Engine stalls when at a stop randomly

Hi,

When this happens, does it seem like you turn the key off, or does it run rough and then slowly stall? Does the engine idle speed maintain around 700 rpms?

There could be a few things causing this kind of issue. First, something as simple as an engine vacuum leak can cause it. Also, a dirty or faulty idle air control valve can do the same. The IAC is responsible for maintaining the engine's idle speed. Actually, Hyundai refers to it as an Idle speed actuator (ISA). It is located on the throttle body. See pic 1 below.

Here is what I suggest: First, check for vacuum leaks. Here is a link showing how it's done:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

If nothing is found, consider servicing the ISA. Here is a link that explains how to service one:

https://www.2carpros.com/articles/idle-air-control-valve-service

Let me know if you have ever noticed black smoke from the exhaust as well. Also, tell me how it runs off idle. If possible, record what it's doing so I can see and hear it. That may help me.

Take care,

Joe

See pic below.

It's the equivalent to turning off the key. The speedometer also acted weird this one time in the video that makes me believe firmly that it's electrical.

Sorry I thought that video had it cutting off. But it does show the speedometer fluctuating and smooth idle as well as revs. Next time I'll film it shutting off. I should also add that 1 time when it failed to start the speedometer was maxed out at 130 MPH.

Hi,

I watched the video and certainly saw the speedo. I agree it is likely electrical. The PCM (powertrain control module) is located under the dash center. Have you checked to see if there are any loose connections? Also, there could be corrosion or damage that can cause issues with the connector.

I attached the only pic I could find showing the PCM location. If you haven't, check to make sure everything is tight as far as wiring. Also, inspect the wiring and connector to make sure there is no evidence of wire damage and that none of the connector pins are pushed in or corroded.

Let me know.

Joe

See pic below.

The car is currently in a different shop due to a small drivetrain leak. They are also going to diagnose the issue. I'll take a look if they can find it. I'll let you know what is said.

Hi,

Thanks for the update. It's appreciated. I look forward to hearing what is found.

Take care,

Joe