NEED HELP Envoy turns off sometimes when stopped

suncountry72

Original poster
Member
Jun 27, 2016
4
Puerto Rico
Hi. I have an Envoy 4.2 2005. And it is turning off at idle while waiting at a traffic light or a traffic jam with no apparent reason. Don't give any code and check engine light is off. After turning it on again it can run again fine. There after 3 or more weeks then the problem came again. I turn it on and then runs fine and after three days then the problem came back.. It is not constantly. My ThrottleBody is clean. Its giving me a headache there is no code at the pcm..Thanks
 

AzTruckGuy

Member
Dec 1, 2015
501
scottsdale, az
Sounds like my 2003 Trailblazer it would stall and shut off at idle and when I would give it gas sometimes. There are others who also experienced this and I think its not just coincidence that it does this. Unlike you I had a P0440 code which seemed to have to do with evp purge valve, I also had a bad leak in my fuel tank. I give the Trailblazer a tune up changed plugs, fuel filter, air filter, cleaned the Throttlebody, new battery, new ignition switch, soldered up some lose wires since someone hacked into the stereo.

It cleared up a little but still experienced it from time to time, got the fuel tank fixed under warranty by Chevy and bought the purge valve on the drivers side of the engine block and installed it. So far so good it seems to be running smooth, but the PCM is also relearning, so I am going to have to wait to see if it clears this stalling issue I have.

The thing with the issue is, you can throw money at parts that are maybe be failing or not. One of the things that requires others input to pin point what is really causing the issue.
 

kickass audio

Member
Aug 25, 2012
955
Mine does the same thing and it's annoying as all hell. Totally random too. Whether it's cold, hot, air conditioning on or off doesn't matter. My throttle body is clean, no codes at all. Mine will even do it sometimes when I am driving around where it's like I shut the key off for a split second and then back on. If you look at it carefully when it happens, the check engine light will flash for a split second, the idle (if sitting at idle) will drop to around 250rpm and the truck will sputter like a horrible misfire. When I am driving and it happens it will drop the rpm a little but act almost like a clogged catalytic converter with being slow at responding to throttle and maybe drop my speed a tad bit if I hold the throttle steady. It will also flash the check engine light for a split second. I wouldn't worry about it. It is a pain in the ass but isn't anything bad from it. If you are driving around it won't stall out but if you're at idle and it happens it maybe like 3/4 of the time will stall out but will restart perfectly fine.

Just as a tip, if you stall at a stop while in gear just shift to neutral and start the engine then go back into drive. No need to go into park and then start it up again.
 

AzTruckGuy

Member
Dec 1, 2015
501
scottsdale, az
When I am driving and it happens it will drop the rpm a little but act almost like a clogged catalytic converter with being slow at responding to throttle and maybe drop my speed a tad bit if I hold the throttle steady. It will also flash the check engine light for a split second. I wouldn't worry about it. It is a pain in the ass but isn't anything bad from it. If you are driving around it won't stall out but if you're at idle and it happens it maybe like 3/4 of the time will stall out but will restart perfectly fine

I don't know about you but if I was driving and it stalled I would be worried about that, that's an accident waiting to happen. I have a feeling that this is known issue with Chevy and they have failed to fix it. I have researched this and theres a lot of people that experience this issue.
 

kickass audio

Member
Aug 25, 2012
955
Honestly the vehicle is still with the key in the on position so the airbags would go off in a collision as well as since it's rolling I can still steer and get off the road if it didn't recover to stay running and then restart it after I pulled over.
 

mrrsm

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Oct 22, 2015
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Last edited:

suncountry72

Original poster
Member
Jun 27, 2016
4
Puerto Rico
Thanks!!! Yesterday night It began to hesitate on Highway cruising from 55 to 60mph. Maybe it's a Ignition coil going bad or a spark plug.. Again there is no code.. Feeling frustrated..
 

mrrsm

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Oct 22, 2015
7,639
Tampa Bay Area
Take a Deep breath...Have a seat... and be encouraged that we'll continue helping you to search for the answers... and right now our investigative band of information can narrow down the search field:

It will help to research (Using the 'Search Forums" button above) for issues involving the CPAS Solenoid - or Camshaft Position Actuator Solenoid .. located on the Passenger Side of the Engine Head... just behind the Power Steering Pump... This solenoid interacts with the Camshaft to Camshaft Phaser relationship for advancing or retarding the VVT or Variable Valve Timing of the Exhaust Camshaft and relies upon the infinite variation in Clean Oil Pressure in concert with the CPS -Camshaft Position Sensor located up near front left area of the lower Timing Cover keeping track of the ACTUAL position of the camshaft at all times... (it is on your left... as you face the engine) right at the left upper front of the Engine Head and... in conjunction with the CPAS... it signals the PCM with inputs from the Crankshaft Position Sensor... and all three manage to affect and actuate 25 degrees of change in the position of the VVT Exhaust Camshaft Phaser under varied driving conditions under commands from the PCM.

If the CPAS Solenoid has become clogged up inside with Dirty Oily Debris in its screens... then it can malfunction and NOT throw any meaningful codes to look at and figure out this problem. Symptomatically, the engine will stagger and hesitate...sometimes at idle...but mostly at highway speeds between 50-65 MPH. The solutions are well covered with the following videos that show you how to Remove and Replace them. Please understand that central to the problem is that the Engine Oil and Oil Filter must be changed FIRST... or replacing them will simply wind up with unsatisfying results when the CPAS immediately re-clogs:

How the CPAS Theoretically Works:

CPAS Specific R&R Videos:

CPS Specific R&R Video:
 
Last edited:

suncountry72

Original poster
Member
Jun 27, 2016
4
Puerto Rico
Take a Deep breath...Have a seat... and be encouraged that we'll continue helping you to search for the answers... and right now our investigative band of information can narrow down the search field:

It will help to research (Using the 'Search Forums" button above) for issues involving the CPAS Solenoid - or Camshaft Position Actuator Solenoid .. located on the Passenger Side of the Engine Head... just behind the Power Steering Pump... This solenoid interacts with the Camshaft to Camshaft Phaser relationship for advancing or retarding the VVT or Variable Valve Timing of the Exhaust Camshaft and relies upon the infinite variation in Clean Oil Pressure in concert with the CPS -Camshaft Position Sensor located up near front left area of the lower Timing Cover keeping track of the ACTUAL position of the camshaft at all times... (it is on your left... as you face the engine) right at the left upper front of the Engine Head and... in conjunction with the CPAS... it signals the PCM with inputs from the Crankshaft Position Sensor... and all three manage to affect and actuate 25 degrees of change in the position of the VVT Exhaust Camshaft Phaser under varied driving conditions under commands from the PCM.

If the CPAS Solenoid has become clogged up inside with Dirty Oily Debris in its screens... then it can malfunction and NOT throw any meaningful codes to look at and figure out this problem. Symptomatically, the engine will stagger and hesitate...sometimes at idle...but mostly at highway speeds between 50-65 MPH. The solutions are well covered with the following videos that show you how to Remove and Replace them. Please understand that central to the problem is that the Engine Oil and Oil Filter must be changed FIRST... or replacing them will simply wind up with unsatisfying results when the CPAS immediately re-clogs:

How the CPAS Theoretically Works:

CPAS Specific R&R Videos:

CPS Specific R&R Video:

Do you recommend to change those parts before anything else? There is no code present and all systems says pass in my OBDII scanner reader.. :smile: Thanks!
 

mrrsm

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Oct 22, 2015
7,639
Tampa Bay Area
Well ...besides the anecdotal experiences of many members here who have replaced BOTH of these items ...but not the CKP Crank Shaft Sensor... You can add me in with that group to testify to the efficacy of this Dual Change-Out Repair. Please invest in an OEM Class CPAS Solenoid and don't go Cheap and buy an inferior after-market brand... as they can give sketchy and unreliable performances. As for the CPS Sensor ...they are all nominal and acceptable... but remember... you get what you pay for and... "Only a Fool Forgets these Three Little Words":

Original Equipment Manufacturer (OEM)

You MUST remove the three bolts holding on the Power Steering Pump or the CPAS Solenoid will not be able to clear it for removal. In a WCS (Worst Case Scenario) you might get away with a serious solvent spray cleaning of the original CPAS Solenoid presently misbehaving inside your engine right now... but empirically... You will see Engine Oil coating the Electrical Connector Plug and dirty old adjacent on the Engine Head...because it is FUBARED... and leaking through the body of the solenoid. Toss it. Replace it. They also suffer from having damaged or entirely missing screens from inside of them.

Finally...Invest in the Best Oil and Oil Filter.... Period. ...Mobil1 5w-30 Motor Oil...with either a K&N, a Mobil1 or an Amsoil Oil Filter before you begin the repair. You will not have to re-set any codes related to this repair unless you change out the CKP Sensor...and that requires a trip to the "Stealership" where they do what is called CASE Re-Learn...followed by a $99 'Wallet-ectomy' and of necessity hand you back the empty wallet. Look at this way... These components are probably overdue for replacement anyway...and unfortunately...on your list of "What the Hell Should I Do Next...".... These two items...are #1 on the runway...


PS....

About these fancy OBD I and OBD II and CAN Readers... Yes... they are great automotive diagnostic AIDS .... However, when it comes to solving problems involving mechanical things that touch each other and wear and tear... their influence on figuring out these subtle problems can often be greatly overrated. You will be a Better Mechanic by using your Common Sense, armed with the stuff inside your Noggin' and by Researching and Reading the posts and Historical Repair Library that is the Heart and Soul of GMT Nation ... No less equivalent to that of The Library at Alexandria before some intoxicated Jackass burned it down!
 
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Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
I'm thinking fuel pressure might be an issue. Check the fuel pressure and replace the filter if it hasn't been replaced lately. A flaky fuel pump might cause stumbles.
 

mrrsm

Lifetime VIP Donor
Supporting Donor
Member
Oct 22, 2015
7,639
Tampa Bay Area
Even though you are are not throwing any codes...IIANM... Recently in a similar thread... @Mooseman cited a problem where faulty O2 sensors can cause an overly rich Fuel-2-Air mixture with a stoichiometric imbalance so rich in fact... that the unburned fuel will cause the CAT to become clogged and soon ruined, with enough of a blockage inside to raise the back-pressure within the cylinders, sufficient to make the engine stall suddenly at idle....

Incidentally... Pay very close attention to the advice offered time and again from @Mooseman... because the Density of his Automotive Knowledge is So Great... that wherever he is walking around up in Canada at any given moment... the surface of the GWN... tilts in his direction ;>)


In the meantime...

The CPAS and CPS issues are the "BEE-BOP and ROCK-STEADY"... of problems worth fighting against... as the TMNT would say...
 
Last edited:

suncountry72

Original poster
Member
Jun 27, 2016
4
Puerto Rico
I'm thinking fuel pressure might be an issue. Check the fuel pressure and replace the filter if it hasn't been replaced lately. A flaky fuel pump might cause stumbles.
My envoy don't have a fuel filter. Not to my knowledge. Or am I wrong?? Uve check everywhere under my Envoy and I didn't find it. Then if not it can be a fuel pump failing right?
 

HARDTRAILZ

Moderator
Nov 18, 2011
49,665
Filter is in tank
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
I hate not seeing the vehicle info without having to go to the profile.
 

Dillyo82

Member
Aug 17, 2012
80
2003 Trailblazer 4x4 LT. 144,000mi. I have had this issue for years now. I did have a p0340 (camshaft). Cleared it and hasn't came back in 2 months. I replaced O2 Sensors, CPAS and cleaned TB. Fuel filter 8,000mi ago. 1700mi on a Synthetic Blend Castrol with an AC Delco filter. Stalling at idle. The "check gauges" flickers as well as oil pressure drops on guage cluster.

Maybe Camshaft Sensor is next, which has to be done at a dealer unless I have a techII or is that the Crank?
 

littleblazer

Member
Jul 6, 2014
9,265
Crank sensor has to be done at a dealer...
 
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gmcman

Member
Dec 12, 2011
4,656
2003 Trailblazer 4x4 LT. 144,000mi. I have had this issue for years now. I did have a p0340 (camshaft). Cleared it and hasn't came back in 2 months. I replaced O2 Sensors, CPAS and cleaned TB. Fuel filter 8,000mi ago. 1700mi on a Synthetic Blend Castrol with an AC Delco filter. Stalling at idle. The "check gauges" flickers as well as oil pressure drops on guage cluster.

Maybe Camshaft Sensor is next, which has to be done at a dealer unless I have a techII or is that the Crank?

The flickering and oil pressure gauge drop could be the result of a low idle before it stalls from low voltage, not that the oil pres gauge really depicts pressure but it's still electrical.

Do you have any codes?

I always strongly recommend a can of BG44K anytime there's a driveability issue like this. This stuff is not snake oil and about the best you can run through your fuel system, also cleans up combustion chamber which is it's primary function.

I also replaced my fuel pressure regulator not too long ago while chasing a few MPG gremlins and it seemed to smooth out my throttle response, not by leaps and bounds but was noticeable.

Edit, sorry I didn't see you have no codes.

Also, check for vacuum leaks, check intake manifold bolts (89 inch pounds, just past snug), large black hose under resonator as well as this port.....

vac1s.jpg

sometimes blocked off but should have a cap on SWB models
 
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Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
Crank sensor has to be done at a dealer...

Not true. You can change the sensor but you need to get a CASE relearn done afterwards at a dealer or shop with a Tech 2 or high end scanner, like a Snap-On Solus.
 

Dillyo82

Member
Aug 17, 2012
80
The flickering and oil pressure gauge drop could be the result of a low idle before it stalls from low voltage, not that the oil pres gauge really depicts pressure but it's still electrical.

Do you have any codes?

I always strongly recommend a can of BG44K anytime there's a driveability issue like this. This stuff is not snake oil and about the best you can run through your fuel system, also cleans up combustion chamber which is it's primary function.

I also replaced my fuel pressure regulator not too long ago while chasing a few MPG gremlins and it seemed to smooth out my throttle response, not by leaps and bounds but was noticeable.

Edit, sorry I didn't see you have no codes.

Also, check for vacuum leaks, check intake manifold bolts (89 inch pounds, just past snug), large black hose under resonator as well as this port.....

View attachment 77215

sometimes blocked off but should have a cap on SWB models

Thanks.
Never heard of BG44K. I usually put in a sale item of fuel treatment about twice a year, but do t have much faith in these.

I found my CPS I bought a year ago today. Going to swap it out this weekend.

Hopefully the truck won't stall again until. It is so hot here in FL and my 3yr old needs AC.

Don't want him and my wife sitting in a hot truck waiting for a Tow in traffic. This is the first time I've considered trading it in. Probably would have already if it weren't for this site. Hope this works!
 

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