*New update please help* Stalling and hesitating in Kia Sorento after getting gas

Question

I have a 2011 Sorento that has been a mystery. It started hesitating and sort of hiccuping seemingly randomly a few months ago. Fast forward and we have seen three mechanics and there are no codes and they say it looks great, even after stalling. More recently it's been getting worse and I going to take it back in soon. The Kia dealer I took it to says it was bad gas (we started suspecting this was happening after filling up but weren't positive at the time). I now am positive it has to do with getting gas as it has gotten to the point where sometimes it dies while leaving the gas station. It only dies while coming to a stop or idling. The other day I was able to get it home and then tried to turn it off and restart and it almost immediately shut off again. Later, I had to reposition the car and it worked but I noticed that the vibrations were pretty bad in drive. I haven't driven it since. Typically it smooths out after driving for a short time and I will have no issues until (possibly) the next fill up. This same Kia dealer previously replaced the charcoal canister and canister close valve several months ago (before the stalling/hesitating started) because we were unable to pump gas because the canister had broken open. When I took it in for the recent issues to them, they said those are the first parts they checked. Everything I have read online says that this is very likely the purge valve. I asked them about this and they said that it would show codes for sure if that was the case. I'm hoping it shows codes now because I am at my wits end. We started thinking maybe it really was just bad gas after having this issue going to WaWa and then two times not having the issue at a Chevron. But no way this is the case as we have now had issues at that same Chevron and a Shell station very far from my house. Please help, advice is very appreciated.

UPDATE The mechanics are saying the canister assy and all associated parts are full of gas. They are claiming this is my fault for over filling the tank. I don't over fill the tank. They want almost $3000 to repair everything and deny it is a defect in the previous repair of the canister close valve and charcoal canister they replaced a few months ago. I think they don't want to cover their work. I was reading that the canister close valve can definitely cause this. Any advice would be greatly appreciated.

Answer 1

It's a defective main computer (Electronic Control Unit, or ECU). Kia has known about the problem since at least 2014 and issued a recall. Have the dealership check the VIN (Vehicle Identification Number) and see if you are eligible. See this page for further information.

Answer 2

Here are some other possibilities:

-Low fuel pressure, dirty or defective fuel injectors, or broken fuel pump: The fuel pump is responsible for transferring fuel from the tank to the engine. A malfunctioning fuel pump can result in low fuel pressure, which means that there is an inconsistent stream of fuel to the engine. At high speeds this doesn’t matter as much, but at low speeds a temporary pause in the fuel stream is enough to kill the engine. The fuel injectors are responsible for spraying a measured amount of fuel that is ignited by the spark plugs at the proper time. Injectors can become clogged or dirty over time resulting in erratic spray or no spray at all.

-Bad oxygen sensor or mass flow sensor: The oxygen sensors and mass flow sensor determine how much oxygen is entering the fuel stream, and helps the vehicle adjust the air-to-fuel ratio. If there is too much or too little oxygen, your vehicle will not have optimal power. Just like with low fuel pressure, the car will continue to operate at driving speeds, but this suboptimal power won’t be able to fuel the vehicle as it slows down.

-Loose or corroded wires in wiring harness: An inconsistently firing ignition will result in an easily stalled engine. If the wires don’t have consistent, constant, and reliable connection with the ignition circuit, the vehicle can lose voltage quickly, and it won’t have the power it needs to keep running as you slow down.

-Faulty idle air control actuator: The idle air control actuator controls the engines RPMs when it is idling. This actuator receives information from the electronic control unit (ECU) so it knows at what RPM to keep the engine for a smooth and safe idle. When the actuator malfunctions, the engine gets no signal for idling speed and stops working.

-Clogged or restricted EGR Valve: If your EGR valve is clogged, dirty, or defective it can cause your car to stall, idle erratically, or sputter, depending on whether it is stuck open or closed.

Answer 3

Read this thread. Many Kia models/years stall without an ECU problem or a CEL code. Most common solution is to replace the crankshaft position sensor. The crankshaft sensor can be purchased for about $40 and can be replaced by yourself or by any old mechanic for under $100.

The second most common part to fail is the fuel pump. The replacement cost is about $600 ($500 parts, $100 labor).

Answer 4

Regarding the UPDATE in the original post:

Take the mechanic to small claims court. You really have nothing to lose.