It is well known that most of the Alfv¿n waves generated in the solar wind by cometary ion pickup are propagating upstream in the solar wind reference frame. However, the magnitude of the small proportion propagating downstream is extremely important because it controls the amount of ion acceleration driven by the second order Fermi process. The velocity diffusion coefficient is approximately proportional to the intensity of the weaker component of the upstream or downstream propagating waves. In previous papers we developed a new technique to calculate the wave spectrum produced by pickup ions which successfully accounted for the total wave spectrum quantitatively. The theory also gives the spectrum of upstream and downstream waves separately. We set out to test the theory by obtaining the upstream and downstream proportions of the wave energy from the data. We have used analyses based on Els¿sser variables and the use of the Poynting vector and find that while the downstream proportion is small, it is much larger than expected, and its spectral shape is different from our theoretical prediction. The observations reveal that the spectrum of the cometary ion generated downstream waves is similar to that of the upstream waves, that is, a power law spectrum with a spectral index of -2 above the wavenumber corresponding to the cometary ion gyrofrequency. Since the weaker component is stronger than expected over a wide range of frequencies (and thus resonant velocities), the acceleration process will be enhanced and may be sufficient to explain the discrepancies between theory and observation which still exist. The mechanism responsible for the generation of the increased amount of downstream waves could be nonlinear induced scattering of the upstream waves by the solar wind protons. ¿ American Geophysical Union 1996