Yup this is it!
Sometimes I had it all day long while driving on straight flat roads.
Then I decide to go service centre made appointment and suddenly on that day it went empty.. lol betul!!!

Mind blown 🤯 totally

Meanwhile thanks for the reply..
Yet I still assumes that 20% of iriz total production had this issue.. Which is unacceptably fail.. in quality control.. shame on Proton manufacturer.

How sure r u that the sound is from engine knocking? Have u tried revving the engine while being stationary, to hear if there's any pinging noise?

I used to having this weird metallic pinging noise & i thought it was coming from the engine. Until 1 fine day, while trying to dampen some dashboard rattling sound, I removed the glove box & run my hand in it gently tapping around & found that 2 screws connecting between 2 parts of metallic sheets are not secured with nuts. Once i secured both screws with nuts, the metallic pinging noise is gone. That 2 sheets of metal parts are around the left side of the aircond blower. U can try to tap ur hand around that area.

If the noise is really caused by engine knocking, try a bottle or 2 of Techron Concentrate Plus from Caltex. Pour it into ur fuel tank when u refuel. It helps to remove carbon deposits from the fuel system & some of the engine parts. Caltex even produced this as OEM for BMW to clean carbon deposits. Same bottle design, same content, but relabeled it with BMW label. It costs RM46 per bottle. Nvr tried, nvr know...

Bro, it's not EO additive. It's fuel addictive with PEA detergent that will get rid of carbon deposits. Every fuel on the market has additive added, like detergents, friction modifier, anticorrosive agents. The industry branded it like, shell fuelsave, shell v-power racing, Petronas primax prodrive, caltex w/ techron, bhp infiniti. These additives r one of the many factors that set each different fuel brand apart. Techron is already available in Caltex fuel, except that this Techron Concentrate Plus is a more concentrated form of it. It won't affect the viscosity of your EO.

Bro, it's not EO additive. It's fuel addictive with PEA detergent that will get rid of carbon deposits. Every fuel on the market has additive added, like detergents, friction modifier, anticorrosive agents. The industry branded it like, shell fuelsave, shell v-power racing, Petronas primax prodrive, caltex w/ techron, bhp infiniti. These additives r one of the many factors that set each different fuel brand apart. Techron is already available in Caltex fuel, except that this Techron Concentrate Plus is a more concentrated form of it. It won't affect the viscosity of your EO.

I usually pour a bottle of it everytime after 10k service interval. All fuel already hv detergent in it. It's just that this product is more concentrated & i added it every 10k to serve as a preventive maintenance to clean existing carbon deposits & minimize any future build-up.

U might also wanna consider revving ur engine hard once in a while. It is a method which they coined it as "Italian tuneup" & it's what the technicians in Ferrari do after each service maintenance to rid carbons. The key is to rev ur engine hard & get it hot enough to naturally burn off those carbons.

Ur tranny is MT or CVT?