Stalling & Hesitation Advice - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum



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Go Back   Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum > 2002 - 2009 TrailBlazer/Envoy Tech > 02-09 Vortec 4.2L I-6 Engine and Drivetrain > OEM Issues

OEM Issues Original Equipment Repairs and/or Problems

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  #1  
Old 07-01-2019, 10:08 AM
Christopher MC Christopher MC is offline
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Question Stalling & Hesitation Advice

Hello everyone my name is Chris and I am new around here. I am glad I found this place because I can really use some help from people who know what they are talking about. I've taken to trying to repair an issue myself rather than the usual trip to the mechanic because they have failed to solve or find the issue. I have a stalling and hesitation issue and I will put the details in bullets below because I know that makes it easier for everyone to read rather than pulling details out of an essay.

2002 Trailblazer LTZ 4.2 6 cyl

Conditions for stalling/hesitation
1. Must have sat for more than 12 hours
2. Must be cold
3. Once fully warm runs like a dream
4. Runs great from the get go if cold but has sat for 11 hours or less
5. No codes or lights


What I have done so far
1. Fully removed and cleaned throttle body spotless
2. Replace all 6 coil packs and plugs
3. Replaced cam position sensor
4. Ran 1 1/2 tanks of fuel system cleaner with 93 fuel

So my next thought is water in the tank? It has never sat long enough for that to be a likely issue.

So next I want to change the Camshaft Position Actuator Solenoid. This is where I am looking for advice. This job is outside my skill level and will have to pay a mechanic. So before I go and tell him to change it, is this a possible cause of my issue??

Thanks all!
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  #2  
Old 07-01-2019, 11:28 AM
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EnvoyBoy2004 EnvoyBoy2004 is offline
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2004 GMC Envoy SLT
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Do not change parts just by guessing. I think the only way to diagnose this issue is to monitor the live data on the OBDII port with a scan tool when the engine is cold. I believe that the intake air temperature sensor may be giving incorrect data to the PCM. Another possibility is a malfunctioning MAF sensor. These can be confirmed by a technician using a scan tool.
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Old 07-01-2019, 01:31 PM
Christopher MC Christopher MC is offline
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Good advice I just don't have that kind of equipment and the mechanics I have tried are not finding it.
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Old 07-01-2019, 02:15 PM
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EnvoyBoy2004 EnvoyBoy2004 is offline
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Maybe you need to find an ASE certified mechanic. Today's vehicles are complicated.
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Old 07-02-2019, 10:48 AM
Christopher MC Christopher MC is offline
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That is what I am going to do thanks
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Old 07-03-2019, 06:47 PM
tak1313 tak1313 is offline
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The fact that it's something happening at cold start means it's an open loop issue - ie. the O2s haven't warmed enough, so it's relying on "default" parameters based on the MAP/MAF. My 2007 uses a MAF, but I THINK back then they used a MAP/IAT?

That may point you in the right direction.
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Old 07-03-2019, 07:26 PM
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tblazed tblazed is offline
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Is this a recent issue? There was a stalling update I had done to mine years ago when it was still under warranty. Hasn't stalled or died sitting at a red light since.

I doubt the cam position solenoid is the problem, plus if you've done 1 thru 3 replacing it would be a piece of cake. I replaced mine because it was leaking oil.
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Old 07-03-2019, 07:33 PM
samlab1 samlab1 is offline
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What state are you in....if your close drive over....if you cleaned the throttle body then replacing the cam sensor and vvt sensor is easy both are 10mm screws, pull the belt release the three 13mm from behind the power steering sprocket the one down below you can loosen enough sometimes to get out of the way to remove the vvt....use only ACDelco parts!!

Typically when the VVT is old and the micro screen clogged you get funckanosis big time especially upon start up after sitting and cold. Once installed pull fuse 10 and 28....the chart is on the underside of the plastic fuse box cover....say 30 min or longer....reset the fuses go have fun....the relearn for the throttle body is 3min turn on and run at idle....turn off for 60 seconds....them turn on and run for 3 mins....then shut car down....next drive make it round trip 40 miles come back home get up next am and you should be good to go....have him look at your bearings and pulley on front they are easy and inexpensive to replace too.
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Old 07-10-2019, 07:47 PM
Christopher MC Christopher MC is offline
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Quote:
Originally Posted by tak1313 View Post
The fact that it's something happening at cold start means it's an open loop issue - ie. the O2s haven't warmed enough, so it's relying on "default" parameters based on the MAP/MAF. My 2007 uses a MAF, but I THINK back then they used a MAP/IAT?

That may point you in the right direction.
Thanks!! Here is something else its not just a cold start but it has to be a cold start after an extended sit. It can be ice cold but if I drove it to work it will start up and drive fine on my way home. Next morning, its up to its shenanigans again...
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Old 07-10-2019, 07:48 PM
Christopher MC Christopher MC is offline
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Quote:
Originally Posted by tblazed View Post
Is this a recent issue? There was a stalling update I had done to mine years ago when it was still under warranty. Hasn't stalled or died sitting at a red light since.

I doubt the cam position solenoid is the problem, plus if you've done 1 thru 3 replacing it would be a piece of cake. I replaced mine because it was leaking oil.
Yes only started a few months ago. The second part requires removing the belt and moving the water pump out of the way. I could do it but you might say I mechanically inclined but not inclined to be a mechanic
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