diff --git a/src/Control/Session.php b/src/Control/Session.php
index 917fea78c..e2591d2c5 100644
--- a/src/Control/Session.php
+++ b/src/Control/Session.php
@@ -300,55 +300,46 @@ class Session
 
         // If the session cookie is already set, then the session can be read even if headers_sent() = true
         // This helps with edge-case such as debugging.
-        if (!session_id() && (!headers_sent() || !empty($_COOKIE[ini_get('session.name')]))) {
+        $data = [];
+        if (!session_id() && (!headers_sent() || $this->requestContainsSessionId($request))) {
             if (!headers_sent()) {
-                session_set_cookie_params($timeout, $path, $domain ?: null, $secure, true);
+                session_set_cookie_params($timeout ?: 0, $path, $domain ?: null, $secure, true);
 
                 $limiter = $this->config()->get('sessionCacheLimiter');
                 if (isset($limiter)) {
                     session_cache_limiter($limiter);
                 }
 
-            // If headers are sent then we can't have a session_cache_limiter otherwise we'll get a warning
+                // Allow storing the session in a non standard location
+                if ($session_path) {
+                    session_save_path($session_path);
+                }
+
+                // If we want a secure cookie for HTTPS, use a separate session name. This lets us have a
+                // separate (less secure) session for non-HTTPS requests
+                // if headers_sent() is true then it's best to throw the resulting error rather than risk
+                // a security hole.
+                if ($secure) {
+                    session_name($this->config()->get('cookie_name_secure'));
+                }
+
+                session_start();
             } else {
+                // If headers are sent then we can't have a session_cache_limiter otherwise we'll get a warning
                 session_cache_limiter(null);
             }
 
-            // Allow storing the session in a non standard location
-            if ($session_path) {
-                session_save_path($session_path);
-            }
-
-            // If we want a secure cookie for HTTPS, use a seperate session name. This lets us have a
-            // seperate (less secure) session for non-HTTPS requests. Note that if this causes problems
-            // if headers_sent() is true then it's best to throw the resulting error rather than risk
-            // a security hole.
-            if ($secure) {
-                session_name($this->config()->get('cookie_name_secure'));
-            }
-
-            session_start();
-
             if (isset($_SESSION)) {
                 // Initialise data from session store if present
                 $data = $_SESSION;
+
                 // Merge in existing in-memory data, taking priority over session store data
                 $this->recursivelyApply((array)$this->data, $data);
-            } else {
-                // Use in-memory data if the session is lazy started
-                $data = $this->data;
             }
-            $this->data = $data ?: [];
-        } else {
-            $this->data = [];
         }
 
-        // Modify the timeout behaviour so it's the *inactive* time before the session expires.
-        // By default it's the total session lifetime
-        if ($timeout && !headers_sent()) {
-            Cookie::set(session_name(), session_id(), $timeout/86400, $path, $domain ? $domain
-                : null, $secure, true);
-        }
+        // Save any modified session data back to the session store if present, otherwise initialise it to an array.
+        $this->data = $data;
 
         $this->started = true;
     }
@@ -438,7 +429,7 @@ class Session
         }
 
         $var[] = $val;
-        $diffVar[sizeof($var)-1] = $val;
+        $diffVar[sizeof($var) - 1] = $val;
     }
 
     /**