R1100 fuel injection/surging/fixes -- 4 parts
Part 1 of a 4 part series:
My original four part article was originally posted to the IBMWR tech site in the spring of 1996. This new version has been updated to parallel the information in the Zero=Zero procedure found at the same site.
Motronic 2.2 overview (2.4 is almost the same):
The Motronic receives the most important input signals from the Hall-effect triggers (engine speed and TDC) and from the throttle butterfly position sensor (throttle opening angle). The amount of air drawn in is calculated from the throttle opening angle and engine speed. Precise data are determined with the aid of the air NTC (intake air temperature), and oil NTC (engine temperature). CO values on the special version with three-way catalytic converter are performed by the oxygen sensor.
The things to remember here are that the most important Motronic inputs are 1) engine speed, 2) TDC (top dead center, for ignition timing reference) and, 3) throttle opening position.
Many of you have heard about "Cat Code" plugs, and how many have achieved drivability improvements by removing this plug ... but what is it? It's a "map".
You say: "What is a map"? Well, think of the Gulf War "cruise" missiles. They had a "map" electronically installed to compare stored data to what they were overflying on the way to their targets. Motronic is much the same way. The R1100RS/GS series has six (6) different maps available in the later series control units to "custom tailor" parameters to meet emission/country-specific specs. No less than five (5) cat code plugs are specified for R1100RS/GS configurations! Each one is distinctly different in emissions, performance, and drivability.
(Note: CCP configurations are different for Motronic 2.4 installed in R1150 versions. Data on those is unknown as of the writing of this article)
Part 2 of a 4 part series:
Recalling Motronic input sensors and imbedded "mapping", here's what I've learned.
Point 1): Some of you have been pulling the cat code plug (CCP) to see if your bike runs better. What are you REALLY doing? - By removing the CCP, you are installing the "R1100RS without cat map". You are then running in "open loop" mode. Emissions and fuel consumption will increase and the catalytic converter, if installed, may be damaged.
- By removing this CCP, you are defaulting the Motronic control unit to "CO pot installed". Since you have not (presumeably) installed the pot, Motronic defaults to a "presumed" 1.8% CO mixture.
- Prove it: If you bring your bike to your dealer, and have them read fault codes, "1111" will be read, indicating a bad (not installed!) CO pot.
ANY changes you make in the previously mentioned Motronic sensors "could" trip a fault code. To BE SURE the faults are reset, and to assure lingering faults DO NOT cloud what you are attempting to achieve, YOU MUST remove and reinstall fuse #5 "Motronic" to clear the volatile fault memory! Do this EVERY time you change a variable.
In my opinion, removing the CCP is NOT the way to go, assuming of course that you are still running the stock catalytic converter/muffler. I measured CO readings that go from 0-2% CO (with CCP) to 6-8% (without CCP). Running open loop will eventually damage your converter. If you don't care, the cost is yours -- to both the environment and your fuel consumption. Some states, like AZ (mine), have emissions testing. Think about this!
If you have an aftermarket system installed, like my Staintune, your options expand.
Here's the bottom line: The STOCK "with CCP" configuration gives the best OVERALL performance/mileage combo. Although surging (prior to "Zero=Zero") could be detected, this stock combination is the BEST compromise, in my opinion. Without a doubt, it is also LEGAL and safe for a catalytic converter.
I evaluated seven (7) different map configurations on my R1100RS. GS and R folks might experience differences due to compression ratios and cam timing.
BTW: CCP connections were made to configure the Motronic unit in accordance with BMW data. I made up a four-wire jumper connector with spade terminals so I wouldn't have to buy all the different CCPs. Connection pins are related to the pin numbers you will observe on the pin-side of your CCP. Early "Beta" pre-production R1100RSs were "hard wired" for catalytic converters, and have no CCP socket.
1. R1100RS without cat, no CCP connections, CO pot installed:
2. R1100RS with Golden Yellow CCP, 30-87 connections, no CO pot
3. R1100RS with CCP, 30-87 connections, with CO pot (to observe if pot can be coinstalled with O2 sensor)
4. R1100RS - CH (Switzerland) with cat, Dove Blue CCP, 30-86-87a connections, no CO pot
5. R1100GS without cat, Beige CCP, 30-87a connections, no CO pot
6. R1100GS with cat, Rose Pink CCP, 30-87-87a connections, no CO pot
(Note: This CCP when matched with GS Intake Tubes (see http://www.ibmwr.org/r-tech/oilheads/R11pwmod.shtml) can significantly improve mid range torque on RTs and RSs)
7. R1100GS - CH (Switzerland) with cat, Mahogany Brown CCP, 30-86-87-87a connections, no CO pot
Part 3 of a 4 part series:
If you recall part 1 of my previous two posts on this subject, you will remember that the BMW Motronic data I referred to mentioned that there are three most-important inputs to the Motronic control unit:
The TPS is mounted on the outside of the left throttle body. It's the square shaped black module with a connector on its bottom side. The TPS is a rheostat, or variable resistor. Connected to the throttle butterfly, it transmits an input to the Motronic based on throttle opening--anywhere from idle to wide open. The Motronic compares the TPS to all the other sensor inputs to give the proper (we hope) engine management for existing conditions.
The adjustment of the TPS is very critical to engine performance (remember the 3 important inputs!) Adjustment is made by loosening the two socket head screws, the ones with blue paint on them, and rotating the sensor to achieve correct adjustment.
The BMW MoDiTec analyzer is the tool your dealer also uses to set the TPS. First they will clear any faults in the system. Then the technician will rotate the TPS until a particular display is achieved. The screws are then tightened, and the adjustment rechecked by opening and closing the throttle. The tool does not read out the actual voltage from the TPS to the Motronic.
Should you adjust the TPS yourself? For most owners, I would say no. The TPS adjustment is a very precise procedure and has a direct correlation to the throttle butterfly adjustment set at the BMW factory. My subsequent "Zero=Zero" http://www.ibmwr.org/r-tech/oilheads/zero528.shtml article gives full instructions on how to do this, assuming it is _required_. Do not tamper with the TPS or you could damage your engine and void your warranty!
Part 4 of a 4 part series:
Here's how to put together the preceding three part experience I have had with my R1100RS. Please note that I did all my experimenting on my bike, an R1100RS--not a GS with different engine compression and cam timing.
In review, you need to be SURE that ANY drivability problems are NOT a result of a fault in the Motronic system. To be SURE, have your dealer read and correct any faults he detects. Your WARRANTY covers this, as do EPA and DOT regulations.
Assuming a clean bill of health, CONSIDER the following mods:
1. Advanced Ignition Timing:
Most manufacturers set the ignition timing for the typical vehicle with poor fuel quality in mind. Modest performance gains may be achieved by REASONABLE increases in initial advance. Dyno testing on my RS showed a 2-4 HP increase in power across the entire RPM range. Assuming you are NOT experiencing ANY pinging or detonation, you can easily advance the ignition timing by about 3 degrees. Here's how to do it:
2. Valve Lash Increase
If you are like me, try this. I like low and mid-range driveability and throttle response. My R1100RS would not idle for several minutes on cold mornings until I increased valve lash. Increasing valve lash FIXED the problem, and I've lost no discernable top-end power. Increased valve lash is equivalent to closing the valves sooner--"milding" the cam timing.
Set the valves COLD from/to:
Intake: Spec: .006" to: .012"
Exhaust: Spec: .012" to: .014"
Your idle will be MUCH smoother and throttle response immediate but controllable. Increase in valve noise is minimal. Valves will run cooler.
3. Super-Accurate Throttle Body Synch
Many R11 riders have reported the benefits of being anal retentive in the synching of the two throttle bodies. Surging can be dramatically reduced just by synching the throttle bodies VERY precisely. Here' how to do it:
Well, that' it. Except for:
Dow Corning Gear Gard "M" in the tranny and final drive to increase shifting ease This stuff is available in quart bottles at bearing stores. Mix 3-5% by volume in tranny, final drive, and for others, fork oil. Shifting and fork oil "stiction" essentially go away.
Enjoy your 'R'. There's sooo much potential, but it's up to you.