Engine Stuttering Problems

[rayncc]

Hi all,Was driving my E30 yesterday when suddenly the engine encountered stuttering problem with following symptoms :-1. Engine will simply dies off in free gear. Can't even idle2. Engine extremely difficult to rev; feels very heavy3. In order to drive car, have to use low gears (i.e. 1, 2 or at most 3 depending on speed) to literally drag the car to move because the revs refuse to climb hence totally no power. 4. When stomp the pedal to rev the engine, plenty of black smoke as if the engine running very richHowever after constant and forceful reving of the engine, the problem disappears. Upon checking, the flap inside the AFM appears clean and have good clearance in its movement except the throttle body which has fresh lubes which show signs of overflow of engine oil.Even now without the stuttering problems, i feels that the engine sometimes experience 'flat spot'....for example when driving in 5th gear at 3k rpm, when step on the pedal the engine sorts of hesitates a while before responding. Normally the car will just pick up speed instantly.Can some sifu out there care to advise what could the problem be? Thanks.....

 

[dpointt]

no problem, just need an overhaul!!! kekeke...

 

[bmw4eva]

Sounds like your airflow sensor is bad.Your engine hesitates because its either running too lean or too rich.On those old E30, you can adjust the flapper door tension inside the airflow sensor(located inside a black cover on the side of the airflow sensor).The tighter the spring, the leaner the mixture.To richen the mixture,losen the tension a bit.

My old E32 had this problem before.Over time, the tension on the flapper door got lose and as a result,was burning too rich.It always stalled everytime i put it in Drive or Reverse.All I did was tighten the spring on the side of the airflow sensor to where to was tight enough and it cured the problem.It took an entire day for me to do this on my own, but definitely easy for a DIYer.

 

[rayncc]

Hopefully its a one-off problem. Sent to Heritage Services for service & tuning today. So far car working fine and hopefully will stay the same...