Nearly stalls when braking hard

XtheEdgeX · September 13, 2023

Hello All. 2014 Silverado LT 2WD w/ 5.3 engine. Only 43,000 miles.

I've had this issue for a while and it's not been figured out yet. When my truck was under warranty, the dealership looked at it a few times and couldn't figure it out. Since there were never any codes, they wouldn't troubleshoot any further.

It started having a rough idle early on and my mileage dropped some. The dealership acknowledged the rough idle but no solution. They did the induction cleaning(?) but it didn't help.

When the engine is warmed up, and if I come to a faster than normal stop, the engine will die down like it's going to stall, then it will pick back up. The rough idle is always there. There have been 2 times that the engine has actually stalled, but it starts right back up no problem. There are no stall issues when braking normally. Just the constant rough idle.

I've looked on the internet many times for research, and the only thing I've found that sounded similar was someone had an issue with their Evap purge valve.

Any ideas?

Snowcamo · September 14, 2023

Vacuum leak some where. Just a guess. Maybe intake gaskets.

superdave160 · September 24, 2023

I have a similar issue. My truck sometimes dies when maneuvering around parking lots when making small inputs to the gas pedal and then releasing. For instance, if I back out of a parking stall, it will die when I take my foot off the gas pedal to press on the brake pedal. When I'm backing my camper, it dies almost every time after I take my foot off the gas. I keep getting told vacuum leak as well, but I have been unable to find any leaks. I have sprayed ether and MAF cleaner around the intake manifold and could find no issues. While idling, the RPM would suddenly drop and the motor would stutter. I cleaned the MAP sensor and the EVAP vent solenoid valve with no success. Next, I disconnected the fuel vapor line from the EVAP vent solenoid valve and capped the port on the solenoid valve. It appears to idle much smoother and I have not had it die while driving. I just did this yesterday, so it's still too early to say for sure.

If the issue appears to be gone after driving for a week or so, I'll have to figure out what the issue with the EVAP system is. It could be the purge valve, the vent valve, the EVAP canister, or maybe a cracked line.

2017 Silverado WT, 5.3L, 6 speed transmission. 46,000 miles.