|
As I drove my 1992 740 turbo today, crusing at 70 mph, the tach was at about 2800 rpm which is where it runs for that speed. To my surprise I saw it jump up to 3500. I did not increase the gas petal nor did the car's speed change. (the tach change was a false indication) when I let off the gas a litte the tach fell to a reasonable 2500 and then when I went back to 70 mph it returned to 2800 rpm. It did this twice more then behaved it self. When the tach jumped up to 3500 from 2800 the engine ran smooth. What drives the tach? I assumed it was the engine crank sensor. Any ideas anyone. Thanks.
Mike Kaz
|