|Misfiring spark plugs
Recently, I had my car engine transplanted with a similar BMW engine (E32)
bought from some chop shop. After installing the engine, the car started to
I have changed the plugs. But they still misfire, and we found that the
sixth plug cable is not firing consistently. I changed to a new distributor
cap and rotor. It improved a bit.
But not satisfied with the performance, as it's still misfiring, I got a
new set of plug cables. But the performance is still bad. It could hardly
climb above 145km/hr.
When I rev the car in 'park', black smoke comes out. The spark coil was
changed about six months ago. Sparks from the coil (with the cable removed
from the distributor cap) are strong and consistent. But sparks coming out
of the cable to the spark plugs are weak. I have also got a new timing
sensor, but nothing seems to work.
I changed the old engine because it has a blown gasket. It needs daily
bleeding of the water system to remove build-up of excess air trapped in the
water system. Before the engine was removed, it could hit a top speed of
195km/h easily with good pick-up.
Answer : I think the problem lies in the distributor. Try to find
someone with an engine analyser so that you can see the behaviour of each
cylinder. You mention that you have replaced the rotor but I think you need
to recheck the fitting of the rotor to ensure that it is seated properly on
the shaft. Also the distributor cap has a notch to locate it in the correct
Sometimes if the cap is not fitted correctly, the engine will still start
but misfire as the spark cannot jump the gap between the rotor and the
contact inside the distributor for some cylinders. Your mechanic must also
be aware that if the distributor is not put in correctly, you will not be
able to adjust the advance properly and you may be run- ning with
insufficient advance. All in all, look at the distributor and if necessary,
send it to a specialist to check it out and confirm that the advance/retard
functions are working and that there is no excessive wear on the rotor