KTM 690 - Stalling and throttle issues

A lot of 690 owners complain about stalling and/or a jerky throttle response. While there are differences between individual bikes (and their owners...), there seems to be no pattern in models or production years. Some bikes suffer more from stalling and throttle glitches than others. Most don't at all or only occassionally. But these niggles are usually easy to solve!

The fact that KTM 690s are a bit more sensitive to stalling and/or throttle issues is down to two important factors; performance and emission & noise regs. The 690 is BY FAR  the strongest 4-stroke single on the market today. This means a relatively high state of tune, big valves, big ports, big throttle body, high compression, low rotating mass etc. The graph below is from the German bike mag 'Motorrad' and shows just how strong the 690 is compared to its 'rivals'. There is no comparison with any other single.

But the 690 also has to meet the ever tougher regulations for emissions and noise. Power & performance do not go hand-in-hand with noise & emissions regs very well. Especially not with a big single. The Lambda sensor controlled EFI keeps the engine on a super-lean mixture, catalic converter(s), Secondary Air System, throttle restriction in 2nd & 3rd gear are all there to make it pass the murdering emission & noise regs. They do not help the engine... they do exactly the opposite. The high performance concept & design of the 690s combined with all the environmental measures makes them more sensitive to the right setup and adjustments.

But we all want that performance so stop moaning and deal with it properly. 95% of the stalling and throttle issues are easily solved and are usually only down to proper service and dealer knowledge. This are the steps to follow to kill throttle gremlins:

  1. Throttle calibration (you)
  2. Idle reset procedure (you)
  3. Throttle sensor check/adjustment (dealer)
  4. Idle CO check/adjustment (dealer)

1. Throttle calibration

The simplest one. This re-calibrates the start & stop position of the throttle grip. Turn the ignition on but don't start. Wait for the tacho needle to return to zero. Then turn the throttle grip gradually from close to open and back from open to closed. Don't let it snap shut. Turn the ignition off, done.

2. Idle reset procedure

The 'famous' 15 minute idle reset procedure. This resets the adaptive base values of the ECU. It won't transform the bike but it can make a worthwhile improvement. It is very important that the engine is stone cold. One or two hours after riding is not enough! Do this after the bike has been off for a full night or day. Start the engine and let it idle for 15 minutes without touching anything. After 15 minutes, switch the engine off with the ignition key. Done. During this procedure you won't see or hear anything happening besides the idling and (probably) the fan. Don't worry, the reset is done. Besides after certain maintenance or parts replacement, you could consider doing it twice a year with the turning of the seasons. A reset for the colder autumn & winter period and one time for warmer conditions during spring & summer. This is not mandatory or needed and don't expect miracles.

3. Throttle sensor check/adjustment

This is a dealer only job. But an important one. It requires a KTM diagnostics tool hooked up to the bike. There are two throttle sensors on the throttle body (where the carb used to be...). On the left hand side is the sensor controlled by the ECU. This one is used when the ECU takes over the control of the throttle valve from the rider (ride by wire with data from the throttle map). On the right hand side is the sensor connected to the throttle cables coming from the throttle grip. This is the one that makes you think you're in control. :-) Both sensors interact with each other and each has its own base adjustment. It's not difficult to understand that these are important. The abbreviations in the maintenace & repair manual for these base adjustments are 'THAD' and 'APAD'. The procedure is pretty straightforward but precise. It shouldn't take longer than 20 minutes or so. After adjustment it makes sense to do step 1.

4. Idle & Load CO check/adjustment

This is also a dealer only job. It can only be done if the dealer has the latest XC-1 diagnostic box from KTM. The XC-1 gives the dealer some control over the idle & load mixture through adjustment of the CO targets from the ECU. This is within a limited bandwith but enough to iron out idle or fueling glitches. Adjustments are made by up & down mouse-clicks with realtime bar graphs on the screen that show what happens. Very easy. Only small changes at a time should be made. The effect of changes to the idle CO take a while to show in the graphs. The target for load CO (riding) is usually set at 1.000. This is Lamda 1 and corresponds to an air/fuel mixture of 1:14.7. Adjustment of this value goes in small steps of 0.008 but has a clear effect on the mixture throughout the rev range. Only one or two steps is enough. Not more 'cos the mixture is likely to become too rich or lean. So if the mixture needs to be a little richer (probably) this would be 1.008 or 1.016. Ideally this should be done on a dyno but minor adjustments like this can be done by 'set & ride' too.

After these 4 steps, 99% of all idle and throttle glitches will be solved. Most already after steps 1 to 3. If not, something else is really wrong or malfunctioning but this is rarely the case. If so, there is a big chance the cause will show up during diags in the error message log too.

About 690 EFI mappings

KTM 690 models all have the same Keihin EFI system. This EFI system is different in a number of ways than on most - if not all - other bikes. It uses a 46mm single valve throttle body with two ECUs. One controling the fueling & ignition and the other controling the throttle valve through semi ride-by-wire. The ECUs interact with each other communicating over a CAN-BUS connection (CAN-H & CAN-L in the drawing). The two cables from the throttle grip hook up to the throttle valve but the ECU has the ability to 'take over' if needed. Closing the throttle valve is 'hard wired' for safety reasons. Under normal conditions the throttle valve will follow the commands from the rider 1:1. But if the throttle commands get outside the working parameters of the engine, the ECU will take over controlling the throttle valve in a way that the engine will keep performing optimal. For instance; wacking the throttle wide open in a split second at 2500 RPM in 5th gear will normally stall the engine. This is when the throttle ECU takes over and opens the throttle as quickly as the engine will allow without stalling. A neat and sophisticated system that works really well. The fact that you never feel the ECU taking over when riding a 690 kinda shows how good it works.

Because of the setup with two ECUs the 'mapping' or 'fuel map' for a 690 also consists of two parts/files. A map (file) for the fueling: ....FI.BLZ and a file for the throttle: ....EP.BLZ. This has led to problems and confusion with both dealers and owners. The two parts of a fuel map belong together and are NOT interchangeable with other fuel maps. When updating or changing the fuel map it is critical that both files are downloaded to the bikes' ECUs.

In a drawing it all looks fairly simple but there's a lot going on here:

Last modified: 07-09-2009