Rough idle, wants to stall

[priapismic]

The particulars: early release 2004 R bought new in March of '03. I am the original owner. 58k miles. I do most of my own services - valve adj's., fluids & filters, plugs, etc. Everything is fresh and current except for a TB sync. Fuel filter was replaced earlier this year by a BMW shop (pulling the tank off is one thing I'm not comfortable with).

The symptoms: The R is running like snot thru a baby, but isn't idling right - sometimes it stumbles and tries to die. Sometimes it dies as I coast to a stop. At a traffic light I have to keep a little throttle fed in so it won't hiccup and stall. I upped the idle last week but it's still touchy. Other than a little stumbling (not really surging) at low rpm/low throttle the bike runs out to redline just fine - no hesitation at all. I gonna pull the plugs and check the air filter (K&N that's been in for a couple of years that I pull and clean annually) and all that, but the poor thing hasn't had a TB sync in prolly 2 years. Couldn't hurt, eh?

Whatta you guys recommend?

[iowabeakster]

Give the coils on the primary spark plugs a check, while your at it.

[boxermania]

+1 with the coils....as it is a common occurrence. Gradual decay due to heat exposure is the culprit. Good luck.

[priapismic]

Give the coils on the primary spark plugs a check, while your at it.

The services I do are the full extent of my mechanical expertise, so I'm kind of a dummy about some things. Just where are the coils located, and how does one go about testing them? And if the coil(s) are faulty, wouldn't that show up in rough or irregular running? Remember, the bike runs like a bat outta Heck under full throttle - no complaints there at all.

Thanks for the tip!

[priapismic]

An update: I pulled the plugs, all look fine and are gapped correctly. I also pulled the #5 fuse and reset the Motronic. I took a short ride today, and after running enough to get everything thoroughly warmed up, I adjusted the idle speed up on both sides just a bit. Still a bit of stumle at idle - rpm's bounce around between approximately 1100 rpm to 1400, sometimes dropping to around 1000. It was that drop that previously had me concerned that it might stall at a stop. Now that the idle is up it stills kinda hiccups, but I don't think it will drop rpm's enough to die. Still runs like stink at WOT, though, it just isn't smooth at idle. Throttle position sensor, anyone?

[boxermania]

TPS is the unlikely culprit as it is a resistance and a wiper and if the resistance wire would have been broken the bike would not have run at high rpms...or so I think.

If you have the 4 plug version it is possibly one or both of the in the head coils, based on your mileage I'm almost certain that is the problem. I don't know what is the coil resistance to be measured. However, CycleRob might know, if not call www.beemerboneyard.com and ask them how to check them. They also sell the parts, at less cost than the dealer.

[zeke]

Check your vacuum tubes and fuel lines. I had/have a similar problem:
viewtopic.php?f=2&t=15702&hilit=zeke

I noticed it shortly after the tank was removed as well. It was your description of the idle being erratic from 1000-1600 RPM. I am planning on removing the tank and replacing the QDs with SS to see if this resolves the problem.

[Rockosmith]

If you have a 'two spark' engine, it sounds like the 'coil sticks'. This is an ignition coil built into the plug cap on the primary plugs. My '04 two sparker did almost exactly the same thing. Two new coils later, all is fine. You will probably have to re-adjust your idle speed down if you cranked it up.

[Beemeridian]

11

[towerworker]

Check your vacuum tubes and fuel lines. I had/have a similar problem:
viewtopic.php?f=2&t=15702&hilit=zeke

I noticed it shortly after the tank was removed as well. It was your description of the idle being erratic from 1000-1600 RPM. I am planning on removing the tank and replacing the QDs with SS to see if this resolves the problem.

I didn't know these things had vacuum tubes! Thought they were all transistors!

Now I wish I hadn't thrown away my tube tester. Darn

[Beemeridian]

11

[priapismic]

"Stick coils", eh? Alright, then, a couple questions:

- just where exactly are these buggers?
- can they be tested?
- are they easily removed and replaced?
- if the coils are bad, wouldn't that affect high speed running also? Remember, the bike runs like a hound dog after a jackrabbit under full throttle - no missing, no hesitation, nothing.
-anybody got a part number so I can check with Beemer Boneyard or Chicago BMW?

Thanks for all the tips so far.

[Sunbeemer]

Wouldn't hurt to add a couple ounces of Sea Foam to a full tank of gas - it's worked for me.
Don't know much about stick coils since I don't have any, and I always thought they were on the secondary plugs?

[duckdave]

Pria,
Your symptoms mirror mine somewhat, I think. Would you agree with, "idling roughly, rough warm-up, lower than normal rpm's at idle, need to keep idle + switched in the + position until it warms up good..." I rarely run the snot out of it, but it seems fine on the highway (merging, getting the heck out of there) and I've enjoyed the sweepers and twisties recently without regret. Besides the above, the only other description I might add is "sluggish" in the around-town sense—the slightly troublesome performance problems seem to be predominate in the riding I encounter from home to work and back (about 8 miles, sometimes I don't get out of 3rd gear). On the highway (anytime there is no one ahead of me), no problems.

I've been wondering stick coils for a while. And wondering exactly how to test them.

There seems to be a bit of debate about grounding versus not grounding the pulled plug (whatever that means)?. And some details are left out about the specifics about testing procedures.

I'd love a "step-by-step" on this potential problem.

[iowabeakster]

just where exactly are these buggers?

When you change the spark plugs, you use a (crappy) plastic tool to pull a black shaft out of the hole that connects the ignition wire to the spark plug. That black shaft is the stick coil.

are they easily removed and replaced?

Yep. You pulled them out with every spark plug change and valve adjustment with that crappy plastic tool.

can they be tested?

Yes. You can test the resistance with a multi-meter. Sorry, I don't know what the measurement should be though. Anybody Know?

(In my foggy memory) I remember somebody testing their coils and it showed the right resistance but it still didn't work right. So an easy way is to find a friend with a smooth running bike and swap them, if your bike runs smooth you found your culprit. It might be only one coil at this time, remember that you other one is just as old. Some have found visible damage to the exterior of the coil and cracked plastic where the ignition wire attaches to the coil, leaving a poor connection.

if the coils are bad, wouldn't that affect high speed running also?

Not necessarily...but it could.

anybody got a part number so I can check with Beemer Boneyard or Chicago BMW?


The boneyard seems to be sold out. Click below.

http://www.beemerboneyard.com/12137671896.html

[priapismic]

Pria,
Your symptoms mirror mine somewhat, I think. Would you agree with, "idling roughly, rough warm-up, lower than normal rpm's at idle, need to keep idle + switched in the + position until it warms up good..."

Can't agree with all of your symptoms, Dave. Mine's not rough warming up, and my "rough" idle post title might be tad off. It's more like, a bit "rougher" than it used to be/should be. Just sort of bounces around between approx. 1400 rpm down to about 1000 rpm. And I can switch off the fast idle in about a minute, no problem, no extended warm-up needed.

I'm also hoping somebody can post a test procedure. I've pulled the plug wires a dozen times, I'm just having trouble imagining where a "stick coil" might be pulled out of that big, thick wire.

[BigAL]

Hey Bud - My first post, I just found this board, I spend more time over at bmwsporttouring.com.

I had a similar problem, but had crappy performance on hard acceleration too.

Anyway, I think the best way to check to see if it's the stick coils is to go to your local dealer, and if you can, just try replacing both of them. My dealer's pretty cool, he let me try it before buying them. What a difference! Instant gratification!

The stick coil, if you're still confused, is the black spark plug thing you pull off the primary plug. You might want to check the connector as well, as one of mine was broken and not making a good connection. It's #3 in the picture --


Anyway, try disconnecting one while it's running, see if it makes a difference. Then try the other side. If one being disconnected at idle doesn't change the idle much, it could be that stick.

ALSO -- Since you haven't done a TBS recently, you may have some crappy black buildup on your BBS -- they may need to be cleaned off?

GL--
AL

[priapismic]

Thanks, BigAl! That diagram is most helpful, now I know what I'm looking for to swap out.

And Welcome to the Board!

[cbesey]

FWIW, I just went through the same set of problems with 53K on an '04, plug coil did the trick.

[priapismic]

FWIW, I just went through the same set of problems with 53K on an '04, plug coil did the trick.

Thanks for the info. An update: last weekend I had a friend come over with his Twinmax. We did a fresh valve adjustment, then a TB sync. Symptoms are still there. The bike runs like a scalded cat under full throttle, but the idle is still lumpy, ranging from around 14-1500 rpm down to around 1000. Under low throttle
openings at low rpm, it's really erratic, almost like the dreaded surge! Gasp! Unheard of for a twin spark!

Next week it'll go to a trusted dealer for a look; I'll suggest he test or swap out the stick coils and see where that leads us.