wide throttle open running issues

[jacktoth]

OK....I am frustrated on this one....

First let me say that I adjusted valves, balanced throttle body's, changed fuel filter, checked seals ,etc, etc....

When I open the throttles wide and accelerate I get hesitation and general rough, intermittent cough type running.....not the smooth torque acceleration up to 7K rpm as I had for the past 48K miles !!

It should be known that I don't have the issue if I accelerate lightly, i.e., not opening throttle full way, it's fine even to very hight rpm.

Any ideas would be appreciated !!!

[jcridge]

If you have a Dual Spark, Stick Coils and 4 spark plugs............

[owldaddy]

MIght try some Seafoam, could be dirty injectors.

[jacktoth]

used sea foam and techron several times....changed dual spark plugs in addition to things mentioned above....

[NoRRmad]

Stick coils?

[towerworker]

Sounds like a bad stick coil. Seems 04's and 05's are especially prone to this. My 04 did just what yours is doing. I replaced both primary coils (only one was bad) Problem solved.

Wayne

[boxermania]

Wayne is correct, early two spark plug R's are getting old and the stick coils deteriorate with exposure to heat. With the bike idling disconect one at a time and note the change in the running of the engine, no change = bad coil. Change in pairs and save the old "good" one for a rainy day.

Ocasionally the conector has been found at fault.....be careful removing the connector and check for broken wires.

[bimrluvr]

I had the same problem on mine and replaced my stick coils about 1 year ago. HUGE difference.
I'm not sure pulling one off at a time while the engine is idling is such a good idea. Couldn't that damage a good stick coil or other electrical doodads?
It would definitely be safer to turn the bike off, pull one out, then start 'er up. Listen for a bit. Shut 'er down. Repeat on the other side.

[Dr. Strangelove]

+1 on stick coils

just did it at 59k

The symptoms were vague at least for me. Everything I tried helped some-but not curative and I went through the litany you did. She was "reluctant" to wind out with WOT when she got to 4k and above; mileage went down about 8-10%, surging, p[reviously not an issue, was present in the typical ranges. I rode prob about 3k miles like that because I kept thinking it was something else, TB sync was what I thought. Gentleman's acceleration was almost just fine.

the test:

unplug the secondary plug, one at a time, on either side and try to start the bike. If it starts normally, that side's stick coil is ok. If it is worse ( or in my case would not start at all) that side's stick coil is the culprit. Replace both and happiness, joy and that sheet-eating grin when flogging her will return to your life.

Doesn't come cheap. Got mine from Chicago BMW at $97 each, maybe the cheapest price around. Took about 10 days to arrive.

Let us know how it turns out

John

[Dr. Strangelove]

Oh and PS

do the same test once you replace them to make sure they are both ok and you didn't get a dud

[iowabeakster]

Agreed with the primary stick coil hypothesis...and with replacing both.

but...

(I'm not trying to be difficult... just passing along information)

the test:

unplug the secondary plug, one at a time, on either side and try to start the bike. If it starts normally, that side's stick coil is ok. If it is worse ( or in my case would not start at all) that side's stick coil is the culprit.

Resident guru (aka Cyclerob) warns against this method. There is a potential of damaging the computer. Something about the high voltage electrons... that are output from the secondary coil... not having any path to ground... and possibly back-firing through the computer.

A safer test is to disconnect the primary plugs, one at a time, on a motor that is already fully warmed up. With a primary plug disconnected, the bike's idle should deteriorate (but it will still run on the secondary plug). Some people find this technique counter-intuitive. If the coil is good, disconnecting it will make it run worse. If the coil is bad, disconnecting it will NOT make it run worse. If the idle does not get worse...then the coil was already not working and the bike was just running on the secondary plug.

The easiest test is find a buddy with an oilhead that is running fine, and borrow his coils for a test ride.

[bimrluvr]

Thanks for clearing that up Iowabeakster.
I remembered that CycleRob had weighed in on this and that he'd mentioned some risk to the ecu, but couldn't remember which procedure he was recommending.

[Dr. Strangelove]

Agreed with the primary stick coil hypothesis...and with replacing both.

If the coil is bad, disconnecting it will NOT make it run worse. If the idle does not get worse...then the coil was already not working and the bike was just running on the secondary plug.

Didn't know or didn't remember the caveat from CR; but if that method is safer for the ecu, then I stand corrected. Thanks and don't burn your fingers.

[jacktoth]

Thanks everyone....seems like the consensus is stick coils...I am assuming is the same as ingnition coils ? .. Anyway, I am going to try replacing both (gulp expense !) and see what happens. But don't know why it would run at all on bad coil and why easy rev would be ok ?

Thanks to all.....

[towerworker]

The secondary plugs (under cylinders) are fired from another independent coil located under the tank. The bike will run on those plugs alone albeit poorly. I ran on one bad primary coil (stick coil--housed right inside the plug wire cap) for some time thinking something was wrong but it didn't run as poorly as I would have thought. Hence the secondary plugs were doing much of the work.

Wayne

[CycleRob]

It is never good to "open fire" a disconnected plug wire on any engine. The big spark energy generated has no place to go and therefore looks for the path of least resistance. With that secondary (sparkplug) circuit broken, that ~40,000 volt spark energy will try to jump to the ignition coil's primary (power) wire or the primary (ECU negative) wire, where it blasts right back into the ECU circuitry. Ford Motor Company says straight out that open firing their ignition system will damage the ignition computer. Duh! Most manufacturer's design in a measure of voltage spike protection for accidental plug wire disconnections, but it is still very risky to challenge your (expensive) system by open firing the secondary plug wire!!

The way to perform the secondary plug wire disconnected coil test is to connect another external sparkplug to the disconnected secondary wire and ensure the sparkplug metal case is continuously grounded to a bolt on the engine or cylinder head. That harmlessly shunts all the spark energy to ground. Another safer way is to just disconnect the coil's small primary (+) wire. The problem is that it is not very accessible on the OilHeads.

Misfire only on heavy throttle usually is bad plugs, weak spark energy or a clogged fuel filter.

.

[jacktoth]

Replace plugs and fuel filter.....so weak spark could be stick coils ?

[towerworker]

A bad stick coil will give you no spark. I would try Cyclerob's procedure on pulling the secondary plug and assuring the plug is grounded to the engine case so no potential damage is done to the ecu. If the engine dies when the secondary is pulled (with primary still connected) then the stick coil on that side is dead.


A side note: When I was trouble shooting my 04 I did not do as Cyclerob suggested by grounding that secondary plug. I simply pulled the secondary wire off the bottom plug (with the engine idling on the centerstand) The engine died and I then knew the stick coil on that side was dead. I did no damage to the bike but in retrospect I would not do that again and would follow Rob's advice. I think I simply got lucky.

[jacktoth]

OK...Problem Solved and Bike running again like a scolded KAT !...

Went to the BMW Dealer and asked if they could test the stick coils (I was having a hard time just buying them at $250 !). The Service Manager and mechanic said sure and just so happened to have two in the boxes (and correct new part #). He put them in and took for a test ride....fixed !

It appeared from their reactions that this is a common issue....and should be a recall !!

Anyway...thanks to all who steered me down the right path....

[eduardobelmonte]

Jacktoth says "why easy rev would be ok ?"

The reason is that when accelerating hard the amount of pressure in the cylinder is much higher and hence the spark needs higher voltage to jump..., if the coil is not strong or good enough then that voltage is not reached and you get a misfire. Also the sticks may be corroded or somehow cracked, and under hard acceleration electricity finds that to be an easier (lower voltage needed) path than to jump inside the cylinder.

If you go easy with the accelerator then presure in the cylinder will go up but not jump to a very high amount.

This same criteria applies for the spark plugs when they are old or faulty. When high pressure exists then they first start showing failure to produce spark.