Ignition Circuit -B- Problems
in 912 / 914 Technical Questions
8 years ago
Good afternoon everybody
Maybe this problem was already discussed before but I couldn ´t find a topic.
Engine: 912UL 80hp, New spark plugs, Compression ok, etc.
Phenomenon:
During Run Up on ground Ignition circuit -B- delivers a very rough engine run below ~3000rpm.
Above ~3000rpm Circuit -B- is running fine (rpm drop at 3800 approx 150rpm)
Ignition Circuit -A- is always good.
In Flight Circuit -B- shows a fall back into it´s bad behavior on ground during all rpm-ranges
(Very rough engine run with a loss of >500rpm)
First I suspected Circuit -B- running on 3 sparks only but this was not confirmed.
(I pulled all -B- sparks one by one and grounded the plug concerned with a dummy-spark-plug.
Result: the engine run was even rougher. I even tested all -B- sparks with a colortune tool)
Next investigation step was to swap the trigger-coil plugs in order to find out that the trouble
moved to the -A- Circuit. Therefore I assume the electronic modules and coils to be ok.
Hence I suspect the -B- sparks to be too weak or their ignition timing slipped behind -A- ??
Then i grabed my old multimeter and tested the trigger-coils.
The resistance on all 4 ´channels´ is fine (4x 230 Ohm)
Next step will be to verify the small gap between the rotating part and the trigger coils
(0,3mm approx)
Any idea somebody in this community?
brgds
Gerhard
Maybe this problem was already discussed before but I couldn ´t find a topic.
Engine: 912UL 80hp, New spark plugs, Compression ok, etc.
Phenomenon:
During Run Up on ground Ignition circuit -B- delivers a very rough engine run below ~3000rpm.
Above ~3000rpm Circuit -B- is running fine (rpm drop at 3800 approx 150rpm)
Ignition Circuit -A- is always good.
In Flight Circuit -B- shows a fall back into it´s bad behavior on ground during all rpm-ranges
(Very rough engine run with a loss of >500rpm)
First I suspected Circuit -B- running on 3 sparks only but this was not confirmed.
(I pulled all -B- sparks one by one and grounded the plug concerned with a dummy-spark-plug.
Result: the engine run was even rougher. I even tested all -B- sparks with a colortune tool)
Next investigation step was to swap the trigger-coil plugs in order to find out that the trouble
moved to the -A- Circuit. Therefore I assume the electronic modules and coils to be ok.
Hence I suspect the -B- sparks to be too weak or their ignition timing slipped behind -A- ??
Then i grabed my old multimeter and tested the trigger-coils.
The resistance on all 4 ´channels´ is fine (4x 230 Ohm)
Next step will be to verify the small gap between the rotating part and the trigger coils
(0,3mm approx)
Any idea somebody in this community?
brgds
Gerhard
