{"id":481,"date":"2017-08-24T16:03:59","date_gmt":"2017-08-24T16:03:59","guid":{"rendered":"http:\/\/autotechdiagnostics.com\/?p=481"},"modified":"2023-05-26T13:40:26","modified_gmt":"2023-05-26T13:40:26","slug":"sold-gasoline-engine-vacuum-specifications-and-testing-diagnosing","status":"publish","type":"post","link":"https:\/\/autotechdiagnostics.com\/?p=481","title":{"rendered":"Gasoline Engine Vacuum Specifications and Testing (diagnosing)"},"content":{"rendered":"

Use the directions and read the safety warnings that came with your vacuum gauge.<\/p>\n

    \nWhen testing, connect vacuum gauge to a vacuum port on intake manifold. You want the reading to come after the throttle plate. If you do not have to drive the vehicle, the brake booster vacuum hose is a good place to tap in. As you will get good volume. It is important not to drive the vehicle with a gauge tied into brake booster vacuum hose.<\/ol>\n

    Engine Vacuum Specifications<\/font><\/strong><\/p>\n

  1. Engine cranking, not starting: 2″ – 5″<\/strong><\/li>\n
  2. Engine running at idle, warm: 18″ – 21″<\/strong><\/li>\n
  3. Wide open throttle: 0″ – 3″<\/strong><\/li>\n
  4. Engine deceleration: 21″ – 24″<\/strong><\/li>\n

    Engine Vacuum – How to Test<\/font><\/strong>
    \nSnap throttle\tJumps to 2″ then on decel moves to 25″\tHealthy
    \nSnap throttle\tJumps to 1″ then on decel moves to 22″\tFair but worn
    \nIdle\t8″ or less\tVacuum leak, loose intake manifold
    \nIdle\tFluctuated between 14″ – 19″\tWorn valve guides or head gasket blown between 2 cylinders
    \nIdle\tReading drops from normal\tBurnt valve, valve stuck open, misfiring spark plug
    \nIdle\t8″ – 14″\tValve timing incorrect or large camshaft overlap
    \nIdle\t14″ – 16″\t Ignition timing wrong
    \nIdle\t Moves between 12″ – 16″\tIdle mixture incorrect
    \nSlow engine speed rise\tNeedle falls then rises suddenly\tBlocked exhaustWeak valve springs
    \n3000 rpm\tNeedle fluctuates and worsens with higher rpm\tWeak valve springs<\/p>\n","protected":false},"excerpt":{"rendered":"

    Use the directions and read the safety warnings that came with your vacuum gauge. When testing, connect vacuum gauge to a vacuum port on intake manifold. You want the reading to come after the throttle plate. If you do not … Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[7],"tags":[234,233,231,232,215,236,237,238,235],"_links":{"self":[{"href":"https:\/\/autotechdiagnostics.com\/index.php?rest_route=\/wp\/v2\/posts\/481"}],"collection":[{"href":"https:\/\/autotechdiagnostics.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/autotechdiagnostics.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/autotechdiagnostics.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/autotechdiagnostics.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=481"}],"version-history":[{"count":12,"href":"https:\/\/autotechdiagnostics.com\/index.php?rest_route=\/wp\/v2\/posts\/481\/revisions"}],"predecessor-version":[{"id":716,"href":"https:\/\/autotechdiagnostics.com\/index.php?rest_route=\/wp\/v2\/posts\/481\/revisions\/716"}],"wp:attachment":[{"href":"https:\/\/autotechdiagnostics.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=481"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/autotechdiagnostics.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=481"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/autotechdiagnostics.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=481"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}