626 Turbo

Check voltage at EGI control unit terminal (1U) with ignition on, voltage should be less than 1.5 volts. Check ignition timing at idle. Disconnect knock sensor service connector (Blue/Yellow to Black/Yellow wire) near EGI control unit.

With engine at normal operating temperature, raise engine speed above 1650 RPM, lightly tap the surge tank and observe ignition timing. Timing should retard, if not check wiring or replace sensor with known good unit.

If timing retards, reconnect service connector and lightly tap surge tank again. Timing should not retard. If timing retards, replace knock control unit or repair wiring.