A direct implicit ion polarization gyrokinetic full f particle-in-cell approach is implemented with kinetic electrons in global tokamak transport simulations. The method is applicable for calculations of rapid transients and steep gradients in the plasma, which is made feasible by recording the charge density change by the ion polarization drift together with the particle advancing. The code has been successfully validated against the linear and nonlinear predictions of the unstable mode growth rates and frequencies and their turbulent saturation level. A first global validation of the neoclassical radial electric field in the presence of turbulence for a heated collisional tokamak plasma is obtained. The neoclassical radial electric field together with the related geodesic acoustic mode oscillations is found to regulate the turbulence and heat and particle diffusion levels in a large aspect ratio tokamak at low plasma current.