spark knock

My '92 Metro has developed a bad case of spark knock. I have set the ignition timing at 5 degrees BTDC with a jumper wire between the two terminals as per the underhood diagram. But, when the jumper wire is removed, the timing advances about 10 degrees more. Do Metros have a knock sensor that may have gone bad? This thing knocks even at the lightest load. Any help would be appreciated.
Thanks,

No, a metro doesn't have a knock sensor at all. They only used the knock sensor in the cultus GTi engine. at 15deg timing, no wonder it's knocking. For now, try to run midgrade or better fuel before you blow a piston up, or blow the headgasket. Does your dizzy have a mechanical vacuum advance on it?

make sure the egr system is not plugged and working properly.