2013 ATS 2.5L Auto - Dies / stalls at operating temp, starts right back up

[2013ATS]

2013 ATS 2.5L with 6-speed auto trans, 54k miles, no DTCs.

After the engine reaches operating temp and after a few stops, the engine will intermittently die. The car will start right back up after it dies. Also, at a cold start, there is a brief rattling type noise (like a loose metal shield) and the engine sometimes idles a little rough before smoothing out.

Recent repairs: Throttle position relearn (twice), both VVT actuators (due to DTC), new #3 coil pack (misfire confirmed), new crank position sensor (no DTC, just throwing parts at the symptoms). Also, at 45k miles and about a year ago, the torque converter was replaced under a TSB regarding a known trans / TC shudder issue.

Anyone had an issue with this engine and heavy carbon buildup on the valves? I'm hoping this is not the cause, but it could be. Proper fix is removing the head for a walnut shell blasting to clean the valves and seats.

Anyone found a fuel system cleaner that has proven to clean their valves of carbon buildup? I've read that the Techron additive is among the better ones.

Anyone installed a catch can and noticed a difference (i.e. oil the catch can at each oil change)?

Here are my current thoughts on next steps:

1. Buy a scope or take it to a shop to inspect the valves for carbon buildup

2. Clean the MAF and throttle body with the appropriate cleaners, disconnect battery briefly, then perform a throttle position relearn again

3. Replace cam position sensor even thought the symptoms do not match well and there is no DTC for it.

4. Take it back to the dealer and have them check and test the torque converter solenoid and verify no issues with the trans. Torque converter replacement is still under warranty.

If you've experienced this, please advise what you did to fix it. I'm quite frustrated.

[Bruce Nunnally]

if the engine is dying, it is losing fuel, spark, or air.  I suggest try to sort out which one

[2013ATS]

4 hours ago, Bruce Nunnally said:

if the engine is dying, it is losing fuel, spark, or air.  I suggest try to sort out which one

Agree in principle, I just don't have the equipment to test for these and am trying to minimize the shop / repair expense.

Since the engine starts right back up after stalling, that would possibly suggest the fuel filter (in the tank), but not the fuel pump. Whatever buildup was clogging the filter would settle due to lack of fuel pump pressure, but in theory, the car should stall shortly after that again.

Air filter is like new and very clean. It seems spark / ignition could be ruled out because parts like this should remain in their failed state for a while after the engine dies.

The spark plugs only have 54k miles on them, and when the dealer replaced #3 coil pack, they suggested also also replacing the plugs. Could it really be that simple? That's a relatively cheap item so I will add this to my list of next steps. I'm the second owner and have only had the car a little over a year, prior owner was in Brownsville, TX (very hot and dry climate).

Edited April 26, 2021 by 2013ATS

[2013ATS]

Good news, found the problem. So simple, can't believe it. The air intake hose that connects to the air filter box was partially off and, obviously, the clamp wasn't screwed tight. I had recently checked the air filter and remember being distracted with several other things, then when back to finish the job, obviously I didn't notice this hose & clamp were loose before closing the hood. Properly secured it and tightened the clamp, have driven the car several times since and all symptoms are gone.

[Bruce Nunnally]

Oh nice simple fix.  Odd that would cause the engine to die completely but good the symptoms are gone.

 

[2013ATS]

15 hours ago, Bruce Nunnally said:

Oh nice simple fix.  Odd that would cause the engine to die completely but good the symptoms are gone.

 

Yes, but it makes sense. It's warm and humid in SE TX right now. So as the engine bay warmed up, hotter and an excess amount of air was being pulled into the engine after (downstream from) the MAF, so the air/fuel mixture was different than what the ECM measured.