Both Ignition Coils Gone at 35k miles

[bimrluvr]

The subject line says it all, pretty much. My bike was running lousy. I suspected the coil sticks based on symptoms I'd read about here on the forum. Brought it into my mechanic, but did not tell him what I suspected. Sure enough, he tested both coil sticks and they were both bad. Now that they've been replaced (and the 36k service has been done), my beauty is back to her old (new) self. Yay!

[boxermania]

This is another one of the engineering shortcomings of our bikes more prevalent now that the bikes are coming of age both in years and mileage.....geez, 35K miles.

I better keep my eye on Boxer's bike, with 78 K miles maybe the seat will turn into mush........

[R4R&R]

Were they both bad, or were they weak? Was the bike running at all? I had one go bad around 40k miles, but my two-spark '04 model was still running on the secondary plug. Due to the second plug, the cylinder with the bad coil was running a little rough, but still managed to get me home.

[CycleRob]

BOTH coils failed at about the same time? This happens way-waaay too much on the OilHeads!!

Near simultaneous failures can be 1 of 2 things:
--Severe engine overheating killed/degraded the coil's electronics.
--An errant damaging voltage from the Motronic or sparky sputter from a jumper cable, loose battery terminal or sloppy accessory power line installation.

If they failed on the same ride, I vote excess engine heat. These stick coils rarely/never fail on Japanese bikes that also use stick coils similar to BMW's. They rarely/never fail because they're safely running inside water cooled engines. With water cooling, there is no out of control excess engine heat possible as can frequently happen with the OilHead's no fan air/oil cooled design. Using stick coils is a bad design application for OilHeads that obviously should not have made it thru rigorous, responsible BETA testing. But it did. Guess why. Now, even after there is such an unusually high percentage of stick coil failures, the BMW brass still will not provide free/reduced cost out of warranty replacements or come up with a permanent solution. They know about it. Their parts department's re-orders show the infamous replacement numbers.

I'd still use the stick coils, but remotely mount them out-of-sight a few feet away and use a solid wire connecting secondary, just like the single sparks.

.

[bimrluvr]

Yes, both. I guess not actually dead, but in very poor condition. Bike was still running, but very poorly. I had been smelling unburned fuel for several weeks and had complained to the dealer about sudden die-outs at idle, whether warm or cold. They did not pick up the problem. When I took my bike to my shade-tree mechanic (he's also a fully certified BMW mechanic at a local shop during the week) and described the symptoms, he suspected right away and looked at the coils early on in his diagnosis. Proof is in the pudding, the bikes runs like new now...throttle response is back to full and gas mileage is back to normal, i.e. low 40s, up from low 30s before.

Now that I think of it, I discovered a loose battery connection a short while back...and I have a Centech panel installed (for a few years now). Possible that either of those may have contributed...I'll have to go back in and check the Centech connections...almost due for a new battery too.

Anyone know of any posted detailed decriptions on how to make remote-located coils? Or would anyone like to speculate on the details of how to do it?

[lionlady]

Discussion of interest on BMW Sport-Touring.net: http://bmwsporttouring.com/ubbthreads/u ... t=3&page=1

P

[sweatmark]

Has anyone converted dual-spark to single?

Seeing the conventional coil stashed under the tank of the Rockster, maybe this is another opportunity to simplify the uberladen R1150** bikes. Not like there is much performance to be lost.

[MotoDiva]

Heck, you did good; mine on my '04 R only lasted 22,500!! Could not figure out why she was running like a meat grinder instead of a bike! Took her in for a service and they discovered the prob. Those damn things weren't cheap either.

[CycleRob]

One more thing that will destroy the stick coils is an improperly tightened sparkplug, as in too loose. When it's too loose it does not transfer the fiery heat of combustion to the cylinderhead. When that happens, the plug gets really REALLY hot, transferring that excess heat to the stick coil plugged onto it. Where does that heat go? It all goes into the stick coil's circuitry, which cannot dump that heat anywhere but thru the rubber grommet where it contacts the valve cover. The verdict is dead stick coil(s), because someone was afraid of stripping the threads and unaware how tight is tight.

[sweatmark]

Anyone know if there's any timing delay between the stick coil plug and outer (conventional coil) plug? Or do the two plugs on each cylinder spark simultaneously?

[riceburner]

Were they both bad, or were they weak? Was the bike running at all? I had one go bad around 40k miles, but my two-spark '04 model was still running on the secondary plug. Due to the second plug, the cylinder with the bad coil was running a little rough, but still managed to get me home.

I've had it a few times.

I've funny feeling I might have it again.

Easy way to tell is to disconnect the secondary coils and see if she'll run. If not, you can swap the coil-sticks across and see if it's just one, or both.

They are too expensive though.

[owldaddy]

Anyone know of any posted detailed decriptions on how to make remote-located coils? Or would anyone like to speculate on the details of how to do it?

Back in the 70's I was riding Japanese machines, their ignition systems were poor at best, part of the problem was the weak coils (the points system sucked too). After reading an article in "Cycle" I changed the stock coils with automotive coils found at Kmart. They were inexpensive and HOT. One of the biggest advantages of using coils with more output was you could widen the plug gap. Automobiles at that time were running with gaps set about .035". The .028" gaps on a standard motorcycle was marginal, and misfires were not uncommon. These coils could fire a plug set at that gap easily. I haven't looked at the set up we have on the RR, but I'd be willing to bet that a swap could be done to those type of coils. They are reliable and cheap to replace if that should become necessary. Perhaps if I have trouble with my stick coils I might look into doing that to this bike. My RD 400 loved the change.
Don

[sweatmark]

So what are we talking about here - $100-120 per stick coil?

Is this yet another oilhead achilles heel?

Hmm... I'm getting that post-warranty bike hacking urge again. Look for another DIY thread over in Rockster section over the next month.