When one of the primary ingredients of the gasoline engines operation, which is one of the greatest causes for the public seeking a professional mechanic is eliminated from the equation automobile mechanics are sometimes lost. There is no apparent tach signal, no way to quickly isolate a miss, no way to quickly check compression and no vacuum to test? Add to that the really poor offering of diesels from the Big 3, i.e., the Olds based debacle. I avoided them for the most part because they were so problematical and the automobiles they were in depreciated to scrap value quickly which made them unsellable for the cost of the repairs done. Mechanics must demand pre-payment for repairs on cars with no resale value. They became a cottage industry for back yard mechanics.