Envoy Stalled At Stop Light - 3rd Incidence in 1 year.

[CaptainXL]

Ok folks. I need some input into this stalling issue I have been having. My Envoy seems to stall only after coming to a complete stop. The engine starts right back up after putting it in park. I do notice it stumbles a bit when restarting but it catches and fires. Continues to run just fine after that. Seems to only happen on a 80+ degree days with AC on. Has happened more towing than not. Could this be vapor lock?

I have gone through just about everything on this vehicle short of hooking it up to a Tech2 but somehow I don't think that will show anything since it only happens once in a while. Does anyone have any idea what might be happening here? I have read a few articles that say my PCM might need programming to the latest calibration but I think I already have the latest. Any input is appreciated.

 

[CaptainXL]

Ok, after reading a bunch of threads over on the OS and here I think i am going to replace the the Camshaft Position Sensor as Fishsticks indicated.

A faulty cam position sensor caused power issues and the occasional stall for me. Would always start right up and be fine afterwards. It threw no codes.

The one under the sprocket cover. My CPAS is original still.

 

[jrSS]

I had his same issue right after sarting .....backing up stopped to put in D and it would stall.(on my voy). Cleaned the throttle body and never did it again.

 

[CaptainXL]

I think I am on to something. I disconnected the camshaft position sensor harness and the truck idles and runs better than ever with much better throttle response. Already done the tb clean twice about 10k ago.

 

[christo829]

Does rather sound like the sensor, but could also be the camshaft position actuator solenoid itself.
Do you see any oil leakage around the electrical connector on the solenoid? How's your oil? Old, dirty
oil can screw up the CPAS response to the signal the PCM sends, based on what the sensor tells it.

At least the sensor is cheap. If it doesn't solve the issue, next thing to do would most likely
be the solenoid.

If you have access to a scan tool that can see real time sensor data, you can watch the relationship between
what the PCM is calling for (based on the sensor information) vs what the solenoid is giving. You might
notice it not adjusting fast enough, or adjusting up, but staying there instead of coming back down.

Good Luck!

Chris

 

[CaptainXL]

Does rather sound like the sensor, but could also be the camshaft position actuator solenoid itself.
Do you see any oil leakage around the electrical connector on the solenoid? How's your oil? Old, dirty
oil can screw up the CPAS response to the signal the PCM sends, based on what the sensor tells it.

At least the sensor is cheap. If it doesn't solve the issue, next thing to do would most likely
be the solenoid.

If you have access to a scan tool that can see real time sensor data, you can watch the relationship between
what the PCM is calling for (based on the sensor information) vs what the solenoid is giving. You might
notice it not adjusting fast enough, or adjusting up, but staying there instead of coming back down.

Good Luck!

Chris

Already replaced cpas a year ago

 

[christo829]

Already replaced cpas a year ago

Could still have gone bad, gotten clogged, or be leaking. If the internal seals have started leaking
on it, the oil can get in to the electrical connector and cause problems.

Was it AC-Delco? Some members have had problems with aftermarket ones, though they seemed
to see problems right after the change, not a year later.

What is odd is that it ran better without the sensor. In theory, it should perhaps run OK at idle, but
it should run worse when the timing needed to be adjusted during driving. And, it should have thrown a code
that at least reflected a mismatch in sensor vs solenoid position, much less the actual absence of the sensor
while it was disconnected. If it didn't, that might suggest a wiring issue, but that's definitely supposition.

Cheers-

Chris

 

[CaptainXL]

I think I got a bad valve on 6. I swapped coils on 4 and 6 and I get misfires at idle on 6. I hooked the cps back up and the CEL that came on went off. looks like I need to do a leakdown test next.

The truck ran good until the CEL came on. Which was a day after disconnecting the cps.

 

[CaptainXL]

I read on another forum that there is a tsb for this type of misfire. It really doesn't need to be addressed unless it misfires while driving...which it isn't. So I am just going to live with it for now until I get a CEL for misfire.

 

[CaptainXL]

Truck Almost died today while in driveway reving engine at 2000 rpm for about 30 seconds. Check engine light came on. Getting code if there is one. The only way to describe it was as if someone turned off the ignition and then back on really quick.

 

[MacMan]

You never said whether or not you've done a proper throttle body cleaning w/ battery disconnected.

 

[jrSS]

I think I am on to something. I disconnected the camshaft position sensor harness and the truck idles and runs better than ever with much better throttle response. Already done the tb clean twice about 10k ago.

Yup he did^^

 

[CaptainXL]

I checked the codes and I have a lingering P0526 code from when I replaced the fan clutch a week ago. No new codes unless this is a new code but I doubt it. Will erase and wait again I guess.

 

[Mypetropig]

I had a very similar issue less the misfires. It was very erratic and like you said it would only do it when slowing to or completely stopped. It finally threw a code for the cam position sensor, since replacing it I have had no further issues. IIRC it was about $25 at rockauto.

 

[CaptainXL]

I had a very similar issue less the misfires. It was very erratic and like you said it would only do it when slowing to or completely stopped. It finally threw a code for the cam position sensor, since replacing it I have had no further issues. IIRC it was about $25 at rockauto.

Well my truck definitely hasn't totally stalled since replacing my Camshaft Position Sensor but it has stumbled once and almost died like I described.

I can drive around all day with the Camshaft Position Sensor disconnected and I notice no problems. Perhaps if I left it disconnected for a few more days I would eventually get a CEL. Something like disconnecting the MAP sensor gives a more immediate CEL.

 

[CaptainXL]

Went out to my truck and let it idle with the AC on. Dang thing almost died again after about 20 seconds of letting it run!

Seems to be happening more often now. Check engine light came on but no code. I am just gonna let the thing die. Hopefully not in traffic!

Just got done reading a bunch of old posts back on the OS. Bill explained how this has been an issue and suggested to someone to replace the TB. But instead of getting a new one I might just look for a junk TB and see if anything changes.

 

[MacMan]

Yup he did^^

I was looking for confirmation that he had the battery disconnected for at least 35-40 min. when he did the cleaning.

 

[CaptainXL]

I was looking for confirmation that he had the battery disconnected for at least 35-40 min. when he did the cleaning.

Yep. Left it disconnected overnight

 

[MacMan]

Yep. Left it disconnected overnight

And the TB was removed from the engine and both sides cleaned w/ TB spray and a rag or old toothbrush, right?

Sorry for extra questions....just eliminating any possibilities.

 

[CaptainXL]

And the TB was removed from the engine and both sides cleaned w/ TB spray and a rag or old toothbrush, right?

Sorry for extra questions....just eliminating any possibilities.

Yes.

The question i have is why would the check engine light come on and have no codes?

 

[MacMan]

Yes.

The question i have is why would the check engine light come on and have no codes?

That's a weird one, for sure.

 

[CaptainXL]

My Envoy stalled again yesterday while at a stop light with the A/C on. I was just about to give it gas when it totally stalled. Now here is what I think is the important part....

I tried to restart it in park and it would crank over but wouldn't start. I had to try three times. Previously it would start right up. This issue seems to be getting worse. About the only thinkg I can think of that might wear and get worse is the fuel pump. Any suggestions? I would like to keep a running log of these issues as I am having so please forgive me about keep this thread up to date. It is my hope that it might help out someone down the road. Thanks.

 

[TB2004]

Hey All hope this helps. I recently started having this problem and found my fan clutch was going bad, the high side a/c pressure would kick the relay out but the pressure was still high when it came back on. Not enough air coming through radiator at idle and slow speeds. Also its possible the evap cannister is full from the fuel tank and the purge valve will open and cause a too rich mixture, Then again it may be time to clean the throttle body too. I will be replacing the fan cluth with a heavy duty Hayden 3200 hopefully this weekend, throttle body cleaning in the near future. Thanks for starting this site, wondered why the other seemed so stale... 105+ temps lately have made this stand out with low cooling a/c temps at low and idle speeds...

 

[khill]

Yes.

The question i have is why would the check engine light come on and have no codes?

The check engine light indicates that some module in the vehicle is throwing a code. Most code readers that are not TechII or advanced computer models can only read generic or powertrain codes. There could be another control module giving off an error that can only be read by an advanced reader. My advice: find a mechanic with a TechII capable reader or just take it to the dealer and say you wont pay if they cant tell you what it is, my dealer was pretty good on that point.



OBD codes:

P = Powertrain
B = Body
C = Chassis
U = Undefined


Good luck,
Keith

 

[CaptainXL]

The check engine light indicates that some module in the vehicle is throwing a code. Most code readers that are not TechII or advanced computer models can only read generic or powertrain codes. There could be another control module giving off an error that can only be read by an advanced reader. My advice: find a mechanic with a TechII capable reader or just take it to the dealer and say you wont pay if they cant tell you what it is, my dealer was pretty good on that point.



OBD codes:

P = Powertrain
B = Body
C = Chassis
U = Undefined


Good luck,
Keith

I was thinking the same line of logic however if there really was a permanent issue the CEL would stay on. I wonder if there is a way for the dealer to lookup code history even after disconnecting the battery. Not sure if our pcms are so engineered.

Alternatively it could be that the cell came on because the pcm actually reset itself and as a preliminary check tests the cell each time. I did some research and found that there are at least 2 pcm revisions with different and newer part numbers.

 

[khill]

I was thinking the same line of logic however if there really was a permanent issue the CEL would stay on. I wonder if there is a way for the dealer to lookup code history even after disconnecting the battery. Not sure if our pcms are so engineered.

Alternatively it could be that the cell came on because the pcm actually reset itself and as a preliminary check tests the cell each time. I did some research and found that there are at least 2 pcm revisions with different and newer part numbers.

There are a whole slew of B and U codes (though I'm not sure if they all apply to the GMT360) that relate to comm interruptions with modules so that could explain the on or off behavior, or your truck could be haunted with ghosts and gremlins. Either way it's annoying as hell, I know. Make friends with a mechanic with a TechII and you'll at least have that peace of mind. I have a family friend at a dealership who does this for me, unfortunately he can't do much else under the radar, but the availability of a TII scanner is huge in itself.

 

[Archimedes]

I think I am on to something. I disconnected the camshaft position sensor harness and the truck idles and runs better than ever with much better throttle response. Already done the tb clean twice about 10k ago.

I disconnected my camshaft position sensor after reading your post. The truck accelerates better, has more immediate response and overall runs better. Have you left yours disconnected long term? What has been your experience with it?

 

[CaptainXL]

I disconnected my camshaft position sensor after reading your post. The truck accelerates better, has more immediate response and overall runs better. Have you left yours disconnected long term? What has been your experience with it?

You need a new sensor more than likely. The variable camshaft phasing will not work properly without it.

 

[gmcman]

I would pull the plastic cover in front of the motor and make sure you haven't jumped time

 

[CaptainXL]

I would pull the plastic cover in front of the motor and make sure you haven't jumped time

Curious gmcman, never done this before. Not aware of any plastic cover either. Can you provide a procedure or link?

 

[gmcman]

The black cover with the oil fill cap

 

[CaptainXL]

The black cover with the oil fill cap

Uh. Yeah. That's the valve cover. Its not a simple matter of just "takin it off" to inspect. The intake manifold has to be removed as well which is a long process in itself.

 

[gmcman]

Uh. Yeah. That's the valve cover. Its not a simple matter of just "takin it off" to inspect. The intake manifold has to be removed as well which is a long process in itself.

Sorry bout that...I thought for some reason the front of the cover was separate.

 

[CaptainXL]

Sorry bout that...I thought for some reason the front of the cover was separate.

No problem. Just didn't want someone getting a bright idea that its easy and get mad at us for leading them down a particular path.

 

[gmcman]

What makes me think of the cam timing is when you remove the sensor connection, it runs better. Almost like the actuator is over compensating when it thinks it's operating normal.

 

[CaptainXL]

All I know is that after I replaced my camshaft position sensor last year I have not had any stall issues. Regardless of how it runs it needs to be connected. I will disconnect mine and see how it runs but will reconnect. Would like to see what code pops up for the sake of science. Probably going to get p0340.

 

[seanpooh]

My truck also dies in idle when I have the AC on, and it doesn't even work half the time.
So I changed to the AC bypass belt.

I known for a fact and I told my GF, don't use the AC in idle, especially at a cold start. My RPM will drop, surge back up until the truck dies off which doesn't take long. Same situation you are in. Throttle body clean or not, new engine mounts, didn't matter. Now that issue is behind me, got rid of AC completely.

My guess would had been the AC clutch but you're having codes... to tell you the truth, 10K miles without a TB cleaning too long for me and well over due.
Also you're having a hard start too and SES light...

Try removing the belt, then start and let idle (with your sensors still attached). If it croaks, then we have to poke around some more. Hard starting is usually related to fuel delivery which was previously mentioned.

 

[CaptainXL]

Engine stalled again at idle in park. Cold start. Tried to restart immediately but I had to crank for 5 seconds. Issue seems to be getting worse. Wonder of my crank sensor or fuel pump is going. I get no check engine light.

 

[gmcman]

Are your fuel trims deep into the negative range? Were'nt you having low compression issues before?

 

[CaptainXL]

What are you getting at?