2014 2LT Convertible Stalls at Idle from Cold Start - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

wardbg · 04-30-2018, 11:54 PM

Greetings!

I just picked up my first Camaro, a 2014 2LT Convertible. Shortly after I got it home, it started stalling after about 1 minute of idling from a cold start. After it stalls, I am able to start it again. It then idles smoothly and drives without any problems. If I start it again within a few hours it does not stall.

This is a low-miles car for the year and so I suspect also that it may have spent some time sitting. I got it with 3,2xx miles as a 2014 just this month.

There are no codes or warning lights although right at the moment it stalls the "Service Stabilitrak" display comes on momentarily and then disappears. If I manage to start driving or hold the rpms higher, around 2k for the first minute, the engine stumbles like it will stall but then keeps running.

To try to diagnose it, I connected my phone with the Torque app to my OBDII adapter and logged all sensor data that had anything to do with fuel or air during cold starts. I found that the "Evap system vapor pressure" would steadily decrease after a cold start. The stalling happens when this value reaches its minimum. The fuller the gas tank, the more quickly this happens.

What I think is happening is that at a cold start, the car is running an evap system vacuum test by closing the vent solenoid, opening the purge solenoid and using the intake vacuum to pull a vacuum on the evap system. Then, when the necessary vacuum is reached, the purge solenoid is supposed to close and the rate of pressure normalization monitored. I suspect I may have a sticking purge solenoid that is not closing fast enough and that the resulting extra air is causing the stall. If the car is not cold, the test doesn't run and that's why I only have problems with cold starts.

Before I replace the purge solenoid, I wanted to see what the community would suggest. Thanks in advance for your help.

wardbg · 07-28-2018, 05:34 PM

It has been awhile since I posted this and we have moved in the meantime but I wanted to follow up in case anyone else has the same issue. I eventually took my car to a Chevy dealer to diagnose. They found an internal communication error in the ECU. The fix was replacing the ECU. After this, the problem disappeared. Also, apparently my use of an OBD II logger when I was trying to diagnose the problem myself spread the pin sockets on the connector initially preventing the factory Chevy plug from connecting. Fortunately they were cool about this and fixed the connector. I hope this helps someone else.

04-30-2018, 11:54 PM	#1
wardbg Drives: 2014 Camaro 2LT Convertible Join Date: Apr 2018 Location: Alexandria VA Posts: 5	2014 2LT Convertible Stalls at Idle from Cold Start Greetings! I just picked up my first Camaro, a 2014 2LT Convertible. Shortly after I got it home, it started stalling after about 1 minute of idling from a cold start. After it stalls, I am able to start it again. It then idles smoothly and drives without any problems. If I start it again within a few hours it does not stall. This is a low-miles car for the year and so I suspect also that it may have spent some time sitting. I got it with 3,2xx miles as a 2014 just this month. There are no codes or warning lights although right at the moment it stalls the "Service Stabilitrak" display comes on momentarily and then disappears. If I manage to start driving or hold the rpms higher, around 2k for the first minute, the engine stumbles like it will stall but then keeps running. To try to diagnose it, I connected my phone with the Torque app to my OBDII adapter and logged all sensor data that had anything to do with fuel or air during cold starts. I found that the "Evap system vapor pressure" would steadily decrease after a cold start. The stalling happens when this value reaches its minimum. The fuller the gas tank, the more quickly this happens. What I think is happening is that at a cold start, the car is running an evap system vacuum test by closing the vent solenoid, opening the purge solenoid and using the intake vacuum to pull a vacuum on the evap system. Then, when the necessary vacuum is reached, the purge solenoid is supposed to close and the rate of pressure normalization monitored. I suspect I may have a sticking purge solenoid that is not closing fast enough and that the resulting extra air is causing the stall. If the car is not cold, the test doesn't run and that's why I only have problems with cold starts. Before I replace the purge solenoid, I wanted to see what the community would suggest. Thanks in advance for your help.

07-28-2018, 05:34 PM	#2
wardbg Drives: 2014 Camaro 2LT Convertible Join Date: Apr 2018 Location: Alexandria VA Posts: 5	Follow Up - Found/Fixed the problem It has been awhile since I posted this and we have moved in the meantime but I wanted to follow up in case anyone else has the same issue. I eventually took my car to a Chevy dealer to diagnose. They found an internal communication error in the ECU. The fix was replacing the ECU. After this, the problem disappeared. Also, apparently my use of an OBD II logger when I was trying to diagnose the problem myself spread the pin sockets on the connector initially preventing the factory Chevy plug from connecting. Fortunately they were cool about this and fixed the connector. I hope this helps someone else.