On the V8 (D-Jetronic) cars, bidders treat a cold-start video as essential because the startup sequence reveals the health of the injection and timing components. A common, benign symptom is a hunting cold idle caused by a sticking auxiliary air valve, cleanable rather than catastrophic. …
D-Jetronic, cold-start diagnostics and the auxiliary air valve
Mercedes-Benz 250S-300SEL 6.3 (W108/W109) · mechanical