1997 R1100RS misfire only at 4000 to 4500 rpm

Have you checked your plugs?

It only takes one fill up of bad gas to mess the fuel filter. Just sayin.

Plugs and plug wires cleaned and inspected on the road.
Talked to a moto buddy and he sez concentrate on the ignition. Didn't think much of the gas situation. Cycle under load is mis-firing- hills and 5th gear only.
I am looking more closely at that. Hate, hate taking the tank off and opening it up. Yes, I have the metal upgrade quick disconnects, but I'm working in a parking lot with no garage or workbench.

After getting home and previous to wrenching, I did my usual research on our site. Regarding Motronic and ECM on oilheads. My guy has 2.2 and I didn't know how much it adjusted to fuel, air, temp and all that. Thought the poor fuel had influenced the timing/spark/fuel delivery? Some people said it does not 'learn' at all? Some said, 'a little'? I have noticed that each time I have disconnected the battery, it coughs and misfires for first 2-3 miles. As I go through gears and travel a bit, it smoothes out. I did the 2 turns of the throttle, with key on, but not started. I don't know what this has done for Ol' Mean Green and my current problem, but the Motronic 2.2 is doing something during that adjust period.

Update

Disassembled and cleaned and inspected ignition system. Testing. Found spark plugs way out of spec- gap doubled!
Symptom improved, but did not disappear.
Sent out injectors for cleaning while down and apart.
Back together this weekend, then more testing underway.

Hopefully you replaced the plugs with new ones, and didn't just reset the gap (0.031").
As a partial tho relevant tangent: MANY of us (myself included) have ditched the Bosch plugs in favor of the Autolite AP3923.
Also have a close look at the spark plug cables themselves, especially where the little clips grab them to route them along the frame: damaged insulation will cause a misfire. It isn't unreasonable to find that plug wires that are over 20 years old could be intermittent internally.

Bad gas or water in the gas is still suspect; water can do weird things to filters. As much as we hate alcohol in the gas, you might try some Heet (red bottle) in the gas to break down the water, or just drain the tank completely (the bottom left side may still have contamination) and use fresh quality gas.

BTW, yes the Motronic does learn and update the fuel/ignition mapping continuously; Roger04RT has demonstrated (by actually capturing the data and plotting it, and posting it here in previous threads) that the older bikes do have about 2 minutes of "setup" time after starting before they are ready to ride.

Another tangent but also relevant - Have you verified valve clearances and throttle body sync? Those will affect not only performance "now" but also how the computer adapts to conditions.

UPDATE: Broken timing wheel on alternator pulley!

Dudes!
Symptoms went away with gapped plug. Using cycle for around town. Now, on another long trip the same symptoms come up. Long trips, in 5th gear on Hwy, starts misfiring at 4000 rpm. Higher rpms, lower gears get rid of it. Euro-Tek in OKC (on may way from AZ to Arkansas) says the only clue he has is the timing sensor- the HES unit. Symptoms get worse! Usable gears and rpms become less and less. OK. Order a new unit from bbone, and plan to install. Taking off the alternator pulley, the timing window piece on back slips off. Two piece pulley? Doesn't seem right. Notice in a Chris Harris vid that he says, "...the tack weld can fail." Exactly. Took it to local welding shop and the put them back together. Still futzing with timing and that plate on HES timing sensor! Can't get it right. Can anyone link to voltmeter method? I tried it and it still isn't right. Can anyone FedEx me a Hager Box, if it is critical? I'm visiting friends, and they are tired of my bike in their driveway :-(

It's only 1.5 degrees from center either direction.

No need for the hagar box

This is how I do them:


Ignition key off
Unplug the headlight (optional)
Remove the flywheel viewing plug in the bell housing
Remove the alternator belt cover
Key on
On the 1150: Rotate the crank by hand to a little before the 'S' mark (5° BTDC) on the flywheel
On the 1100: Rotate the crank by hand to well beyond the 'OT' mark (TDC) on the flywheel
Turn the ignition key on - the fuel pump will cycle normally
Rotate the crank very s-l-o-w-l-y by hand until the fuel pump cycles again
On the 1150 ROTATE CLOCKWISE until the fuel pump cycles again
On the 1100 ROTATE COUNTER-CLOCKWISE until the fuel pump cycles again
The crank is now at the hall sensor trip point - in this case that is also the static timing point
Look at the flywheel marking to see where the static timing is set
Adjust if necessary


*** make sure you torque the pulley nut to 50 NM or you risk it slipping and tearing of the index tab***

Wanted to add to my description that I think the alternator position was not set with torque wrench. While dis-assembling, it seemed very tight. This may have led to my pulley coming apart into two pieces.
I plan to take pulley back off, next. I want to inspect that installation carefully. Plus, I can't seem to move base plate effectively with pulley and belt in the way. Right now I am kinda prying it CW and CCW with a trim screwdriver? Not a fine adjustment.
Thanks, will try that with the fuel pump.

The crank is now at the hall sensor trip point - in this case that is also the static timing point
Look at the flywheel marking to see where the static timing is set
Adjust if necessary

Adjust the plate?
static timing point? Can you describe what that means to my adjustment process. I need TDC of crank, to coincide with the 12v signal from sensor. Fuel pump on tells me sensor is sending 12v?

greenmachine1100 said:

Wanted to add to my description that I think the alternator position was not set with torque wrench. While dis-assembling, it seemed very tight. This may have led to my pulley coming apart into two pieces.
I plan to take pulley back off, next. I want to inspect that installation carefully. Plus, I can't seem to move base plate effectively with pulley and belt in the way. Right now I am kinda prying it CW and CCW with a trim screwdriver? Not a fine adjustment.
Thanks, will try that with the fuel pump.

The crank is now at the hall sensor trip point - in this case that is also the static timing point
Look at the flywheel marking to see where the static timing is set
Adjust if necessary

Adjust the plate?
static timing point? Can you describe what that means to my adjustment process. I need TDC of crank, to coincide with the 12v signal from sensor. Fuel pump on tells me sensor is sending 12v?

Click to expand...

Yes, adjust the plate to the fuel pump as per instructions

FYI: the hall sensor signal sinks to ground, it does not give you a 12v signal.

Sinks to ground = switches to negative
Applies to the Black - fuel pulse & Orange - spark pulse

Biggest Clue Ever!

I see my thread has 220 views. It is nice that many people have thought about this diagnosis. I appreciate all the cognoscenti (you know who you are) with suggestions.
OK! Still haven't rid myself of this problem. Stated above, new ignition parts- same symptoms. Some days worse, some days bad. To add some information:
Gears 1,2,3 work well. As I'm accelerating, cycle fuels and fires 2k to 6k rpms. Trouble is dying engine when I try to hold a steady speed in 4th and 5th gear, between 3800 and 4500 rpm. If I push cycle up to 5k, it generally runs smooth. This means on a highway situation, I need to go slow (55 in 3rd gear, or 95 in 5th gear) What I need to do, to overcome this sputtering and dying, is jiggle the throttle. goose it. Sometimes just a little crack, over and over. Sometimes wanking it, like a centimeter or more. Push it, push it, until it gets above 5k. It is like I'm tricking it into accelerating. The engine responds to acceleration, but doesn't like steady speed (almost exclusively between 3800-4500). Covered 2500 miles on my trip, playing with the throttle! Developed a callous on the top ridge of my palm!! Only covered 250 miles one day, because my arm/hand was so tired!!! Crazy.
Now the best clue!

It cleared up in the mountains! Didn't go away, but became significantly reduced. 4th G worked in all rpms, and 5th could be used with a little of the goosey-goosey technique. It cleared up in Colorado, through Wolf Pass, it cleared up in Flagstaff, AZ as soon as I passed 6000 ft. Now, what does that say about low atm. pressure or less oxygen?!? Both those areas were higher, cooler, and less humid.
Before you say 'venting'? Here is the last place it cleared up- in the Valley of the Sun, Phoenix. No elevation, not cooler, BUT zero humidity. (In fact, it was 120 F on the last 100 miles. I had a small heatstroke close to home.)
Since I ride in Tucson/AZ almost daily, since I ride in 1,2,3 G on my commute/errands, this condition may have been long time present. Only noticed it on long rides. (Las Vegas in Jan, this trip from AZ to AR)
Here's what I notice from this- all the places it ran fine (problem exists, but hardly noticeable) are dry. All the places the engine was dying were humid (and hot. Oklahoma, Missouri, Arkansas,Kansas)
This must be an, "A-Ha!" clue for someone?

O, one last thing about venting. I rode it with gas cap just cracked open for a hundred miles. Didn't change a thing.
Is my little baby born and bred in Arizona, and the engine/motronic won't run in high humidity? Haha!!

I vote faulty temperature sensor causing it to normally run rich but at altitude it leaned out.

Hmm, does a bike at altitude not need a leaner mixture? That's what I noticed when I used to have carburetted bikes.

BC1100S said:

Hmm, does a bike at altitude not need a leaner mixture? That's what I noticed when I used to have carburetted bikes.

Click to expand...

Yes. I stated the issue backwards.

greenmachine1100 said:

Would you be talking about the Air Temp Sensor in the airbox?
The engine temp fluctuates between 5 bar and 6 bar, and I was riding in godawful heat.
The stalling generally got worse as the day grew hotter, for sure.

Click to expand...

Typically the issue is the engine temperature sensor attached to the engine case, but a faulty air temperature sensor might do it too. The ECU uses the engine temperature sensor to tell it whether the engine is cold or fully warmed up. Exactly what it uses the air temperature sensor for I am not sure but it does affect mixture.

Update on my engine problems:
Exhaust is back to together with a new 02 sensor. Going to test it on the highway with rpms and gear matching my problem in the morning.
Got a cool little diagnostic tool from MotoBins in UK



Works great! Takes power from onboard plug, instead of battery. I got a stored error code! 2344 = Lambda sensor open circuit
My original problem? IDK "Open" means I need to inspect the wiring for a break?
I'm going to run it around tomorrow morning, park it, and plug in tool again. See if it is a persistent fault code, or just left over from before I affected any repairs. Then I will install new air temp sensor and see if that has any effect.