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2004 chevy trailblazer_lt_ext
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Discussion Starter #1
Okay, so I have a 2004 Trailblazer EXT with the 5.3 V8 (VIN code P) and I'm having an issue idling.... It's starts and runs fine for the most part... The problem comes in heavy traffic and at stop lights... My RPM's are dropping too low.... They go down to around 450-500 and it will stall if I don't toss it in neutral and manually raise the RPM's with the accelerator pedal. This problem does not show itself until the engine is warm (after about 15-20 min)... When I first start it up, it runs fine and RPM's are normal.

I've had it to the dealership now 3 times and they haven't been able to get the problem fixed.. I have new plugs, wires, MAP sensor, air filter, new battery, fresh synthetic oil and a new O2 Sensor.

I see alot of people having the same issue and they suggest cleaning the throttle body and another solution I found was to change the Cam actuator solenoid valve....

I have no idea where the CAM solenoid is and was wondering if someone could show me on a diagram... Also, I'm not even sure if I'm looking at the right part... I can't post a link cause my post count isn't high enough, but the part I'm looking at on Amazon is : cciyu VVT Exhaust Solenoids Camshaft Position Actuator fit for Buick Chevrolet GMC Hummer 2.8L 2.9L 3.5L 3.7L 4.2L 5.3L 6.0L :
 

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2004 chevy trailblazer_lt_ext
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7 Posts
Discussion Starter #2
anyone?

I sure could use some help.

When it comes to the variable valve timing solenoid, I'm a bit confused... I am finding some sellers that offer 2 of the VVT solenoids, one for the exhaust and one for the intake... Do I need to buy the set and where are they located?
 

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2004 gmc envoy_sle_xl
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9 Posts
I have the 4.2 engine, so I can't look to confirm the shop info.
You appear to have the single cam 5.3L LM4 engine, with cam, and crank, shaft sensors, but you don't appear the have a VVT actuator.
 

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2004 chevy trailblazer_lt_ext
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7 Posts
Discussion Starter #4
Hi Jal, thanks for the reply.... It appears I'm no further ahead than when I started....

I'm getting trouble codes P0171 and P0300 which both are pointing to lean conditions. The problem arises from all the different causes/fixes. The codes suggest it could be 1 or more of 20 different problems... Ugh...

I need help.... Any ideas?
 

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2004 gmc envoy_sle_xl
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9 Posts
Again, I don't have this engine, so I'm having to research like you need to do. It sounds like the dealer replaced almost everything it could be, except for the intake gasket.
I don't know how much experience you have under the hood, but there are a number of YouTube videos showing how to monitor the O2 sensors, and fuel trim levels, to see if you have a vacuum leak or other issue.
if you do have a vacuum leak, you may be able to use a spray bottle with water to locate the leak, although I would suggest caution, and limited amounts of water at a time, as you don't want to dump a lot of water in the engine if the leak is substantial. One potential vacuum leak this will not find is in the power brake vacuum line, which you should be able to check by pinching the line and seeing if the engine idle improves..
 

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p0171

If you have lean code(s) the first thing I would look at is the air flow meter. If you can access freeze frame data, find what driving condition set this code, see if long term fuel trims are high on both banks. I run a shop and the most common cause of lean mixture is the MAF being dirty. Look with a magnifier through the screen at the tiny sensing elements. Clean them very carefully as they are delicate.
 
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