O no not another thread about surging

But yes. So I have had 5 different oil heads all have had some degree of surging from barely noticeable to are you kidding me. My current oil head is a 99R1100RT with staintune exhaust and no cat. which had a pronounced surge at about 1/4 throttle and light acceleration. So I added a O2 sensor fitting and used my Innovate wide range air fuel ratio sensor. I was seeing 15.5 to 1 and leaner. My next step was to check spark plugs valve adjustment and throttle sync ETC. No real change in the surging. My next step was to remove the yellow coding plug and retest. The a/f went to 14.2 to one. On a 2000 mile trip my fuel mileage was 45-50 mpg with virtually no surging. I know everyone has a different approach and results this is just what worked for me.

Very nice and simple data. No spreadsheet?

hendriksgarage said:

But yes. So I have had 5 different oil heads all have had some degree of surging from barely noticeable to are you kidding me. My current oil head is a 99R1100RT with staintune exhaust and no cat. which had a pronounced surge at about 1/4 throttle and light acceleration. So I added a O2 sensor fitting and used my Innovate wide range air fuel ratio sensor. I was seeing 15.5 to 1 and leaner. My next step was to check spark plugs valve adjustment and throttle sync ETC. No real change in the surging. My next step was to remove the yellow coding plug and retest. The a/f went to 14.2 to one. On a 2000 mile trip my fuel mileage was 45-50 mpg with virtually no surging. I know everyone has a different approach and results this is just what worked for me.

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Lake Wales is a nice spot, great view from Bok Tower. When you pull the coding plug on an R1100RT it stops using its fixed maps. If you don’t add a CO Potentiometer, it gets quite rich at small throttle and if you run non-ethanol gas it even stays rich at cruise (E10 is 4% leaner. Below is a friend using an LC-1 to make a riding log of actual AFR. Here is the full report: https://forums.bmwmoa.org/showthrea...and-O2-Sensors&p=894523&viewfull=1#post894523.

It’s possible to get even better performance than no coding plug (and allow E10 fuel) using an Innovate. Which model Innovate do you have?

I have a LM-1. I use 10% ethanol premium. AS long as I have good power 45-50 mpg and no surging I'm good

2000 R1100R surging fix

I picked up a 2000 R1100R with only 17K miles, in great condition. I'm the third owner, and after a few rides, I found out why the previous two owners barely rode the bike (average of 1K per year). It surges so badly between 2800 and 4000 rpm that it is barely rideable. When I test rode it, I thought, "how can BMW sell a bike that does this? It must be be old gas", but compared to my 1987 R80, which is super smooth (and has carburetors), this bike is like a bucking bronco.

So I read a number of articles about it, and decided to:
1) replace the stock Bosch FR6DDC plugs with Autolite APP 3923 plugs
2) remove the pink "CPP" plug, located in the fuse box under the seat, just ahead of the fuses. It looks like a typical square relay, has three prongs, and is marked "Siemens". Then remove fuse 5 (counting from the left side of the bike across), wait 10 seconds, replace. This resets the Motronic computer.
3) disconnect the Oxygen (O2) sensor by unplugging the round connector under the gas tank. Then remove fuse 5 again, wait, replace.
4) install a Carbon Monoxide (CO) potentiometer, connecting it to an unused three prong connector which I found on the right side of the bike under the side body panel that runs from the end of the pillion saddle forward to just above the rear brake fluid reservoir. The lead for the connector runs from the left side of the bike then behind the fuse/relay box to the right side. I ordered the part (BMW 13621461425) from a bike recycler in the UK. Then remove fuse 5, wait, replace. Then adjust the potentiometer. To do this, start the engine and let it warm up and idle. Then use a flat blade screwdriver, and turn the potentiometer screw clockwise until the engine starts to idle roughly. Turn it back counterclockwise until the idle smooths out. At that point, the RPM should be just above 1000 RPM. Do this back and forth adjustment a few times and you'll see where the 'sweet spot' is and where the idle is the happiest.

The intent was to:
1) use spark plugs that a lot of people raved about as a solution
2) force the Motronic computer to use a stored emissions "map" instead of the USA map contained in the pink CPP plug.
3) remove the O2 sensor from the circuit to make the system's loop "open" instead of "closed". The open loop is used in Europe/Canada/elsewhere. The closed is used in the USA.
4) complete the open loop system by installing the CO potentiometer.

The (completely subjective!) results were:
1) the autolite sparkplugs made a big difference. I'd say 50% of the surging was eliminated. Amazing!
2) removing the CPP made a bit more difference, about 20% or so more. The bike was getting smoother and more enjoyable.
3) no difference at all, probably because when the CPP was removed, the stored map no longer used the O2 sensor's data. Bummer, as this was the most difficult step.
4) Adjust the potentiometer properly, and just about 100% of the surging is eliminated.

The bike is now enjoyable to ride. What a difference! After the last step, I went on a wonderful 120 mile ride through the mountains, and it was a blast.

The end result is that the bike is now running as a european/open loop emissions bike, and is running as it should. When it was a closed loop/USA bike, it didn't run as it should. Incredible that BMW could sell a bike with this problem!

Just a bit of clarification regarding your item 2, the fuel mapping plugs: the various maps are stored in the computer, not the plug; the plug is simply a jumper setup (or lack thereof) that tells the computer which one of the various stored maps to use.

On that model, with no coding plug, you'll get best results if you run gasoline without ethanol. Its 4% richer.

roger 04 rt said:

On that model, with no coding plug, you'll get best results if you run gasoline without ethanol. Its 4% richer.

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I don't want to run any engine with ethanol....... buy the good stuff, locally I can get 94 octane, it is worth it

Soooo.... does this also apply to my 2002 1150RT?

Do you mean using non ethanol gas, or fixing the surging? If the latter, I don't recall if the 2002 models had the two spark plug per cylinder setup that was supposed to cure the surging, but if not, the surging fixes I described might help. You'd have to do some research.

jnrugg said:

Soooo.... does this also apply to my 2002 1150RT?

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Basically no, it doesn’t apply to the R1150 which only has maps that use the O2 sensor. In most respects having an O2 sensor is a good deal. The Motronic uses it to constantly tune the fueling. The main problem is that the tuning is to an emissions-friendly air/fuel ratio of 14.7:1, not a performance friendly mixture.

If you simply add an AF-XIED, which shifts the O2 sensor reference point to become richer, you can eliminate the surging AND add torque.