Having an issue with my 2017 Kia Forte. It has 93k miles.
When I'm at low speeds (< 15mph) and let off the throttle, the car will stall and shut off. A few interesting things that I've noticed:
- The issue doesn't happen every time i let off the throttle
- It only happens after the car has been running for about 30 minutes (and in the hour or so after driving it if I drive it again)
- There are no codes and the check engine light is not on
- It's never happened at high speeds
- Sometimes, when trying to turn it back on, it will struggle to turn over
- Other times, it turns right back on
- If I catch it right as it's going to turn off, I can put it in Neutral, give it a lot of gas, and it will kick back into normal operation without shutting off
- It doesn't idle rough
I've done a couple things to try to address the problem:
- I replaced the MAP Sensor with a new one. This didn't affect the problem at all
- I cleaned the throttle body (pulled it out and cleaned both sides). It was fairly dirty. Unfortunately, that didn't fix the problem either. However, it now seems to struggle a lot more to stay on instead of turning off right away. (The RPM will drop to ~500 and jump a few times to ~900 before losing the battle and shutting off).
I'm pretty lost on what to do next. I would appreciate any help.
Wanted to give an update, in case anyone stumbles on this in the future:
After getting the battery tested, I figured I would replace the spark plugs since I hadn't done that since taking ownership of the vehicle. I'm pretty sure the spark plugs were the factory originals (they were OEM branded), because they looked pretty beat up.
After changing the spark plugs, the issue went away!
Sometimes it's just the simple things, I guess.
You could record some live data while the problem happens and look at it afterwards for problems.
I have done that a few times but didn't see anything interesting. All values I was watching were normal right up to when it shuts off.
Not sure if it's just me not knowing how to read the data or not looking at the right metrics.
I was tracking:
- Calc. Engine load
- Evap System Pressure
- Intake Manifold Absolute Pressure
Happy to share exports from BluDriver if it is helpful
Fuel trims?
When I'm at low speeds (< 15mph) and let off the throttle, the car will stall and shut off.
Needs to be scanned so we can offer better guidance.
- I cleaned the throttle body (pulled it out and cleaned both sides).However, it now seems to struggle a lot more to stay on instead of turning off right away.(The RPM will drop to ~500 and jump a few times to ~900 before losing the battle and shutting off).
If the battery was disconnected long enough when you cleaned the throttle body, it might just need a relearn procedure.
Sorry, I should've made that clear in the op. I scanned the car with a BluDriver OBD2 tool and didn't come up with any codes.
> If the battery was disconnected long enough when you cleaned the throttle body, it might just need a relearn procedure
I, uh, didn't disconnect the battery when cleaning it. Would that cause an issue?
I didn't remove the coolant lines from it, but I did unplug the electrical harness to get better access to it.
Disconnecting the battery before working on anything with an electrical component is a good practice and you might have done so. Unless something shorted you should be good.