Engine stalls intermittently

Hi,

The idea that it happens when cold could be related to the fuel pump. However, if you replaced it last year and it continued to stall, chances are that isn't the issue.

The engine coolant temperature sensor (ECT) can also be an issue. The ECT signals the PCM (main computer) what the coolant temperature. Based on that signal, the PCM determines how rich or lean to make the fuel mixture for the engine to run under certain conditions. I'm not sure where you are located, but if the ECT signals it's 90 degrees F and it's actually 20 degrees F, the mixture will be too lean for the engine to run properly.

If you have a live data scanner, before starting the engine in the morning, check to see what the ECT is signaling. It should be very close to or the same as the ambient temperature. Since you replaced the pump already and the cold weather affects it, this is a very good possibility.

If you look at the attachment, it explains basically what I just described. When first started, the PCM is controlled by a few different sensors (ECT) is what tells it the temp. Once it reaches a predetermined temperature, then the vehicle goes into what is called a closed-loop, and the fuel mixture is determined primarily by the oxygen sensors. That is the point where you have no issues.

Let me know if the ECT is something you can check with a scanner. Also, pic 2 below shows its location. (driver's side front of engine)

Let me know what you find.

Joe

See pics below.

I have tried 7 auto stores, and nobody has a live data reader. I am hoping to borrow one from an old friend if he can find this. Thank you so much for this advice. It has died several random times and must be something related to temperature, since it doesn't do it in the summer.

Hello,

If you want, since you are locating a scan tool, you could check to see if there are any issues with the present sensor. The coolant temperature sensor is located on the left side of the engine. See pic 1

You may want to check to make sure the connection is tight and not damaged in any way. Also, corrosion between the connector and sensor can change voltage signals. Disconnect it and inspect it for corrosion.

Let me know what you find.

Take care,

Joe

See pic below.

You were spot on. I didn't find it right away and paid a mechanic that couldn't even tell me where the sensor was after he said he checked it, so I bought an OEM sensor and did it myself. Workers, no more stalled suburban. Thanks a ton!

Hi,

You are very welcome. I'm glad the problem is resolved, and the vehicle is running properly again.

Take care of yourself and feel free to come back anytime in the future.

I hope you have a nice holiday season!

Joe