In order to extract the full measure of performance and economy from your engine it is essential; that it is properly tuned at regular intervals. A regular tune-up will keep your car's engine running smoothly and can prevent the annoying breakdowns and poor performance associated with an untuned engine.
Except for the 633CSi and 733i, all models built before 1980 have a conventional breaker point ignition system. All models built after 1980 utilize a pointless, electronic ignition system.
A complete tune-up should be performed on early models every 12 months or 12,000 miles (19,000 km), whichever comes first. On later models, the interval is 12 months or 15,000 (24,000 km), whichever comes first.
This interval should be halved if the car is operated under severe conditions such as trailer towing, prolonged idling, start-and-stop driving, or if starting or running problems are noticed. It is assumed that the routine maintenance described in Routine Maintenance has been kept up, as this will have a decided effect on the results of a tune-up. All of the applicable steps of a tune-up should be followed in order, as the result is a cumulative one.
If the specifications on the underhood tune-up sticker in the engine compartment of your car disagree with the Tune-Up Specifications chart in this section, the figures on the sticker must be used. The sticker often reflects changes made during the production run.