Common problems in the Honda/Acura A4RA, B4RA and M4RA transmissions are harsh upshifts, downshifts and Forward engagements, while Reverse engagement is fine. These problems can be caused by a broken CPC (clutch pressure control) valve spring. The spring is located in the secondary valve body and is not available from Honda. Sonnax CPC valve spring 88894 has a wire diameter larger than the OE design. This significantly reduces the stress on the spring, preventing future breakage.