968 Cabriolet L4-2990cc 3.0L DOHC (1993)
Idle Speed: Adjustments
Note: Idle and CO level adjustment is no longer possible on vehicles fitted with catalytic converter. When checking the idle CO level, the oxygen
sensor is not disconnected.
Check requirements
Perfect condition of the mechanical engine components. Loads must be turned off while checks are made. Perform checks as rapidly as possible to avoid
excessive heat buildup in the inlet ducts as this would give faulty CO level readings. Ambient temperature 15-35° C.
CO Test Connection
1. Connect commercially available exhaust gas adapter to test connector of catalytic converter.
2. Warm up engine to operating temperature. (Oil temperature 70-90° C), check with oil temperature tester (Special Tool 9122 and 9122/2).
3. Do not disconnect oxygen sensor connector. Connect CO level measuring instrument and separate tachometer according to manufacturer's
instructions.
CO check value
At idle ................................................................................................................................................................................................................ 0.4 - 1.2%
IDLE SPEED [1]
Manual .......................................................................................................................................................................................................... 840 ± 40 rpm
Automatic ..................................................................................................................................................................................................... 880 ± 40 rpm
[1] Idle speed is controlled by ECM and is not adjustable.