i have zen estilo 2007 model, it has cng kit installed, my car runs perfectly on cng but it knocks on petrol when under load like climbing slope or so. i used some filled some xtrapremium petrol in it, now knocking is lower but still present, i m also experiencing some power loss when in petrol but not in cng. will resetting ecu restore timing on petrol and stop knocking? what should i do now?