All,


I'm currently trying to help a friend of mine with his 1991 NA 740. It is currently experiencing what he describes as a "bucking" issue.

The car in question is a '91 740 with M47 5-speed gearbox, 140k miles. He has owned this car since it was new.

The issue has been recurring for a year. What happens is this - when fully warmed up, as soon as you release the clutch to start in 1st gear, the car slightly shakes and sputters before the clutch engages. It happens when starting from stop signs or stoplights.

There was another issue that caused some problems last summer as well. On a cold start, the engine would hunt at idle - meaning, the tach would fluctuate between 800 and 1400 rpm, as if it was constantly revving. We diagnosed a dirty idle air control motor. We also cleaned out the throttle body as well.

Another thing accompanies the bucking issue. Normally, a healthy B230F will idle at around 850-900 rpm in Park or Neutral, depending on gearbox. My friend's car, when warmed up, idles at around 550-650 rpm. The "bucking," as I mentioned, takes place when starting out.

Welcome your thoughts and suggestions.