Problems with analogReference(INTERNAL)

I am trying to perform two types of sensor readings, one test uses 5v and the other test uses the (1.1v)analogReference(INTERNAL) from the Arduino. My problem is once the Arduino moves past the code that uses the analogReference(INTERNAL) and analogReference(DEFAULT) is called the voltage does not go back to 5v. Any suggestions? Is there any way to convert the analog reading from using 5v to using 1.1v without using analogReference(INTERNAL).

Are you giving it a chance to settle in between changes? I don't think you can quickly bounce back & forth between them. Might have to take two readings after each change, and ignore the first one.

dcd012: I am trying to perform two types of sensor readings, one test uses 5v and the other test uses the (1.1v)analogReference(INTERNAL) from the Arduino. My problem is once the Arduino moves past the code that uses the analogReference(INTERNAL) and analogReference(DEFAULT) is called the voltage does not go back to 5v. Any suggestions? Is there any way to convert the analog reading from using 5v to using 1.1v without using analogReference(INTERNAL).

IIRC you have to do a call to analogRead() and throw away the result after each change to the analog refererence source to allow the ADC to recover from the change and for the AREF decoupling capacitor to charge to the new voltage - also you have to do the same on the first call to analogRead() after powering up.

Which voltage doesn't go back to 5V BTW? Are you measuring the voltage on AREF?