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2004 gmc envoy_slt_xuv
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Discussion Starter #1
2004 GMC Envoy SLT XUV 4.2L 156,000 miles- the car that made GMC bankrupt.
So I had a problem with cruise control not working, and then I got a p0340 error code plus a code my OBD couldn't read).
Before we go any further: I'm a weekend warrior, with no real mechanical knowledge or skills, you guys and your damned how-tos are enablers.
I found on here I should start by cleaning the throttle body because sometimes it gets sticky. Pulled it off, and it looks fine with only minor deposits which I clean off. While putting it back together I missed connecting this loose hose which sticks out the bottom of what I'll call the air box (it has the VTEC logo on it, big plastic box on top of the coils).
Excited for my car to work, I go to pick up the kids ~3 miles away. Disaster. Engine now feels clunky, my passenger-side temperature actuator is misaligned and my 6 cd changer has taken a s**t (that's for another thread). To boot, I'm throwing codes p0340.
Time to clean the camshaft position sensor and the camshaft position actuator- with another fine how to on this forum! They look pretty clean, but I have some ether left so I try to spray them out anyways.
Happy I'm able to get the serpentine belt back on, I start up my truck to find new codes p0305 AND p0340.
Poop. Throw parts at it. Yesterday I got my set of Coils in the mail along with 5 of the 6 spark plugs I ordered (AMAZON!?!?!).
Changed them all out, and still no avail. Every time I go a few miles it throws p0340 with either a single coil fault (p0301, p0304, p0305) or random misfire, p0300.
Probably just going to try to find a new mechanic (my last 2 just cashed in a sold to folks from out of town).
Think I need to buy a new camshaft position sensor and camshaft position actuator? Intake manifold gasket?

Cheers in advance.
 

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2003 chevy trailblazer_lt_ext
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331 Posts
I think you are on the right track...but if I were you I would try changing or chasing just one code at a time. Too many changes (fixes) at a time without results is making the diagnostics too difficult to pin down.

I would deal with P0340 first. The sensor and actuator are not really expensive parts so I would just go ahead and change them both out. Check for codes when completed.

Common problems that come up after repairs done:
-hopefully you disconnected the battery (or pulled fuse) when you cleaned the TB. The throttle position actuator seems to be prone to issues if moved around without disconnecting the battery

-coils. its very easy to misalign the "boot" when inserting the coil pack. Results in misfire on that cylinder.

Good luck to you. I'm sure it will get sorted out if you just go one step at a time
 

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2008 gmc envoy_sle
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579 Posts
congrats on doing it yourself.

we will get you through this.

we do not recommend disconnecting the battery to clear the pcm for a throttle body cleaning. we would suggest to pull fuses 10 and 28 (PCM A and B) instead. that would have saved your temp actuator (blend door for HVAC)

p0340: check the camshaft position sensor wiring, and if needed replace it.
 

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2004 gmc envoy_slt_xuv
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Discussion Starter #4
Thanks folks,
I wrote an update last week, but it was never cleared by a moderator!

Here's the scoop:

Switched out all coils and spark plugs, didn't help. Brought in to a random mechanic since mine all moved away- bad idea. They told me I had a bad coil and that there was 1 sensor broken (but didn't have time to ID which one, it would take another hour and $165 to solve).
Some miscommunication between the Tech and the Owner led me pay the $165 'diagnostic' charge and get the heck out of there. I went right to autozone and picked up a new camshaft position sensor (not the actuator solenoid) and swapped it out- worked like a charm!

To the shop owner's credit he later called me to fess up and say 'You have a V6, the tech told me it was a V8, which is why my charges on repairs were gonna be so high and take so long".

Now the doozy- for the passenger side temperature actuator- I couldn't get to the last screw to switch it out, but I could unplug it and get to the pins. I rigged up a 12v battery and matched it to some pins on the actuator while it was still in place (find the video by searching for HVAC Temperature Actuator Reset ACDelco TechConnect on youtube).
I tried forward, and the reverse, and saw the guide moving on reverse. I held the contacts until it came to a stop and now I have cool air blowing out of my Passenger and Read vents!
Not sure if this reset the actuator, or if I will have to switch it back when the weather dies down, but for now I'm feeling pretty good.

Thanks for the help.

Would be interested in more info on when to use a battery tender to hold charge on vehicle when I'm doing these sorts of repairs... seems like disconnect battery vs. pull fuses is a hot topic!
 
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