Announcement

Collapse
No announcement yet.

Unusual M42 running problem, slight missfire?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    Unusual M42 running problem, slight missfire?

    So my '91 E30 318iS runs wonderfully most of the time. But in one drive she has a stutter at the same bit of road every time I drive it!


    I can drive 30 miles from Aviemore down into Inverness no bother. On the way home there are a few big hills to climb at 70mph. About 2-3 miles after the final hill I'll always be sitting at 60mph due to average speed cameras. It's at this point the car stutters every trip and at no other time!



    It feels like she's not getting fuel and with the clutch out she'll stall. She bucks and jerks in a most unhappy manner. But if I change down to 4th gear and get the revs up the fault almost totally vanishes. Still happens with a full tank of fuel.


    I've tried new Motronic and fuel pump relays. Was thinking fuel pump but not sure.


    Stock apart from clearing up "the mess under the intake". She idles perfectly as a result. Certain there's no vacuum leak. Not lacking power.



    All help appreciated!
    My BMW site: www.unixnerd.demon.co.uk since 1996

    #2
    The A9 doesn't look too steep from what I can see on a map, so it would surprise me if it only happened on that drive, and several minutes after higher engine load has decreased.

    In any case, if you have a scanner that can read load/TPS signal/injector cycle/advance that would be the best way to see what is actually going on. For me the Schwaben scanner does those items, but cable length might be iffy to reach the cabin while driving.

    If that's not an option I'd try to record what engine RPM looks like during after the hilly section and try to replicate that same scenario at lower speeds in other gears to rule out elevation as a cause.

    Comment


      #3
      I've ordered a fuel pump, so we'll see. If it's not that then there's no harm in replacing a 30 year old one anyway!
      My BMW site: www.unixnerd.demon.co.uk since 1996

      Comment


        #4
        Just an update. New fuel pump and filter, good as gold now. All solved :-)
        My BMW site: www.unixnerd.demon.co.uk since 1996

        Comment

        Working...
        X