investment of less than $20 on a good bluetooth OBD2 adapter and a smartphone app.

Here is a screenshot of my 2002 Trailblazer LL8 seen in Torque Pro. The data points (pids) need to be added as they do not come with the app.

20190822_211305 (5).png
 

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2008 chevy trailblazer_lt
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32 Posts
Monitored but no bidirectional control. Control while monitoring actual. Also can control solenoid on and off koeo with scope hooked up to test controls. I bet your tool can't do that.
 

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2008 chevy trailblazer_lt
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32 Posts
What happens when your cheap scan tool shows no vvt movement from processed data? And no bidirectional control capability?
 

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2002 chevy trailblazer_lt
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900 Posts
What happens when your cheap scan tool shows no vvt movement from processed data? And no bidirectional control capability?

Many people believe there is some magic in these high dollar scan tools, and there is! But it is in the knowledge written into the software, NOT in any special expensive hardware. EVERYTHING done by these expensive tools is sent in the very same SAE J1850 VPW message structure. Learn the language and you then have the knowledge yourself and can send the commands, instructions and whatever the high priced licensed softwares do for those who do not know the language.
 

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2008 chevy trailblazer_lt
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If you know electronics you can manually energize whether power or ground side switch but pwm is more difficult. Need knowledge of circuit design and good bidirectional scan tool makes it easier and a labscope is a must now days. Been doing diagnostics for 35 years studied electronics. Everything on a vehicle is electronics. A good scan tool is a must. Then there is j2534 programming.
 

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2002 chevy trailblazer_lt
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900 Posts
pwm is more difficult.
Agreed, what I post is simply intended to give users an inexpensive way to obtain some data they would otherwise not have access to. The proliferation of inexpensive adapters and smartphone apps makes it simple (somewhat) to even record driving session data for capture of intermittent faults.

So now, PWM is handled in SAE J1850 VPW messaging as a single byte hexadecimal value in the range of 00 to FF where 00 is 0 percent and FF is 100 percent. When you press the button on your Tech 2 scantool or equivalent it sends a message requesting device control for the selected output with the desired value encoded therein. As a quick example I have a button configured to send a command instructing my cooling fan clutch to engage at 37.5%. looks like this...

Screenshot_20210214-102932.png



The first string sets my message type as a node to node message from the default scantool address of F1 to node address 10 (PCM). The second string is a device control request with the various parameters required to set the PWM at 0x60 which is 37.5 percent.
 

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2002 chevy trailblazer_lt
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900 Posts
Now for some on topic information regarding the P0014 you are experiencing. I mentioned an OBD2 adapter. I use a half dozen different apps for differing purposes. One app, Car Scanner, can record data points for later analysis. As an example here is a clip where I display some cam phaser operation.

Screenshot_20210214-105951.png



Now you can call up freeze frame data with many common scanner/code readers and that gives a momentary snapshot of conditions when the code set, this gives you a wider look at how the phaser is operating in real driving conditions. So if for example the phaser was sticking that would be readily apparent here.
 
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