Update of the Electron Cloud Simulations for DAFNE

A strong horizontal instability, limiting the positron current at I {approx} 500mA, has been observed at DAFNE since the installation of the FINUDA detector in 2003. Experiments and simulations seem to provide evidence that the electron cloud build-up in the wigglers and bending magnets of the DAFNE positron ring induces coupled bunch instability with features compatible with observations. Recently the installation of a new horizontal feedback system allowed to control the instability for value of the positron current as high as possible (I {approx} 1000mA). To better understand the electron cloud effects and possibly to find a remedy, a detailed simulation study is undergoing. In this communication we present recent simulation results relative to the single bunch instability induced by an electron cloud interacting with the beam.