Air-Fuel ratio moving around

[RBMann]

Had the laptop connected to the Power Commander the other day. My R1100S has not been running well, most noticeable at idle. At idle, the laptop show the A/F swinging back and forth between 12.5 to 15.8. The idle gets shaky in the fifteens. A/F is set to 14.4 in the PC III.

O2 sensor?
Bad PC III?

Other ideas?

I might not get to fix this right away as I need to watch my $$$$. After 42 years with the same company and 24 years at the same location, Sunday was my last day of work. They lost the lease and I am out looking for a new job.

[throttlemeister]

How long is the PCIII installed? O2 sensors wear, so if it has been in there for a lot of miles, it may just be starting to give up.

[Bob K.]

Two more ideas:

A vacuum leak can do this. Look over your hoses and connections well.

Also, pull your brass screws out of the throttle bodies and clean both the air screws, as well as where they go in with a good spray cleaner.

[RBMann]

Originally Posted by throttlemeister

How long is the PCIII installed? O2 sensors wear, so if it has been in there for a lot of miles, it may just be starting to give up.

OK, I think the O2 sensor has been in for 60K+ miles. Installed in 2003 or 2004.

[roger albert]

If it's not a wideband sensor and controller, then a continuous to-and-fro signal is absolutely normal. They oscillate by definition and design, a bit like old mechanical voltage regulators. It is not a smoothly varying signal.

[Nitro]

I think the PC does not use the closed loop when at idle.

I had a similar issue on mine until I've richen up the map at low RMP and 0% throttle, problem solved.

Also, why do you run the bike so lean? Do you still have the stock pipes and cat?

I set my PC to 13.1:1 and it runs best at this setting.

[roger albert]

Good catch Nitro.

Yes, 14.4 is a little on the lean side for best running. Not horrible, but on a system as simple as a lambda-N like ours, it will not be tolerant when set that lean. 13 much nicer.

Oh, and good luck with the work thing.

Roger

[boxercup]

Originally Posted by Bob K.

Two more ideas:

A vacuum leak can do this. Look over your hoses and connections well.

Also, pull your brass screws out of the throttle bodies and clean both the air screws, as well as where they go in with a good spray cleaner.

Greetings Bob K,

Bingo! Nice call!

------
Greetings RBMann,

Sorry for the circumstances after 42 years - I wish you the best on your next course of action

Let's try to save you money.

Bike: in question is a 2000 R1100S with 100K.

Symptom: Motronic is now hunting at idle because the engine is not smooth.

You need to do the rule out the obvious first.

I would also add a TB balance and have a look at the TBs and manifold for any air leaks.

A little "Zen and the Art of Finding the Problem Stuff" is all that is needed.

As the Motronic does modify the tuning maps based upon the Lambda signal at idle you can understand why it is hunting if the engine is not smooth.

If you want to test the o2 sensor yourself:



Bad PC III? - Remove it and see how it runs.

Cost: Only Your Time - Your Tools and Your Beers!

Good luck!

Keep us posted!

Hey Find This Guy a JOB!

[8ball]

I reset mine to 14.2 and really cleaned up the "carburation". I think it normal to search around at idle and go in and out of closed loop. Now I have a 2 bros mid pipe and only get exhaust sample from 1 cylinder which is probably a slow sample compared to the o2 sample rate. I don't worry about the search as the bike runs clean and strong. Also I'm in Florida IE. sea level and very warm temps, the bike doesn't run lean.

[RBMann]

I know I am not the normal tuner here. I want smooth running(no surge) and good mileage, not concerned with trying to get more power.

The PC III was installed to try and cure surge with the stock pipes and muffler. The PC uses a wide band O2 sensor. Stock A/F is 14.7 according to makers of the PC. The PC III comes set to 13.8 A/F and some bigger numbers in closed loop cells that it supposedly can't control. Found an article that told how to check a box in the PC software so the added values in closed loop area will be used. I have been making new maps trying to get the stock mileage back while targeting the individual cells to solve surge instead of just dropping the A/F for the whole closed loop area. I have looked at a single cell and increased the value to 50% and then watch the A/F jump as it passes through that cell so it seems that the value can be changed in closed loop. I also have noted that if I add fuel in the idle cell then it becomes hard to start when cold and blows rich smoke out the pipes when you rev it. The A/f reading is very constant at say 3,000 RPMs but not necessarily where the PC is set.

I have tried to work through all the normal stuff sync, valves, timing and air leaks but it seems like some piece is failing. Went back to 13.8 in the PC and the idle is still lumpy. No fault codes found by the dealer. At this time it also has a lot more vibration through the whole rev range but the worst between 3,000-4,000. The vibes are very constant while the lumpy idle comes and goes. They appear unrelated but I don't know. It feels like the timing or sync is off but both check out OK. Maybe a bolt came out of the clutch to cause an imbalance, I just don't know.

At this point work and $$$ are messing with me so I will probably just let it set for a while.

Thanks for the help.

[RBMann]

Originally Posted by boxercup

Greetings Bob K,

Bingo! Nice call!

------
Greetings RBMann,

Sorry for the circumstances after 42 years - I wish you the best on your next course of action

Let's try to save you money.

Bike: in question is a 2000 R1100S with 100K.

Symptom: Motronic is now hunting at idle because the engine is not smooth.

You need to do the rule out the obvious first.

I would also add a TB balance and have a look at the TBs and manifold for any air leaks.

A little "Zen and the Art of Finding the Problem Stuff" is all that is needed.

As the Motronic does modify the tuning maps based upon the Lambda signal at idle you can understand why it is hunting if the engine is not smooth.

If you want to test the o2 sensor yourself:



Bad PC III? - Remove it and see how it runs.

Cost: Only Your Time - Your Tools and Your Beers!

Good luck!

Keep us posted!

Thanks, I always value your advice.

[8ball]

Have you tried cleaning out the idle adjust air screws? It's amazing to me how they can get dirty and affect idle quality. Also you may be having some injector issues at the mileage you have or a failing TPS. Just some thoughts.

[RBMann]

OK, time for an update. Went ahead and bought a replacement O2 sensor to match the one that came with the PCIII. Things are better. The A/F swings about 0.2 to either side of where the PCIII is set. The old one would go 12.5 to 15.8 when set at 14.4 and with the new one it goes 14.2 to 14.6. That seem like a more acceptable range to me and the bike runs better.

I still have the vibration so that must be something else. I am thinking a bad bearing somewhere of a piece broken off the clutch.

After losing my job I went to work for the Seattle International Film Festival. Been doing 40-50hrs./week as the festival is in full swing. The next month will let me know what the normal new reality will be.

Thanks all.

[j.pelc]

I have 2005 BCR R1100s that has remarkably similar symptoms:
Rough idle that often kills the engine
Vibration at around 4000 rpm +/- 300
I have been wondering if the vibration and the idle have anything in common.
My suspicion was due to the fact that no matter how well I balance the TBs at Idle, it drifts 1 to 3 LED's away from center at above 3000 rpm. Not supposed to!

How is it running for you now days?!

[RBMann]

Finally gave up on the PCIII. Removed it and installed an Ax-ifed. Easy install and setup. Bike runs the same as it did with the PCIII but a much more simple system and adjustment. Mine is in the running for worst lean surge award for a stock S. It is a single spark and yours is a dual. Most common poor running issue for the dual spark is a bad stick coil.

I have probably only ridden the S 3-4000 miles since 2012 and no long trips out of town so I am a little out of sync with it these days.

Good luck with yours.

[brentw1]

ok,
with this many miles clean the throttle bodies, see if the throttle shafts or seals are worn,
dirt in the bodies or butterfly edges will make the air flow inconsistent.
this makes the idle much smother on anything with over 50k.
check the o rings between the rubber throttle body mounts and the head Ive had leaks there.
and of course the rubber caps on the tuning ports
check the compression,

[brentw1]

same advise for j.pelc
also when I do the balance I set the cable lengths so that when you come off idle to
about 4k they are balanced then let the bodies close make certain they are on the stops
and adjust the brass screws after, otherwise you are just using the brass screws to compensate
for cable adjustment or issues.

[wswartzwel]

Originally Posted by brentw1

ok,
with this many miles clean the throttle bodies, see if the throttle shafts or seals are worn,
dirt in the bodies or butterfly edges will make the air flow inconsistent.
this makes the idle much smother on anything with over 50k.
check the o rings between the rubber throttle body mounts and the head Ive had leaks there.
and of course the rubber caps on the tuning ports
check the compression,

Rick (RBMann) just did a nice write up of rebuilding the throttle bodies….. So I doubt that is his issue.

[roger albert]

My suspicion was due to the fact that no matter how well I balance the TBs at Idle, it drifts 1 to 3 LED's away from center at above 3000 rpm. Not supposed to!

You need to adjust the cables.

[wswartzwel]

Roger Albert??? Introduce yourself newby …. wonder if someone hacked his password.