Buffer Problem with objects and double quotes

var object = {"hola":"mundo", "data":""}

var objectBuffer = new Buffer(JSON.stringify(object))
console.log(objectBuffer.length) // this should be 26 OK

var data0 = new Buffer('normal', 'utf-8')
console.log(data0.length) // this should be 6 OK

var data1 = new Buffer('"normal', 'utf-8') // Note extra double quote (it only happends with double quotes weird characters like ó work ok)
console.log(data1.length) // this should be 7 OK

object.data = data0.toString('utf-8', 0, 4)
console.log(object) // {hola:'mundo', data:'norm'} OK

var objectBuffer = new Buffer(JSON.stringify(object))
console.log(objectBuffer.length) // this should be 30 OK

object.data = data1.toString('utf-8', 0, 4)
console.log(object) // {hola:'mundo', data:'"norm'} OK

var objectBuffer = new Buffer(JSON.stringify(object))
console.log(objectBuffer.length) // this should be 30 NOT OK got 31 instead