ECU re-map or install Piggy back unit?

What can you expect from a RexXer re-map?

Optimal drivability
RexXer performance maps eliminates the annoying drivability issues such as surging, delayed throttle response or flat spots caused by the tree hugging maps manufacturers are required to install in their bikes at the factory to meet Euro 3 emissions and noise restrictions. So now your bike can operate like the design engineers wanted it to. (RexXer maps are sometimes developed in close relationship with some of the manufacturers original design engineers)

Maximum power
No matter what modifications you‘ve made, without the adjustments to the engine management system to match the new components; i.e. performance exhaust, air filter, camshafts etc., the desired power increase will never be met and the performance potential will be lost without the RexXer Tuning map to match your components

If this was so easy to achieve why is are bikes so sub optimally mapped off the show room floor
Better driveability and more power are in fact very simple goals to achieve and the factory technicians could easily program your ECU to achieve the same results, except they are not allowed to. Bikes must meet the new Euro 3 noise and emissions constraints, which are very much in conflict with your goals for you bike. Under these parameters your bike runs very lean, which means it has difficulty setting fire to a lean inlet charge and the bike surges and does not run as smoothly as it could. Running lean also makes your bike run hotter than it should but it does reduce the emissions. However because running lean limits the performance efficiency of your bike your fuel economy also often suffers.

Should I get my ECU re-mapped or install a piggy back unit such as a Power Commander?

How does each option work?
This is a generic discussion. There are many brands of piggy back units on the market that offer different features and different levels of sophistication but they are all constrained by the way they must operate with your bikes ECU.

  • A Piggy back unit can only alter or offset the input signals to the ECU or interfere with its output signals or both.
  • Remapping the ECU allows you to change the logic and goals of the ECU which a piggy back unit cannot do. So what’s the advantage of this?

What are the advantages of remapping your ECU?
The decisions your ECU makes are not static. Any changes to temperature atmospheric and fuelling conditions are adjusted for by your ECUs logic. Each paramater that influences your effects your ECUs decisions is known as a channel, there may be as 30 different channels in your ECUs porogramming. Your ECU is able to look at a wider range of your bikes sensors than a piggy back unit and this is one of the key advantages of re-mapping an ECU rather than using a near deaf, dumb and blind (by comparison) piggy back unit. It is why all top race teams will use an upgraded ECU rather than a piggy back unit where the rules allow an upgraded ECU. No MotoGP bike uses a piggy back unit. Doing it natively through a performance ECU which can 'listen' directly to all your bikes sensors is a superior solution.

When you re-map the bikes ECU it still carries out continuous adjustments to fuelling and ignition, etc based on feedback from its myriad of sensors (just like it did before you altered the map - but now according to the new performance focus instead of an economy/emissions focus).

Your bikes sensors and the ECU logic allow the bike to tune itself continuously within quite a wide range to always try to obtain the ideal performance AFR within a wide range of atmospheric and load conditionsc and even cope better than most people realise to changes of exhaust systems. In fact it can do this perfectly well before being mapped except that it was always readjusting parameters to maximise performance within the  Euro 3 emissions and within legal presribed noise requirements, both of which are very constraining!

With a re-map your ECU will now:

Optimise fuel injection timing and quantity for increased smoothness, throttle response and performance.

Optimise ignition timing for increased smoothness, throttle response and performance.

Re-mapping your bike does not require you to install extra hardware/electronic on your bike or tap into your bikes wiring loom. Less to go wrong and less time to install.

You can reflash the ECU multiple times if your performance intent or requirements change.

You can reflash your original map back into your ECU. (time to do this on a Paniglale is 15 minutes plus 30 minutes to reconnect lambda sensors.

And of course before re-mapping your bike the RexXer agent will always read and backup your bikes original mapping

There is no externally visible structural changes to the bike, you don’t need to remove any hardware from your bike before taking it to get serviced - even workshop tester does not recognize it! – Although we always recommend that you advise your service agent not to update or overwrite your ECU map as part of their service. In fact some Ducati service agents now have RexXer remapping equipment in-house.

....and of course remapping your ECU at $449 is much cheaper than installing a piggy back unit.

Quick summary of some of the other features of a RexXer re map that can be achieved.

  • Carbon Monoxide. Air Fuel Ratio trimming (This is only necessary on some models of ECU).
  • Optimise fuel injector sequencing to ensure that you get the best fuel air mixing in the inlet runners.
  • The oxygen sensor parameters can be adjusted, or lambda control can be disabled below 4000 rpm in software without causing error codes.
  • If fitted on your bike (e.g. Ducati Panigales) noise limiting valves in the exhausts on  can be disabled to increase performance and improve exhaust tone.
  • Immobilizer can be deactivated (Ducati only) - used ECU’s can be re-used. Operation without a factory dashboard can also be configured.
  • Read and Clear error codes.
  • Reset Service Due light.
  • TPS (Throttle Position Reset) generally required after re-mapping your ECU
  • APS reset.
  • Reset auto-adaptive parameters.

Disadvantages of a Piggy Back unit
A Piggy back unit can only alter or offset the input signals to the ECU or interfere with its output signals or both.

Consequently there’s a number of things Piggyback units can’t do....

Most piggy back units can only alter fuelling. A couple can also alter timing. e.g. the Rapidbike Racing unit which is probably now the most sophisticated of the piggy back units can advance or retard timing 10 degrees but I am not sure if this is manually done or automatically done and if it is automatically done what logic/sensors are used to determine advance or retard?

Unlike an ECU re-map, most piggy back units can't disable the exhaust valves. Many bikes now, like the Ducati Panigales have exhaust valves that cut noise (and unfortunately a smidgen of power) at lower revs to help the bike pass European noise tests.

Unlike and ECU re-map most piggy back units can't effect your secondary air injection valve system. Reprogramming your ECU can allow you to turn off the secondary air injection system to gain power and improve smoothness.

Unlike and ECU re-map most piggy back units can't alter your rev limit. Actually some can but because a standard ECU is only mapped to say 12000 rpm when you use a piggy back unit to extend the revs say to 12500 rpm the extra 500 rpm have to run on a static fuel and timing map that isn’t altered by what the ECU sensors tell it about the running conditions in the normal way. By extending the rpm limit in the ECU you can use all the dynamic control features of the ECU to change the fuelling, and ignition depending on running conditions and so you get a full dynamic map right across the rev range including the extended rpm range.

Because piggy back units operate by interfering with the output signal of the ECU to the injectors to alter the fuelling they are always one step behind the ECU. They don't operate in real time (they are slower to react to than a re-mapped ECUs and often have to try and counter react to a change the ECU has made after the ECU has made it.

They can't change your AFR fuelling below 4000 rpm because they end up in an argument with your lambda sensor and ECU when they attempt to do it. The Rapidbike piggy back unit is one notable exception to this because it seems that it also connects between the bikes lambda sensors and the ECU as well as between the ECU and the injectors. This means unlike other piggy back unit we have encountered, it can trick the bikes input to the ECU from the lambda sensor so that the ECU doesn’t just try to correct the changes jut made by the piggy back unit driving the fuel injectors. Not surprisingly many piggy back units advise you to first disable the lambda sensors with an ECU re-map (or some other eternal means that won’t bring up error codes in your bikes ECU) so that they the piggy back unit can provide improvement to the running of your bike under 4000 rpm.

And of course a Piggy back unit can't change any of the logic decisions your ECU makes with regard to fuelling and ignition timing, temperature, barometric air pressure, etc. simply because they simply don’t know and can’t change what the sensors are telling the ECU.

With time and effort you can remove them before taking your bike for a warranty service, but they may cause error codes to show up and still be present in your ECU even after you have removed them.

Advantages of piggy back system?
Some piggy back units can provide:

  • A pit lane speed limiter function
  • Launch control. 
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