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Discussion Starter · #1 ·
My TB will start but run badly and when I unplug the IAT it revs up higher. P0016 and P0171 keeps popping up. I already replaced the Cam actuator. Any thing else I could be checking?
 

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2004 chevy trailblazer_lt
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Welcome to the Forum.

Were the codes present before you changed the cam actuator?
 

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2004 chevy trailblazer_lt
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OK. What diagnostics did you do?
 

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Discussion Starter · #5 ·
I have a code reader I got from O'Reilly and I hooked it up through the Bluetooth on my phone and the actuator was recommended to be the culprit. The head was replaced last year due to a shop dropping a bolt into the intake and it got stuck in a valve. It ran great for 5 months until this happened.
 

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2004 chevy trailblazer_lt
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OK, thanks. Sorry for my delayed response - had a phone call.

First off the P0016 code is telling you that there is a problem with the correlation between the Crankshaft Position Sensor and the camshaft position sensor data streams. Causes - wiring issue (broken wire, loose wire, poor electrical connection, etc.), a bad sensor (either camshaft position or crankshaft position), or the timing chain jumping a tooth or stretched too much. It does not tell you that this part or that part is bad or needs to be replaced. It tells you there is a problem and where to look to find the cause of the problem.

Here is a link to a webpage about P0016:


Second, the P0171 code is telling you that the engine is running lean. Causes - there could be a vacuum leak, one of the oxygen sensors could be wonky (most likely the upstream O2 sensor), there could be a fuel injector not working due to an electrical problem or it could just be clogged, or there could be low fuel pressure. Here is another link for more detail:


So, what does this all mean? Well, it means you need to determine if you have a vacuum leak, a bad O2 sensor, a wiring problem to the O2 sensor, what the fuel pressure is to make sure the fuel pump is operating properly, etc. AND, you need to see if the camshaft position sensor is functioning properly and if the crankshaft position sensor is as well. Be careful not to disturb the crankshaft position sensor or else you will need to have a complex procedure performed to "sync" the crankshaft and the camshaft sensors which involves data being written to the Engine Control Module. Most of the time this code is related to the camshaft position sensor.

Does your Bluetooth code reader also display live data - say for example Long Term Fuel Trim values or Oxygen Sensor voltage? Are you able to save this live data with your Bluetooth Dongle? What app are you using in conjunction to the Bluetooth OBDII dongle?
 

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2004 chevy trailblazer_lt
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Oh yes, I forgot to add this, the link below will show you how to test the camshaft and crankshaft position sensors.


Good Luck!
 

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2004 chevy trailblazer_lt
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OK, I see exactly what you have. If you are going to start doing your own maintenance, may I suggest the following - provided you have an Android device - a Bluetooth OBDII dongle and the Torque Pro app from the google play store. Total price is under $25.00, and it will run circles around the Innova 5310 because it allows you to view multiple sensors, etc. simultaneously and it will save the raw data in an Excel like spreadsheet for additional analysis away from the vehicle.


I have two of these setups and I also used to own an Innova 3160B code reader live data scanner. It would let me capture about 100 frames of data. The Torque Pro app with the Bluetooth OBDII dongle lets me store hours of data for multiple sensors automatically, and then I can transfer that data file to my laptop or desktop computer for further analysis. I have to admit the Bluetooth Dongle and Torque Pro app, puts the Innova 3160B to shame.
 

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Discussion Starter · #10 ·
I am back with an update! I ended up having to replace the fuel pump. I tested the fuel pressure and it was only pushing 20 psi. Now I can drive it but the CEL comes on intermittently and I'm still getting the P0016. The issue now is that it will rev up to 4000 rpm and very slowly come down. If I turn on the AC it won't Rev up but it does rev up each time the AC cycles. Live data shows that the tps is at 38% when it's reving. I'm thinking about replacing the vvt actuator solenoid and cleaning the throttle body. Does this sound like it could help my issues? Thank you
 

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2004 chevy trailblazer_lt
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Before you clean the throttle body, clean the PCV system first. Here is how to do it:


Now if you still want to clean the throttle body, here is how to do it:


Now, heed this:

DO NOT DISCONNECT THE BATTERY - REMOVE THE APPROPRIATE FUSE(S). Why? Because when you reconnect the battery, the HVAC actuators inside of the dash are commanded to run a recalibration procedure which stresses the old brittle plastic gears inside the actuators and the brittle plastic gears break and leaves you unable to control where the air comes out, or control the temperature of the air, etc. Replacing at least one of them literally requires the removal of the entire dash! So, if you ever need to actually disconnect the battery, such as in the case of needing to install a new battery, be sure and use some kind of Keep Memory Alive device to avoid the HVAC actuator recalibration routine.

Did you ever test the camshaft and crankshaft position sensors? I would do that before changing the VVT. Also, be sure and make sure the wires going to the connectors are intact. Now, do not change the Crankshaft Position Sensor "just in case" because if you change it, it requires a dealer level bi-directional scan tool (like a Tech 2) in order to perform as crankshaft angle relearn procedure in order for the engine to run properly!

Good Luck!
 
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