Two Ways to Map an EFI?

By Dennis Santopietro

I have been told that there are two ways to map an EFI. One being to actually change the mapping of the ECU by getting a flash download. The other way is to use a piggy-back modem type device that allegedly alters the signals that are being received by the actual ECU. Provided that this is accurate information, can you please explain what the issues would be if a modem type device were to fail while on the road (i.e. would you cause engine damage if you were to unplug the device and ride home with the modifications still in place)?
  From Our Friends at DynoJet If a piggyback style system were to fail it is possible that your bike would not run until the unit was disconnected from the system. At this point whether or not your bike would run too lean while getting you home depends on your current setup. If we are talking about an exhaust and airbox then the bike would run too lean but not lean enough to cause any type of damage. Any modifications above this are hit or miss. Wrench Safe, FMH

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3 Responses to “Two Ways to Map an EFI?”

  1. Kendel-ra

    I loke

  2. Gypsy JR

    A Power-Commander type piggy back cannot do many of the things a flash of the ECU can do. The flash can change at what RPM the secondary butterflies open, and many other things, plus all the piggy back can do. But it takes a lot of work to create, test, verify, a flash. It has to be absolutely right.

  3. Paul

    I ride a 2003 Heritage and use a Vance and Hines Fuel Pak to allow me to swap exhausts depending on the ride (stock twin slip-ons or a V&H 2 into 1 big bore). On a recent 1200 mile trip around Ireland I had poor idle running with my stock slip-ons and rather than playing with the settings of the Fuel Pak, I simply removed it and the engine ran on the stock HD map in the engine computer. The Fuel Pak sits between the HD Engine management computer and the engine and adds to or subtracts from the HD computer output to provide a different real-time fuel delivery. What it relies on is a stock HD map, without which the Fuel Pak modified signals to the engine would be incorrect. Taking the Fuel pak out of the system completely, leaves you with the stock map. I believe most piggy-back devices do the same. So as the guys at DynoJet state, it depends on what modifications you have already made prior to fitting the piggy-back system. My Fuel Pak provides smoother power delivery when I have a V&H Big-Bore 2 into1 pipe fitted, but it will also run fine on the standard HD Fuel map. If you have made major changes to your air delivery, cam changes or other head mods, I would be cautious. However, if you have a young bike that's fitted with O2 sensors, then that would give you some protection as it manages fuel mixture through Oxygen monitoring in the exhaust flow and should reduce the chance of running too lean. A last note is that is that the fuel map modifications are normally within the piggy back device and you will need to remove it from the system as they normally sit between the HD engine computer and the engine fuel system. This took me about 10 minutes without any specialist tools with the V&H Fuel Pak. Hope this helps. ...wrench safe.