Hey peoples! New cca member here with a question that no mechanic seems to have an answer for... I have a 1984 318i with 154k original miles, i am the second owner bought it with 78k on it, it has always had a slight engine "cough" at freeway speeds and when accelerating especially in second and third gear. (manual trans) Ive had the fuel pump replaced, replaced all the fuel injectors, did a valve adjustment and timing chain tensioner, plugs, wires cap and rotor, adjusted the timing, but so far nothing seems to work! anyone had a similar prob? Any thoughts/help is appreciated! I am somewhat mechanically inclined and have a garage to work on the car but im not opposed to taking it to a mechanic either if someone has a resonable suggestion of something i havent tried yet... thanks Justin seattle
Our first thought is that you shouldn't be driving at freeway speeds in second gear! Beyond that I'd do a smoke test for vacuum leaks---I'd really expect it to be running lean. Cap, rotor and wires was a good idea---make sure the firing order is correct --- routing wires incorrectly can certainly cause backfires. Valve adjustment is critical---0.006-.008 cold and not too tight [using a go/no go feeler gauge is advised]. It is possible that you have internal engine problems---burnt valve, broken valve spring, rocker loose on the shaft, sticking valve---none of those are common. Check inside the distributor for smooth rotation of the shaft against the centrifugal weight springs, and complete return when the rotor is moved against the springs and then allowed to snap back. The shaft should not move sideways or back and forth loosely. Some fuel problems can cause lean running backfires, but that's unusual too. Or, it could be something else
