mpc8315e temperature related problem

I'm testing a MPC8315E board according to EN 50155.
In normal temperature (25 degree) , the board worked.
The board now have just CPU and NOR FLASH , test program is U-boot LED blinking.

1) During low temperature cooling test, CPU will not start up at -25 degrees after cooling for a while.
But If I power on 1.0V before 3.3V supply, then CPU can stat up and run.

2) During high temperature running test, CPU hang at about 50 degrees after running for a while.
Also, If I make hot air to CPU separately, it also can hang and stop running.
If i Make hot air to other parts separately, such as oscillators and NOR flash, CPU can run.

all parts are industrial grade which can work from -40 to 85.

what can be the possible reason for the problem?Thank you .

Have you actually measured the temperature on the CPU with temperature sensitive strips? What does the 1.0V power?
Frank

chuckey said:

Have you actually measured the temperature on the CPU with temperature sensitive strips? What does the 1.0V power?
Frank

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temperature is OK.
Development board from Freescale works without any problem.
Can it be related to EMC problem ?