My brother has an '83 528e w/ 117K miles on the clock. I had not seen the car in a couple months until this afteroon. He is experiencing a very rough running engine (idle surges around 700 RPM's) but also has a "gargle" sound below 2800 RPM's. It almost sounds like marbles on the bottom end of his engine. I drove the car 20 miles today and noticed that it is getting very poor gas mileage (went from above 1/4 tank down to the the occasional gas light on). Wondering if anyone has some troubleshooting advice for a this eta? Here is a rundown of the symptoms:
Poor gas mileage, sporadic idle, sounds like marbles in the engine at lower RPM's (injector noise), poor pickup, and the engine has a lot of side to side motion even under idle conditions.
Faulty Injector?, Vacuum Leak? Thanks in advance.