well you cant expect this method of home chemistry to work 100% correctly, judging by the fact that you only used 4 pills it could be why you didnt experience pronounced effects. There are alot of variables doing CWE and i would only use it for low codeine dose pills around 10mg, as things like filter you use and how fine you crush up your pills etc. 1-2grams of paracetamol in a single dose is not dangerous its a very normal dose in a hospital setting although if this happens everyday you will start to see some liver damage.
Me personally I would just take 2-3 of the pills normally so that you get all of the chemical. You must realise what alot of people dont know that codeine isn't that great, it is what it is and nothing more. Opiates have a high and no higher high, other opiates like hydrocodone would be of more use recreationally to you, if the codeine still falls short. Personally i find weed codeine to potentiate each other as sometimes you have to find the codeine high, by deeply breathing or laying down on your back.
