2004 gmc envoy stall at idle issue

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#1
Im having an intermittent problem on wife's 04 envoy, sometimes stalls out while idle at red light or in drive way, seems to be when a/c compressor kicks on. (Also tach. and oil pressure gauge stops working or reads inaccurate) I have done some research and seems to be a common problem, I found no solution. Not shooting any codes. Any ideas, Thanks in advance. So far I have:

-cleaned throttled body
-replaced both front motor mounts
-changed relay for smog pump
-new gas tank (evap leak)
-new fuel pressure regulator
-camshaft control solenoid (dealership)
-fuel injectors serviced
- upstream O2 sensor

**Brought back to dealership, had for 6 days said they couldn't find any problem. When I picked up stalled on the spot. They still cant find a problem.
 
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#2
Is this the 4.2L?
Is the tach oil pressure ALWAYS inop or related to stall?
What exactly is " inacurate"?

GM
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This PI was updated to include models through 2007. Please discard PIT3116.


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The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:
Engine may stall with the air-conditioner on and or while adding additional loads to the engine at idle. An example of an addition load would be turning the steering wheel left or right with the air-conditioning on. This type of stall usually occurs during idle or slow parking lot maneuvers. This concern may not set any diagnostic trouble codes.

Recommendation/Instructions:
Clean the throttle body bore and the throttle valve plate using a clean shop towel with GM top engine cleaner, GM P/N 1052626 (Canadian P/N 993026) or AC-Delco Carburetor Tune-Up Conditioner, P/N X66-P, or an equivalent product.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance.
 
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#3
Yes, it is the 4.2L. I believe the oil pressure gauge is possibly out of calibration usually it points from 6" oclock sometimes 9". The rpm sometimes jumps around. Does not seem to be related. (Engine does not surge in relation to needle movement) I, as well as dealership have cleaned the throttle body. What you wrote describes issues perfectly.
 

Gus

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#4
Is this the TAC system(no throttle cable)?

If yes, after cleaning the throttle body, with the key out of the ignition, remove the neg bat cable, and then remove the pos bat cable....then hold the ends of both cables together(this resets all modules) for a minute....

Re-attach the pos cable, and then the negative cable.....see if this helps.....
 
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#5
Ok, I will try. Also I left out some info. The Dealership also reprogramed computer. If disconnect the battery I wont lose pcm and have to get reprogramed?
 
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#7
I have disconnected the battery for over an hour when I cleaned throttle body about 3 weeks ago before i took it to dealership, I will try again when wife gets home. In the mean time Im searching for other possible solutions to this issue. Every forum I have found say that 99% of the time its a dirty TB, but between myself and stealership That shouldnt be the problem. Any thing else you guys think I should try? Thanks again.
 
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#8
Did you read Gus's reply?....After you disconnect the battery cables you have to touch the 2 ends together...touch the positive to the negative....Jim
 
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#9
Yes, and I will give that a shot when wife returns just trying to get all info. I can while on the cpu. Is it possible that the throttle body (stupid fly by wire) is acting up? Im not getting any fault codes. Or maybe poor alternator/battery? Just trying to eliminate all possible items.
 
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#10
Assume cleaning the TB refers to any binds in the throttle vane or servo motor that drive it. Any binds here will cause that motor to hunt. Is this that private, do you call that clean scenario? Get down and give me 50! And of course hunting will give you the exact symptom you have.

Then that potentiometer under the gas pedal, and erratic wiper contact will drive the servo motor nuts, can be checked out with an ohmmeter. Or dirty electrical contacts. Servo motor must follow that pot.

This system gave the cruise control a giveaway system, everything is there. Unless you purchased say a Cruze LS, came out with a button less steering wheel, guys figured that out, replace with an LT steering wheel to get those buttons and works great. Not giving LS owners cruise is costing GM even more money, new dies for the steering wheel and another stock item to inventory. Crazy.
 
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#12
Something to consider-- a intermittently stuck open EGR could cause your stalling.

It would have nothing to do with tach or oil pressure, but those might be separate issues.

You could try cleaning it or even blocking it off for a short temporary test.

Blocking it would require fabricating a plate to be installed between the EGR and the intake so that no exhaust gases could enter the intake. If that solves your problem, the EGR must be fixed of replaced and the plate removed. If not, at least you have eliminated the EGR as the culprit.
 
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#13
I am experiencing the same concern with my wife's 2004 Envoy XUV. Idle stalls, or stalls with A/C compressor engagement, or turning in parking lot. I am a technician at a GM dealership, and cannot seem to figure this concern out. Scanned systems, and found no relevant codes. I know there are bulletins all over SI addressing this concern, and they advise to clean the throttle body, well I clean her throttle body religiously, and perform an idle learn procedure after every cleaning, so I know for a fact it is NOT related to a "dirty" throttle body. Software calibrations are up to date, and I'm at my wits end with this problem, and not sure what is the cause.
 

billr

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#14
Do you have access to the dealership's Tech2 (or better)? I would think live-data could help you out here. Look for things like IAC position, spark timing, TPS, EGR position and command, knock retard, etc. Doesn't the dealer stuff even let you activate the EGR and IAC to test them out?

TCC slip, too. Maybe the TCC simply isn't unlocking.
 
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#15
I have access to a TECH2, and also have my own personal MDI2, a laptop, and tech2win, problem is getting the problem to duplicate when you're watching it. It doesn't do it often enough to predict, and can't find a solid rhyme or reason for when it occurs.