I have a 2009 with a NA 4.2L V8 with a strange problem I can't figure out.

When the car is warmed up, and I cut it off, if I try to restart it, it sputters and dies as soon as it cranks.

If I start ut up and rev the motor for a few seconds, it starts running right, idles just fine, and I can drive it.

I never have any problems starting it when the engine is cold, and once I get it past the first few seconds, it runs great. I drive it everywhere.

Anyone have any idea what could be causing hot restart issues?

 

Possibly a temp sensor (ECT / IAT) - check via OBD.

 

I do have an intermittent Check Engine Light that only comes on in cold weather. Scanner said the thermostat temperature was lower than expected.

If it's a temperature sensor, that might explain both issues.

I'll try that and see how it does.

 

On my 05 Xj8L I had a mass airflow sensor error throwing a code out of range off and on. It was annoying and I cleared it with my Bluetooth scanner which I keep connected. Eventually at autozone I got a replacement sensor a Duralast DL-3000 sensor which was installed in a few minutes. The car started up ran rough then settled down and over the next hour or so settled even more. It great by the next day though she started to stall at startup and also would require several tries to get it to stay running with throttle to 2k for about fifteen seconds then slowly leverage it down to idle or she would stall.

I switched the sensor back to my old which was semi faulty original sensor after cleaning it with some mass airflow cleaner and it started up fine.. Fast idled no issues then settled down and was smooth.

So my non professional answer would be check your mass airflow sensor.. Look at the live data for the sensor and see what it is doing via a graph format. Maybe this is the cause. If was for me.

I have read that I believe the Dorman sensor is the only sensor that seems to not cause any issues. I am not sure if this is true or not but would welcome the input from others.