How to select the right Super Tuner map for your Harley
As an instructor of Harley, EFI calibration with Super Tuner one of the most common mistakes I see people make is selecting the wrong calibration/map file. Unlike piggy back boxes (i.e. Power Commander), Flash tuning products base cals can be very different from each other. There are things, hundreds of little things, in the background of every Map/Calibration that make it critical you select the correct one for your motorcycle. One of the more critical things in the background of a base cal is when the MAP (Manifold Air Pressure) sensor is read. It is programmed into the background based on cam timing and reversion pulse (pressure wave) which travels through the intake. Besides determining engine load, this is how the ECM determines outside air pressure which, combined with the IAT (Intake Air Temp) sensor, is used to determine the air density. It’s basically how the ECM knows how much oxygen is in the air. It uses this information to correct the fuel mixture for air condition fluctuations – temp, pressure, humidity – caused by weather and altitude changes.
If the MAP read is off, even if you calibrate your VE tables on a Dyno when the weather changes, the way the bike runs will change as well.
We will discuss proper calibration of the ECM in the future, but for now you should understand that the goal of using a flash tuner is to calibrate the air tables (VE tables) in the ECM to match the air flow through your engine. The actual “tuning” is done after.
Back to selecting a base Cal/map. We select a map for the the things we can’t change.
Here is the list – in the order of importance – we use to pick a base calibration to start with it.
- Cam profile
- Intake open degrees (IO)
- Exhaust close degrees (EC)
- Exhaust System
For choosing a base map/cal, things you can change like Cubic Inches, Injector Size do not matter. You can change them to match your bike.
Year and model I think is pretty self explanatory.
The cam timing has a big effect on the timing of the pressure wave in the intake manifold. Especially the IO and EC. If you understand cam timing events, you may know that IO and EC determine valve overlap. It is critical you understand that the total degrees of overlap is not what we are looking at here. It is when the overlap occurs during the crankshaft rotation that matters for map selection.
pick a base map for a Screamin Eagle cam that has the same or as close as you can find Intake open degrees and exhaust closing degrees.
The exhaust can affect the timing of the pressure wave as well. However, Screamin Eagle doesn’t give you many choices as far as exhaust systems. If you find there are a couple of maps that match #1 & #2, and the one you try doesn’t seem to work so well, you can try one of the others. If you find it does work, make sure you save the exhaust info with its notes, so you can use it in a future bike with a similar set-up.
After you select your base cal/map, you set it up for your motorcycle.
- Cubic Inches (a good rule is to set this at 1.1xHP as a start point)
- Injector size
- If you have VE tables from a map for a bike with similar cams/exhaust/heads… you can paste them into your base map
- We also would modify or copy and paste ignition tables here if required.
You can set up a MAP gauge in Super Tuner to help see if the base cal MAP read is close. It i should idle at 25-35 kpa and under a 100% throttle run the manifold pressure should match the air pressure in the room. I read the room pressure off the Dynojet Dyno. At sea level it should be close to 100 kpa. at higher elevations it should be less. Ambient air pressure will change some with the weather.
At this point if possible, we would flatten the Air Fuel Table put the bike on a Dyno and dial in the VE tables. We will discuss that more in a future post. as well as setting up the tune: air fuel table and closed loop.
Until next time.