90 si stock engine light knocking noise only during hot weather and after hard driving and cel comes on when I check for codes there are none. Engine smokes a little bit under wot but seems to run strong still. it also sometimes idles below 600 then goes back up to normal. I'm not driving the car anymore but I would like to know if its a big problem or timing related belt seems to be more loose the usuall and I was thinking it could have jumped timing. I don't know if this is even possible. Thanks