Hi, My Citroen AX 1996 1.0 liter engine. When I accelerate & shift to 3rd gear I can hear a pinging like knock sound. What would be the problem? They advise me to switch to 95octane petrol since I'm using a 91octane. Please advise
yes, switch, that will help. I would also do a complete tune up. best of luck.
Agreed, and if there is a knock sensor in this engine, you might want to have it checked for operation, as most newer vehicles can compensate for some knock through the use of the knock sensor which adjusts timing if spark knock is detected.