/**
 * Customize Event Query using Post Meta
 *
 * @author Bill Erickson
 * @link http://www.billerickson.net/customize-the-wordpress-query/
 * @param object $query data
 *
 */
function be_event_query( $query ) {

    if( $query->is_main_query() && !$query->is_feed() && !is_admin() && $query->is_post_type_archive( 'e4gf_events' ) ) {
        $meta_query = array(
            array(
                'key' => '_e4gf_event_meta_date',
                'value' => time(),
                'compare' => '>'
            )
        );
        $query->set( 'meta_query', $meta_query );
        $query->set( 'orderby', 'meta_value_num' );
        $query->set( 'meta_key', '_e4gf_event_meta_date' );
        $query->set( 'order', 'ASC' );
        // $query->set( 'posts_per_page', '4' );
    }

}

add_action( 'pre_get_posts', 'be_event_query' );