Bad main coil on dual spark 1150RTP

[DonW]

Jeez, it's just one thing after another. After trying to sort out an idle problem over the weekend, today my '04 R1150 RTP just crapped out at anything below about 3K RPM. I pulled both lower plug wires and it made no diff. So, haven't pulled the tank yet, but assume I have either 1) a bad connection to the coil, or 2) a bad coil.

 

I have a spare primary coil from my former '03 R1150RTP (single spark)that worked great when removed. Is it a plug and play replacement? If not, I have about a dozen BMW and after market dual output coils from my airhead renovations- will any coil with the right primary resistance work? The spare 1150 coil is about 1.0 ohms, and the airhead coils vary between 0.9 and 2.7 or so?

 

BTW, I don't run any radio stuff so do I need to worry about a "radio interferance coil"? The spare from the '03 rtp has a MASSIVE metal case around the actual coil, a big grounding braid, and fancy connectors for the output wires...

 

Boy it's good I like solving problems (with all of your help)!

 

Thanks,

 

Don

[Boffin]

Your oilhead coil will work fine, but you will need the non-screened leads to go with it.

 

Andy

[T__]

Don, first thing verify the coil on your bike now has actually failed.. Those coils are pretty hearty & seldom fail.. Check for power to the primary winding,, then check for wire continuity from the coil primary low side to the fueling computer..

 

Pop (known good) spark plugs in both plug wires then ground them both & crank the engine over (it can be any spark plug,, doesn’t have to be specifically for your bike) .. If you have spark then open the electrode gaps to 3/16” (use a 3/16” drill bit as a gap gauge) & try again.. If your coil will spark a snappy bluish spark across that 3/16” gap then I presume your problem isn’t the coil or the plug wires..

 

Remember that removing both plug wires at the same time hinders coil secondary grounding.. On those lost spark coil systems the spark plug on one side is the ground path for the other side so if BOTH plug wires are removed at once you are basically forcing the coil to arc internally to spark a spark plug..

 

It’s possible you just have fouled lower spark plugs & the coil is still OK..

 

If you need to change coils-- if you go with a shielded coil you will probably need the shielded plug wires to go with the coil as the wires attach to the coil differently.. Does your 04 have a shielded coil or just a standard coil & conventional plug wires?

 

I really don’t know about using a different type coil but you don’t want to use a lower resistance primary as that could damage the driver transistor in your fueling computer & the higher resistance coils are meant for a points type system using a condenser for primary wave dampening (might work but I can’t say that for sure)..

 

Twisty

 

[flars]

If you have 'lower plugs' you also have 'upper plugs'. I would tend to think you have a bad coil thingee on the top of your 'upper plugs'. That is what you need to pull off to see which side is not working.

The coil very seldom fails, but those other thingees fail all the time (relatively speaking).

[DonW]

I'm beginning to feel like a mechanical moron, but here's the latest. Yes, oh Guru Twisty, the primary coil seems to be fine. <> Good spark from both leads (and the stick coils too) with a 3/16" gapped plug. All plugs came out looking clean and maybe like the bike is running lean. Bike runs a bit better but still surges and is hesitant below 4K.

 

Per the other thread, I pulled the TB intake tubes, cleaned it all up, replaced the O-rings (mine old ones were OK, but I just could not get them small enough to pass the tubes over). Checked the timing (on "S" at idle and moves smoothly up from there). Going to ride today and see what happens...

 

Next step is to visit my buddy and do a full leak down test. I'll be back...

 

Don

[4wheeldog]

I am betting you have a bad stick coil........."They all do that".

 

Try running it with one side's stick coil removed from the plug in the motor grounded onto a spark plug.......When you disconnect the good one, it won't run.

[DonW]

I wish and hope that is true, cuz it's real easy to fix. But the bike runs with any of the four spark plugs off line, and runs better as soon as I return the spark. If I pull both bottom plug wires (now only running on the 2 stick coils), it still fires on both jugs, though not so well at low RPM.

 

Riding in to work today, with freshly cleaned TB butterflies, just checked spark plug and wires, and new fresh gas, it still ran crappy below 3K, and backfired down hills or on the freeway when I down-throttled.

 

As mentioned above, I'm going to get leak down test. I'm beginning to suspect a burnt valve...

 

Don

[T__]

Don, it sounds like you still have some issues with that bike.. Unless you can track down the bikes usage & service history about your only option is to keep checking & clearing the specific systems.. Might even be mechanical like coked up valve heads or plunging exhaust,, or worn cam issue..

 

I guess the next move is to test & track the TPS setting & the smooth tracking (if you already haven’t)

 

Probably the very first thing to do is re-set the Motronic.. To do that remove the #5 fuse (5th in from the outside) for about 3-5 minutes,, then reinstall the fuse,, then turn the ign switch on (do not start) then completely open & close the throttle twice (make sure the choke ‘fast idle’ is off).. That will re-set the TPS position learn & clear the long term fuel trim offsets..

 

If it still runs like crap below 3K do a TPS tracking & TPS base curb idle voltage check.. Digital voltmeter for the curb idle voltage check (needs to be under .4 volts -- probably around .365 to .385 volts (again choke off).. Then do a TPS smooth tracking test (you will need an old fashioned analog needle type voltmeter for this)..

 

I know you have done & tried a lot of things so if I mention it again & you have already done just disregard..

 

Try removing the CCP from the fuse box then ride it a few days, that should help the lower RPM runabilty but flatten the upper mid range & upper range..

 

Then replace the CCP & do the Motronic re-set (that I mentioned above),, then disconnect the 02 sensor & run it a day or two..

 

By doing one or the other of the above if you get a better below 3K runability it might point you towards a path to peruse to correct your problem..

 

Twisty

 

[DonW]

Thanks Twisty, I feel like I'm taking up too much bandwidth with this bike. But, here's a bit more info;

 

I do have a pretty good service history on the bike- CHP does EVERYTHING needed, and regular services. I contacted the dealer that did all the work, and got a history from about 50K on (109K now). Basically, no major work, no clutch ever replaced (unless before 50K), many stick coils, a drive shaft,several side stands, lots of lightbulbs, a few cop wiring things, a rear drive, fuel filters at specified intervals, etc.

 

I did reset the Motronic a last week, but will try it again. Not sure I did it right.

 

I pulled the o2 sensor again this morning, made no diff.

 

I will also remove the CCP- do I need to reset the Motronics at the same time? Or can I just pull it? I sort of want to do 'one thing at a time" so I can tell what makes the difference.

 

As I mentioned, I'm hoping to get a leakdown test later today, which seems like it will set some baselines for the pure mechanics of the engine.

 

Re the TPS tracking, I'll get geared up to do that, but need to study the process a bit and find an analog meter. I do have an entire spare right throttle body with TPS- maybe it would be a quick check to just bolt that on? That bike ('03 RTP) was running fine when this came off.

 

And once again- many thanks for everyone's help.

 

Don

[mbelectric]

Try the poor man's "burnt exhaust valve check" trick:

 

Place business card over tailpipe. Card should extend outward with exhaust flow. No sucking motion towards tailpipe.

 

MB>