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EnergyPlus can simulate shorter time steps than defined in the 'TimeStep' object.

Timestep, 4;

There are zone time steps, defined above using the TimeStep object, and there are system time steps that can be shorter than this down to 1 minute intervals. When the system time step is shorter than the zone time step the output reported during the system time step are averaged over the zone time step interval. To see the output reports at the system time step enter a time step frequency of detailed in the Output:Variable object.

Output:Variable,*,Site Outdoor Air Drybulb Temperature,detailed;

Using this method should show either a 0, 1 or 2 in the output reports.

To lock down the system time step use the ConvergenceLimits object.

ConvergenceLimits,
  N1 , \field Minimum System Timestep
    \units minutes
    \type integer
    \note 0 sets the minimum to the zone timestep (ref: Timestep)
    \note 1 is normal (ratchet down to 1 minute)
    \note setting greater than zone timestep (in minutes) will effectively set to zone timestep
    \minimum 0
    \maximum 60
  N2 , \field Maximum HVAC Iterations
    \type integer
    \default 20
    \minimum 1
  N3 , \field Minimum Plant Iterations
    \note Controls the minimum number of plant system solver iterations within a single HVAC iteration
    \note Larger values will increase runtime but might improve solution accuracy for complicated plant systems
    \note Complex plants include: several interconnected loops, heat recovery, thermal load following generators, etc.
    \type integer
    \default 2
    \minimum 1
  N4 ; \field Maximum Plant Iterations
    \note Controls the maximum number of plant system solver iterations within a single HVAC iteration
    \note Smaller values might decrease runtime but could decrease solution accuracy for complicated plant systems
    \type integer
    \default 8
    \minimum 2

ConvergenceLimits,
  4;

or

ConvergenceLimits,
  0; (to match what you have entered in the TimeStep object)