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Discussion Starter #1
Hello! I am thinking of getting another bike mainly prompted by the fact that working on my Desert Sled is so complicated with 'special tool required' for everything. I read many times in forums about other makes of 'no need to remap, just let the ECU autotune' I also read that since 2015 all new bikes and cars have to feature an auto tune capability. The procedure involves a reset by letting the machine idle for quite a long time - 10 to 12 minutes. I never hear it mentioned on this forum though, anybody any feedback as to why? Thanks
 

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Most modern ECUs autotune for minor changes to the motor or environment. However, the manufacturer does not program the ECU to autotune for large, unexpected changes, such as adding a cam with a new profile, or a full exhaust, or removing the catalytic converter, or opening up the airbox, or removing the SAI system, or removing the O2 sensors. You will need to remap the ECU if you make major changes to the motorcycle.

It is analogous to a home builder not putting in 15-foot tall doorways because he/she didn't expect people that tall would live there. If 15-foot tall people want to live there, they have to modify the doorways. The standard doorways can accommodate 4, 5, or 6-foot tall people, but not major changes like 15-foot tall people.

I would not listen to anyone who says you can make major changes to a motorcycle and let the ECU autotune. These machines already run very lean (to pass emissions), and most of the changes we make cause them to run even leaner.

-0260
 

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Thanks for this....I have been watching Tec Parts on Youtube who indeed de-cat, change cams, air filters and exhausts on Triumph and RE and then seem to claim that forcing an ECU reset seems to do the job so maybe different manufacturers build different tollerances into their auto tune capability. I have heard people claiming that BMW tune within quite wide tolerances too. I do miss the days then you could just change a jet and know where you were.
 

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Seeing as most FI and engine management systems are make by one or two companies with Bosch being the major player they are all essentially the same. There is no reason why for the average user an auto retune is not a valid option to at least try before shelling out money that might not be required. It is not going to do any harm.
The hard part is doing the auto tune properly the bike has to be stone cold when started (leave it off for 8-10 hours to be safe) and you cannot even touch the throttle during the initial warm up. Resist the urge to give the bike a rev.
 

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Injection system tune all the time actually, by filling the short and long term trim tables. To compensate for variables in air pressure, airfilter clogging, etc. They are programmed to “know” what the engine requires at closed loop and adjust accordingly so it can correct open loop operation.

As far as I know all the “15 minutes idle” does is clear those trim tables, so it can start all over again (effectively filling the short term trim tables only). Information that can be very useful for a fuel injection engineer.

It does not correct for major changes in exhaust flow if you installed a different header or removed the cat/resonator.
 

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The closed-loop, narrowband setup of the scrambler is not going to be able to adjust the fuel enough to compensate for major changes such as a de-cat aftermarket exhaust, which is why manufacturers such as Termignoni sell you a remap for the bike with their de-cat exhaust. That is why I have the Rexxer on my scrambler, which disables the O2 sensors (puts it into open-loop), disables the SAI system, and replaces the fuel map in the ECU to compensate for the full exhaust, modified airbox, and filter. If I would have made those mods and left the stock ECU in place to compensate, I would destroy the motor (probably burn valves) by running way lean. There are plenty of open/closed loop articles out there if someone wants to learn. I modified my Grom as well (and added a Yosh stage one cam in addition to airbox and exhaust mods) and had the ECU flashed to compensate.

You need a wideband sensor and ECU with wide mapping capabilities (like ARacer kits) to compensate for major changes, such as full exhausts. Stock ECUs and narrowband sensors are not going to cut it, even if the Internet says they will. :rolleyes:

Correction: You need a wideband sensor if you want to autotune the full range of throttle. You don't need one if you manually remap (flash) your ECU.

-0260
 
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