DME 7.8 DME 7.8 0 · Tester cables must not be connected to ground.

DME 7.8 DME 7.8 0 Figure: Warning! Tester cables must not be connected to ground. Note! If the engine does not start, or if the idling speed drops, replace tester cable connected to special tool. Perform system test for large lift Warning! Test is carried out while driving. Have a second person oper- ate the Porsche System Tester 2. System test for large lift means that faults are detected if a valve does not switch to large lift (fault type: above limit). Several cylinders may be stored as faulty, although only one valve on one cylinder is faulty. As a rule, only the cylinder bank with the faulty valve can be detected. Therefore in the case of a fault, the flat-base tappets of the inlet valves of the entire cylinder bank must be replaced. A faulty flat-base tappet can be detected because the oxygen sen- sor FR for this cylinder bank hardly changes the mixture at all given acceleration with wide-open throttle (FR at 1) and enriches the mix- ture in the opposite cylinder bank (FR > 1) see drawing below. Given a difference between FR1 and FR2 of more than 8 % during acceleration with wide-open throttle, a fault is certainly present. If the difference is less than 4 %, 1 valve may be faulty on both cylin- der banks. In this case, all flat-base tappets of the inlet valves must be replaced. 2470 P0306 0-49 page 7 Printed in Germany – 4, 2002 p0306