Ducati Sporting Club UK > Model Specific - Discussion, Technical Problems and Help > 998 / 996 / 916 / 748 > Confused - ignition coil resistance

[jbeez_yuall]

Is the haynes manual correct?

It states primary coil 495-606 Ohms

Secondary 6.66 - 8.14 K Ohms.

I have three coils here for 748, all measuring ~1.0 Ohms primary and 3.2K Ohms secondary

Are they all toast or is the haynes manual wrong?

If there all toast this is good, but I have a sneaky suspicion a new one is going to turn out to give similar readings.

Trying to solve an intermittant misfire, typically occurs under load only, removing nology leads, fitting old leads and closing up plug gaps solved it for three days, only to have it return with vengeance, so ignition seems likely, possibly killed the coils with the nology wires.

[dunlop0_1]

Possible pick up sensor breaking down or the connector plug has had water in and corroded?
Andy pike had a similar problem which turned out to be a cracked fuse.
Also change the yellow relay and the two relay's under the seat.

[jbeez_yuall]

I'v also downloaded a ducati workshop manual and the haynes manual is infact incorrect.

Primary coil resistance should be 0.495-0.606 Ohms

Secondary 6660-8140 Ohms.

Which makes much more sense, so just my secondary windings are a bit low, but not necessarily the problem.

Pick up sensor sounds a good one, The plug is all nice and clean, but could well be worth getting another sensor.

Will change the relays too.

I'v got her in bits at the moment to change the cam pulley bearings, check valve clearances after I adjusted them last year and sort this annoying problem, ready for some new rubber and a summers fun, taking her to le-man for the 24 hr, so need her to be reliable soon!

[nelly]

Check the air gap on the pick up sensor. Seen a few that return good resistance values but the gap has been too wide. Aim for the tighter end of the install values. About 0.6mm

[jbeez_yuall]

I will, but why should it all of a suden become a problem? Been running well with the gap its at for years.

[dunlop0_1]

Originally Posted by jbeez_yuall

I will, but why should it all of a suden become a problem? Been running well with the gap its at for years.

If the sensor is starting to break down with age then it can't maintain sensing the original air gap of say 0.6mm. So effectively it's like the gap has widened so setting the gap to say 0.4mm may or may not help, but has to at least be worth checking.