Fuel Injection FAQ

Started by Adam #1001, compiled & edited by Kristian #562
Please read the Disclaimer before attempting any work in this FAQ.
Last Updated: 4 April 2007, by Winter #1935

For other relevant FAQs:


When BMW released the newer GS / Dakar / CS models of the F650 in 2000, it came with Fuel Injection. Some considered this to be a step forwards, and some a step backwards. This FAQ goes into detail on the Fuel Injection unit. FI controls the fuel/air mixture very accurately (emission control), is compact (design), and deals well with big single-cylindered engines where air can flow too slowly for efficient carburetion (performance). Given BMWs fondness for electronic engine management systems, the fact that FI integrates easily here makes it an obvious choice. The ECU provides mechanics with a superb diagnostic tool, and engine mapping software can be upgraded easily (and thereby hangs a tale).

Note: It is perfectly normal for your revs to remain higher than idle speed (i.e. 1800-2000rpm) as you come to a halt with the clutch in. This may have been one of the things BMW did to help prevent Surging and Stalling problems. One theory is the wet clutch in the F650 bikes results in clutch drag - keeping the revs higher until you have completely stopped. Once you have stopped the revs should drop down to 1500rpm.


Fuel Injection systems contain many sensitive electronic components. Messing around with this system can result in many problems with your bike and engine, or could even disable everything completely. In some instances this FAQ contains technical content that is not about engine or bike mechanics, but is about computer systems.

Also note the fuel injection system plays an important role in emmisions control. Messing with your fuel injection system may result in your bike's emmisions getting worse. In some countries this may be illegal - the information provided here is to aid in understanding how the fuel injection system works, how to maintain it, etc.

Finally, note that fuel is flamable... no nekkid flames, and be careful - if you do manage to set your bike alight, please take a photo of it so we can place it in this FAQ as an example of how stupid you were to set your bike alight!

Section 1: History and Development


The Fuel Injection unit has had many names over the years. This is due in part to confusion over comparisons to other BMW related FI systems. The following list is by no means a conclusive list of the names, but should explain at least where some of the confusion comes from:

Motronic There seems to be a misunderstanding by many. The F 650 G/S does not have MOTRONIC. As BMW use the name: "Motronic Control Unit" and "Steurgerat Motronic" all over in the official "Stromlaufplane F650 GS/GS Dakar........" no wonder I/ we use the same name for that unit but it is NOT the same unit as used on the boxers. Not even made by the same company, Hella BMS used on the GS and Bosch Motronic used on the boxers. BMW uses the Bosch brand name "Motronic" for both, except in the workshop manual, where they call it a BMS unit.
ECU Electronic Control Unit - A common name used for all sorts of FI systems. The ECU is also a fairly common name for describing the smaller and simpler electronics associated with carb engines.
EFI Unit Electronic Fuel Injection Unit
Fool Injection A "pet" name of the BMS-C used by some members of the Chain Gang. The use of the term fool is in suggestion of many things, based mainly around the mess BMW made with the earlier model BMS-C and software.
BMS-C BMW Motor Steuergerat - Compact. The term Steuegerat means controller.
BMS-C II This is simply the second version of the BMS-C. See this history section for more information.

Other names are often confused with the FI system, include MoDiTec (a device used by BMW to talk to the BMS-C). Within this document, the FI system on the F650 bikes has been refered to as the BMS-C unless otherwise noted. This is also consistent with the BMS-K used on other BMW motorcycles.

History of other units



According to BMW brochures: the new BMS-C II engine control system, with its quintuple calculation speed, considerably reduces fuel consumption and exhaust emissions. At high speeds this makes quite a difference. Cruising at 75 mph the reduction compared to the predecessor amounts to 0.7L to 4.3L per hundred kilometers. And the torque curve has been optimised into the bargain while meeting EU-2 emissions standard with ease.

Section 2: Blood and Guts (Internals)

This section contains the real blood and guts of the BMS-C - what we can work out anyway! Most of this information is available through various sources already on the Internet. The rest has been worked out by simple deduction. The image on the right has been modified. The original image BMW used in a service bulletin was inaccurate (in two ways: Firstly it was used in the context of a dual spark bike, and secondly the BMS-C was referenced as a BMS-K).

You can see the Blue lines are the things the BMS-C controls, and the Red lines are the sensors providing input to the BMS-C. Note: The red temperature light is shown in the middle right of this image. Some inputs appear to be missing (starter button).

You might want to check out the GS Documentation FAQ for more information on the wiring diagrams of the single spark fuel injected bikes.


The sensors provide input to the BMS-C. Values from each sensor are sampled at a certain rate (unknown) and fed into various calculation. These calculations determin the amount of fuel injected and various other things.

Inductive Sensor (RPM)

BMS-C Pin Colour Usage In English Please!
8Brown and yellowRPM- Inductive sensor
18Yellow and redRPM+ Inductive sensor

According to the Moto One Performance Notebook page for the F650 GS-Dakar-CS, the RPM sensor is a single pickup sensor on the flywheel. This sensor apparently is used to detect engine rotation speed (i.e. RPM) and cycle position. The cycle position is apparently established by the fact the engine slows down as it comes up to TDC on compression, and accelerates away from TDC on firing.

Air Temperature / Air Flow Sensor

BMS-C Pin Colour Usage In English Please!
14Brown and blueTANS- Air temperature sensor
23Brown and yellowTANS+ Air temperature sensor

This sensor is located in the "snorkle", airbox or whatever you want to call it. On the GS/Dakar, you can find it by removing the RHS faux tank. Check the Air Filter Location FAQ for the Air Temperature Sensor. Note: At this point in time it is unclear if this sensor is for air temperature or airflow.

Coolant Temperature Sensor

BMS-C Pin Colour Usage In English Please!
3Brown and redTMOT- To water temperature sensor
4Brown and greenTMOT+ From water temperature sensor

Engine temperature is based on the coolant temperature sensor. This sensor can be found on the RHS of the engine, just near the coolant bleed valve. This sensor has 4 pins, however only two pins are used. This sensor connects to the BMS-C unit. The BMS-C unit then controls the Fan and temperature idiot light. Note: Because the engine temperature is based on coolant temperature, rapid changes in oil temperature will not be detected. See the Coolant Change FAQ for more information.

Air Pressure Sensor

There are no pins on the BMS-C connector to the Air Pressure Sensor. This sensor is found on the BMS-C mainboard itself. This is the Motorola MPX4115A Manifold Absolute Pressure Sensor. According to Haakon's information and the datasheet:

MPX4115 : Integrated Pressure Sensor

The Motorola MPX4115A / MPXA4115A / MPXS4115A series Manifold Absolute Pressure (MAP) sensor for engine control is designed to sense absolute air pressure. Motorolas MAP sensor integrates onchip, bipolar op amp circuitry and thin film resistor networks to provide a high output signal and temperature compensation. The small form factor and high reliability of onchip integration make the Motorola MAP sensor a logical and economical choice for the automotive system designer.

MPX4115 Features

  • 1.5% Maximum Error over 0° to 85°C
  • Ideally suited for Microprocessor or MicrocontrollerBased Systems
  • Temperature Compensated from 40° to +125°C
  • Durable Epoxy Unibody Element or Surface Mount Package

Troubleshooting: Because this sensor is built into the BMS-C itself, there is no easy way to test it. The only method that can be suggested is to swap the BMS-C with another similar model. You could open the BMS-C itself, and using a voltmeter check the resistance on certain pins and compare to the MPX4115A datasheet.

Lambda (O2 / Oxygen)

BMS-C Pin Colour Usage In English Please!
10Gray and black15 Lambda sensor
16Yellow31 LBDA Lambda sensor
17BlackLBDA Lambda sensor

Located in the exhaust header pipe, this sensor is used to detect the oxygen levels in the exhaust.

Throttle Position

BMS-C Pin Colour Usage In English Please!
15White and redDKP- Throttle position potentiometer
24White and blackDKPS Throttle position potentiometer
26White and greyDKP+ Throttle position potentiometer

The TPS (Throttle Position Sensor as it is sometimes called) is located on the throttle body. It detects the position of the throttle, and hence is probably the most direct input a rider has to the BMS-C.

Starter Button

BMS-C Pin Colour Usage In English Please!
12Black and yellow5D Right combination switch (start)

The starter button is a very simple on / off sensor.


Ignition Coil?

BMS-C Pin Colour Usage In English Please!
1BlackZ1 and kl 115 To ignition coil and rev. counter

It is unclear if this is a control or sensor. Given there is already the Inductive sensor (RPM), this is more likely used to start the engine.

Cooling Fan

BMS-C Pin Colour Usage In English Please!
2White and yellowFAN To fuse F3 and cooling fan

The BMS-C will emit a signal on this pin when the coolant temperature sensor reaches 102°C (225°F). Please see the Overheating FAQ.

Throttle Valve Actuator

BMS-C Pin Colour Usage In English Please!
5Black and violetD Throttle valve actuator
6Green and violetA Throttle valve actuator
11White and violetC Throttle valve actuator
13Violet and yellowB Throttle valve actuator

You know that thing that sounds like an aerial going up / down when you turn the ignition on / off (or switch the kill switch to the enable / disable position)? That is the throttle valve actuator. Note: It is not recommended to switch the bike on/off or flick the kill switch on/off rapidly, as this could result in problems for this "control".

Coolant Indicator Lamp

BMS-C Pin Colour Usage In English Please!
19VioletKT Collant indicator lamp

Also known as the temperature idiot light, the BMS-C will turn this light from off to on if the coolant temperature rises above 118°C (245°F). See the Overheating FAQ for more information.


BMS-C Pin Colour Usage In English Please!
21Blue and yellowVFZ Speedometer

Fuel Injector and Pump

BMS-C Pin Colour Usage In English Please!
20Yellow and blue15 Fuel injector earth
22Grey and redTEV Fuel evaporation valve ??
27Green and brownEKP (15) Fuel pump
28Green and blue15 Fuel injector +

The fuel injector is always (when the ignition is turned on) connected to +. What opens it is when it is earthed by the ECU. The Techlusion box prolongs the earth time.

BMS-C Unit Images

The following images are from Robert's Page and are of the BMS-C:


Diagnostic Plug and BMS-C Connector

There are several connectors associated directly with the BMS-C. The first and most obvious is the round 10-pin diagnostic plug. The second and fairly obvious connector is the that from the main wiring spool to the BMS-C itself. The following tables are based on information from Robert's Page. BMS.pdf

1Brown blackConnects to BMS-C pin 7 - diagnostics
4Brown orangeCommon earth
6Red whiteCommon + from Ignition Switch

Table 1: Diagnostic connector pin-outs

PinColourUsageIn English Please!
1BlackZ1 and kl 115 To ignition coil and rev. counter
2White and yellowFAN To fuse F3 and cooling fan
3Brown and redTMOT- To water temperature sensor
4Brown and greenTMOT+ From water temperature sensor
5Black and violetD Throttle valve actuator
6Green and violetA Throttle valve actuator
7Brown and blackDIAG Diagnostic Plug
8Brown and yellowRPM- Inductive sensor
9Brown and orange31 Common ground (Battery -)
10Gray and black15 Lambda sensor
11White and violetC Throttle valve actuator
12Black and yellow5D Right combination switch (start)
13Violet and yellowB Throttle valve actuator
14Brown and blueTANS- Air temperature sensor
15White and redDKP- Throttle position pontentiometer
16Yellow31 LBDA Lambda sensor
17BlackLBDA Lambda sensor
18Yellow and redRPM+ Inductive sensor
19VioletKT Collant indicator lamp
20Yellow and blue15 Fuel injector earth
21Blue and yellowVFZ Speedometer
22Grey and redTEV Fuel evaporation valve ??
23Brown and yellowTANS+ Air temperature sensor
24White and blackDKPS Throttle position potentiometer
25Red and whiteRed and white Common + (Battery +)
26White and greyDKP+ Throttle position potentiometer
27Green and brownEKP (15) Fuel pump
28Green and blue15 Fuel injector +

Table 2: BMS-C connector pin-outs


There is a third and lessor known connector on the BMS-C mainboard itself. If you take a look on the top right of the image of the mainboard, you can see a small set of solder points (two rows of five silver lines). These connect to the JTAG port on the CPU. What do they do? The JTAG connector allows you to connect a computer directly into the CPU and manipulate what is going on. It even allows you to change the contents of things like flash memory. These connectors are installed on most modern electronics devices, allowing easier design and programming.

What About The BMS-C II?

There is currently no information on the connectors for the BMS-C II. The diagnostic connector is the same. However due to the second spark plug, the BMS-C II Connector has not yet been written about. It is also unknown if the BMS-C II has a diagnostic JTAG port. Given the JTAG port on the earlier model BMS-C, it is fairly safe to assume the BMS-C II has a JTAG port.

Software Versions

General Comments

When you look at the internal code for the BMS-C, it appears to be written by two different programmers (or groups of programmers). The first part appears to be using the standard programming techniques for the CPU used in the BMS-C. The second part uses a completely different set of techniques. This is probably consistent with Hella creating a set of "system" libraries for using the BMS-C, and BMW creating the main code. There are only small changes to the internal code in each software versions. This is consistent with observations made.

BMS-C Software Versions

(Source: http://f650gs.da.ru/)

The following table has been shamelessly taken from the robertosat website:

Rev limit
Open Loop
Beyond RPM
5000-3611 none 1999/2000 Europe 1300 7500 2000 absolutely surgefree; bike is running hotblooded; best driving comfort; highest fuel consumption; in combination with OLD INJECTOR often stalling; rarely stalling with NEW INJECTOR
5000-3611-w none   1300 7500 2000 advanced spark map; there is feelable more torque and a lower fuel consumption when driving slow, e.g. city traffic.
7000-3601 9.3 spring 2001 1400 7500 4500 This junk spoils you with a lot of SS (Surging & Stalling); bad throttle response; backfiring; best(!) top speed and worst driving comfort
8000-3608 10.1 September 2001 1400 7500 4500 No stalling and almost no surging, but the F650GS will behave like a Diesel vehicle - no power, a lot of vibrations and, of course, a lower fuel consumption. In addition the engine is producing feelable more heat; bad throttle response;

BMS-C II Software Versions

FI Maps

The following FI maps have been extracted from various software versions. The offsets of these maps change from version to version. Please note: The original FI maps from the robertosat website are not entirely correct - they are based on linear index values (100, 200, 300 ...), however the index values used in the FI software are not linear. The FI maps shown below have the correct representation.

Version Number Dyno Run Date Spark Map 11*14
Starting Offset

Custom Software Upload

Robert B., Austria, edited by Kristian #562, 27/11/01

There are three methods you could use to upload new software to your BMS-C:

  1. Use the instructions below to remove the EEPROM chip and either have it reprogrammed, or reprogram it yourself if you know what you are doing.
  2. Use a MoDiTeC or Group Tester 1 (GT1) - these special computers communicate through your diagnostic plug, and are very expensive "special" BMW computers.
  3. Use the JTAG port on the mainboard - no one has done this yet, so if you have the knowledge and you do have success, please let us know the details.
Warning: Uploading software may damage your engine or prevent it from working
Messing with the software in your fuel injection system could cause the following:
  • Damage to your engine?
  • Increased emissions
  • Decreased performance
  • An engine that will not run at all
  • Surging and Stalling
Reprogramming the EEPROM
  • In early 2000 the bikes that were shipped in Europe had a built-in software that gave the F650GS more noticeable torque and there was absolutely no surging or backfiring. The only problem was sometimes the bike stalled. The rest of the story is written in other FAQs on Surging and Stalling.
  • As I was very unhappy about the surging I decided to try and upload the old software back again.
  • As I was not able to communicate through a serial connection with the HELLA Motronic, I had to remove the EEPROM. To do this you have to unplug and open the box housing the EPROM.
Here is a Photo of the EEPROM. When removing the main board you have to take into consideration that the plug is fixed to the metallic casing with some glue. That glue has to be softened by heat, but not in direct contact, e.g. a hair dryer. In addition there is a metallic grounding connection which has to be cut. Both can be seen on the attached figure.
Here is a photo of the what you should cut
The metallic grounding is connected to the (pin marked green) on the plug and the attachment is located under the plug (position is indicated by blue arrow). That connector is nearly inflexible and the other end is mounted to the metallic housing. You have to have a very special tool to remove it. As we did not have that tool we had to cut it. As a replacement for the connector we soldered a cable (red arrow) onto the pin.
Then we soldered out the EEPROM and read the current software using the equipment of a chip tuning company. That software was version 9.2. As no one had any idea how to remap the existing software, we decided to downgrade to the old European software.
  • You can get a copy of the software at http://www.obd-tuning.at/. This company has a lot of experience in doing this. I believe http://www.bbpower.de has also got a copy of the old software.
  • The review of the old European software was made with MISTERED by Hansen at http://www.freemred.de/main.htm. Every software version is 512 k bytes and is not encrypted. MISTERED is software which can read the contents of the EEPROM and you can even modify it. In addition it is possible to make a graphic overview of the FI mapping. First you read the EEPROM's contents into a PC. You then have a 512 k byte file on your PC. In addition to the standard abilities of MISTERED to modify the file, MISTERED can also make a graphic interpretation as shown above. This Graphic Image of the mapping is very helpful in identifying the various parts of the file as it consists of a program and the "Kennfelder". "Kennfelder" is the mapping table which is tells the program how rich the fuel/air mixture has to be for various conditions.
  • Now my F650GS is running with the old software in combination with the new injector #0280155788. I have full power/torque across the whole rpm range, reduced vibrations and no surging even down to 2000 RPM. The only disadvantage is a higher fuel consumption of about 25 percent.
  • Initially the stalling reappeared but after about 500 miles of driving the frequency of it decreased dramatically. I can now say I have a perfect running bike and would recommend anyone still plagued by surging and stalling to go the same way.
  • There is no reason why this approach should not work on bikes in the USA or the UK. http://www.obd-2.com/routepit.htm
  • Returning back to the original software. What you need is a special soldering-kit, a special forceps, an EEPROM reader/writer and a PC. You can find the EEPROM Part No at http://www.geocities.com/robertosat/. So a specialist can tell you which size of forceps and so on is needed. You cannot download the software on the net but you can ask Haakon in Norway for it. Some weeks ago he posted that he is willing to do it. IMHO it would be safer to send the DME to http://www.obd-tuning.at/. Mr. Baumgartner has a lot of experience in doing it and he is a very careful working man. The last time the whole procedure took him about 15 minutes. To me it would take about 2 hours and I am not sure if it would work afterwards. You can also ask Mr. Baumgartner if he is willing to send you the programmed EEPROM. Robert.
  • No question, if I couldn't have managed to get the old European software I would have bought that Fuel Nanny at that time. But with my present knowledge I wouldn't buy that FN. So please have a look on the net for power boxes. There are a lot. Maybe the most famous is one is the POWER COMMANDER . When you read the reports about it you will see that it is very costly to tune an engine. And it is much more difficult than it is described at Techlusion's site. Besides there is always the possibility that you destroy the engine with wrong settings. In addition it is the statement of many real experts that the brown curve on the DynoJet run at Techlusion must be a fake. So it is my advice that you get the 5001. That 5001 was designed by BMW for a perfect open-loop running engine.

Section 3: Misc

Resetting the BMS-C

"When folks have stalling, surging or uneven running problems and a sensor is not working correctly or the idle valve sticks, the software uses a substitute value setting and the fault is recorded in the BMS Compact unit. Disconnecting the battery for a few minutes (Removing JUST the negative terminal (for a while) is all you need to do if you want to clear the "brain") deletes those recorded faults and resets the unit to its factory setting. That is all that is required for a reset. No twiddling throttles, no running engine till fan comes on. If it keeps happening then the owner should take the bike to the dealer and let the BMW MoDiTeC establish what the problem is." Trevor #999's BMW Contact... See the Battery FAQ on how to get access to / disconnect the battery.

Method 1: Removing the BMS-C connector (easy-ish)

  1. Turn your key / ignition switch to the OFF position first!
  2. Remove the seat from your bike
  3. Undo the large multi-pin connector off the BMS-C itself.
  4. Wait 15 minutes, then reconnect the BMS-C
  5. Note: If you are staying somewhere and you do not want anyone to ride your bike away, you can even take the whole BMS-C unit with you!

Method 2: Disconnecting the battery (annoying)

  1. This OUTDATED procedure has been used with some success in the past but according to Trevor#999 Contact at BMW, it is actually incorrect.
  2. Remove the faux tank plastic to get to the battery
  3. Leave the battery installed, just disconnect the negative terminal 100% for 2-3 minutes. Note the clock will re-set to 12:00.
  4. Pretend your bike has just gotten a FI software upgrade and the battery is disconnected.
  5. Re-connect the battery positive 1st, put the plastic side panels on and roll the bike outside to fresh air.
  6. Key on ignition to dash lights "on" position (DON'T START!).
  7. Fully twist throttle 2 times hitting the min and max levels, release throttle completely. (This part of the procedure is contentious. ed)
  8. Start bike with NO THROTTLE, leave bike alone (don't touch throttle) idling for 5-10 minutes until the fan comes on. (Again a contentious issue)
  9. You are done. Ride away or shut down bike.

Method 3: Removing the fuse (easy)

  1. The other "simple" method I would suggest is removal of the fuses. Can not remember which fuses, but the 15A and 10A fuses ring a bell (remove both fuses just to be sure). The manual only warns you to switch off the ignition before changing fuses and never to repair a fuse.
  2. Once the fuse has been removed, wait 15mins then plug it back in
  3. Note: This method has not yet been confirmed. However if the ECU does get power even with ALL the fuses removed, I would be somewhat concerned, as this could result in damage to the ECU if there was a short circuit somewhere.

Why do I need to wait 15mins?

Has anyone experienced any problems with the suggested reset methods?

Should I let the bike idle after a reset?

Idle Speed

I have just purchased an '00 F650GS, but it seems to idle around 1500 to 1600 rpm. Is it easy to adjust and can someone tell where to adjust it?

Can the Fuel Nanny adjust the idle speed?

How do I fix a fast idle then?

Any other methods to adjust the idle speed?

Poor Idle and throttle response from your GS?

What is the Idle speed for the fuel injected F650?

Fuel (Types and Running Out)

Should I use Premium or Regular fuel?

Octane Ratings

by Marty #436-Chicago-97 F650F, Flash#412 & Sojourner

There are 3 standards to grade fuel: RON, which is the original standard. MON which is a more recent standard and PON, which is a blend of the two (and used in the US). The conversions between the different standards are not always straight forward, but generally"

95 RON ~ 91 PON (as used in the US)
85 MON ~ 88.5 PON

So, next time check what the fuel pump says (RON, MON or PON). Sojourner

There is NO reason to use gasoline with octane any higher than what it takes to keep your engine from pinging. Expensive gas does NOT make more power. The higher the octane, the slower the gas burns (to prevent detonation). High compression engines are prone to pre-ignition. High octane prevents this phenomenon.

You might as well burn a paper sack of dollar bills in the driveway before you leave home and see if your vehicle runs any different as to fill it with $4/gallon gasoline (unless it has extremely high compression). They will both have exactly the same effect.

For a CAR with an 8:1 compression ratio, this number is at normal atmospheric pressure. Depending on the boost pressure, yes, 91-or-higher octane as per advisory may be required. That is the reason lots of turbo engines have knock detectors linked to water injection systems.

What about MTBE in the GAS? What about Ethanol?

What about Injector Cleaners?

What happens if I run out of Fuel with an FI bike?

Can I use OPAL fuel?

FI Links

Throttle Body

How do I remove the injector?

  1. Let your bike sit overnight without running it (this should allow the pressure in the fuel line from the fuel pump to the injector to bleed down. However always assume that the line is pressurized when removing the injector, i.e.; wear eye and hand protection)
  2. You are doing this outside with a fire extinguisher nearby arent you? The regulated fuel pressure to the fuel injector on the F650 GS is 3.5 Bar (50.75 pounds per square inch). The fuel pump is capable of developing a pressure much higher than that. The fuel system remains under HIGH pressure at all times, even with the ignition off and the bike left unused for many days. Wear safety goggles and protective clothing at all times when working on it. Hoses under pressure can slip off, spray fuel, and fling hose clamps off their ends at velocities approaching that of a speeding bullet without any warning. Flying hose clamps can create sparks and ignite the fuel spray when they hit a solid object. Ill repeat: work outside in a well ventilated area with a fire extinguisher handy.
  3. Remove the side panels and faux-tank from the front end. See the GS Frame Fairing FAQ for how to do this.
  4. Carefully remove the clip from the injector ((you have to reuse the clip) and the fuel line leading to it (CAUTION! keep your face away from the immediate vicinity in case there is still pressure in the line). The injector looks like the long one in this photo.
  5. Gently Pull out the injector.
  6. Fit new one. See custom fixes for Surging and Stalling or use a later BMW part.
  7. Replace bits and bobs. Pay attention to the fuel lines, they may leak and barbecued prairie oysters are not nice if theyre your oysters.

Cleaning the Throttle Body

  1. A few weeks back I decided to replace all the fuel lines and the intake manifold on my GS. I figured they were nearing their potential use by date and I did not want a failure, while on the road etc. So.....I replaced all the parts and while I was at it, discovered that after 60,000km, my throttle body looked a bit grungy.
  2. airbox side and injector side
  3. So I took to it with my CRC Carby Clean in a spray can, and gave it a good workover. In particular I made sure I cleaned the Idle Valve air passages, which were also dirty. This Idle valve, is the stepper motor unit (see top left, of second pic) that controls the idle speed, via metering the air to the intake, when the butterfly is closed. Its also the thing that makes that funny subdued cement mixer noise, when you turn the ignition on and off.
  4. When I refitted the TB, I filled the injector line with CRC cleaner too, so it would flush the injector, on first start up. Since I have done this TB clean up, my bike starts better, idles smoother and picks up more smoothly from lower engine revs, when riding. It has also reduced chain snatch, when riding a little too slow in a higher gear. jack #1977

Two Springs on the Throttle Body?

General Questions

Do I need an FI adjustment or Reset for High Altitude?

Is the BMS-C a "learning" fuel injection unit?

Do the F650 Fuel Injected models have an anti-knock sensor?

Strange Tach (RPM) behaviour?

Strange Tach (RPM) behaviour - buzzing?

FI bike keeps stalling?

How can I retrieve the fault codes / error codes?

Does anyone offer an alternative to the MoDiTeC?

How long does it take to update the software on a BMS-C?

Will my bike start if the battery is flat?

Tach needle does not return to 0rpm?

Does the BMW self correct for fuel mixtures like a vehicle does using the O2 sensor?

3 Identical 2-pin Connectors: Which goes where?

Potential Causes of FI Problems?

Difference between old and new Fuel Injector?