AJAX - problema al enviar variable por ajax (imagen y el id al actualizar)

<div class="col-md-5 h-100" align="center">

    <div id="load_img">

        <img class="img-responsive" src="<?php echo $row['imagen'];?>" alt="Logo">

    </div>

    <br>

        <div class="row">

            <div class="col-md-6" >

                <div class="form-group">

                    <input class='filestyle' data-buttonText="Logo" type="file" name="imagefile" id="imagefile" onchange="upload_image('<?php echo  $row['id_producto'];?>');">

                </div>

            </div>

        </div>

</div>

function upload_image(id){

    var inputFileImage = document.getElementById("imagefile");

    var file = inputFileImage.files[0];

    if( (typeof file === "object") && (file !== null) )

    {

        $("#load_img").text('Cargando...');

        var data = new FormData();

        data.append('imagefile',file);

        $.ajax({

            url: "ajax/update_img.php",

            type: "POST",

            data:"id="+id, data,

            contentType: false,

            cache: false,

            processData:false,

            success: function(data)

            {

                $("#load_img").html(data);

            }

        });

    }

}

if (isset($_FILES["imagefile"])){

    $id_p=$_POST["id"];

    $target_dir="../vendor/img/products/";

    $image_name = time()."_".basename($_FILES["imagefile"]["name"]);

    $target_file = $target_dir . $image_name;

    $imageFileType = pathinfo($target_file,PATHINFO_EXTENSION);

    $imageFileZise=$_FILES["imagefile"]["size"];

/* Fin Validacion*/

    if ($imageFileZise>0){

        move_uploaded_file($_FILES["imagefile"]["tmp_name"], $target_file);

        $logo_update="imagen='vendor/img/products/$image_name' ";

    }	else { $logo_update="";}

        $sql = "UPDATE products SET $logo_update WHERE id_producto='".$id_p."' ";

        $query_new_insert = mysqli_query($con,$sql);