http://yedda.com/questions/Automatic_transmission_downshifting_273793803511515/?src=rss:qb:qbsAutomatic transmission not downshifting.en-ushttp://static1.yeddacdn.com/images/Logo132X46_rmt9c1d22d.jpghttp://yedda.com/questions/Automatic_transmission_downshifting_273793803511515/?src=rss:qb:qbsAutomatic transmission not downshifting.http://yedda.com/questions/Automatic_transmission_downshifting_273793803511515/?src=rss:qb:qbi<p>I have a 78 Chevy Malibu I just bought and have no history on the car. It does have a high-performance engine and thus has a low-intake-vacuum. The TH350 auto. transmission will not downshift when coming to a stop. What is the problem? Is it related to low intake vacuum/vacuum modulator or is it inside the transmission? Is the vacuum modulator only related to upshifts?</p>R JoynerR Joynermale62questionSat, 24 Oct 2009 02:33:51 GMThttp://yedda.com/questions/Automatic_transmission_downshifting_273793803511515/?src=rss:qb:qbihttp://yedda.com/questions/Automatic_transmission_downshifting_273793803511515/causes_problem_nbsp_replace_vacuum_504102273176294?src=rss:qb:qbi<p>there are several causes of your problem.  I would check to see that the vacuum hose to the modulator is connected and has the same vacuum reading as the manifold (with the engine idling).  next replace the vacuum modulator.  if that does not work, drain and flush the transmission.  be sure to replace as much of the fluid as possible.  not just 2 -4 quarts. if this doesn't work, many of the major transmission shops will diagnose the problem free.</p>olddadolddad66answer3.0Sat, 24 Oct 2009 23:30:14 GMThttp://yedda.com/questions/Automatic_transmission_downshifting_273793803511515/causes_problem_nbsp_replace_vacuum_504102273176294?src=rss:qb:qbihttp://yedda.com/questions/Automatic_transmission_downshifting_273793803511515/Joyner_u_manual_valve_boady_ur_gona_495310137653112?src=rss:qb:qbi<p>Joyner u have a manual valve boady ur gona have to shift it manually</p>RhondaRhonda49answer3.0Fri, 30 Oct 2009 01:51:49 GMThttp://yedda.com/questions/Automatic_transmission_downshifting_273793803511515/Joyner_u_manual_valve_boady_ur_gona_495310137653112?src=rss:qb:qbi