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Tuesday, July 26, 2022

Mass Flow Through the Throttle Body

 After you have tuned the VE and the IPW Comp table, there is one additional fuel table that you can correct.  This table is called the Mass Flow Through the Throttle Body and is found in the Airflow folder in C3 module.

Mass Flow Through the Throttle Body Table

    (Click on image to expand)

The following procedure is one I use, however I typically have wideband sensors installed and use a modified python equation to tune it.  With only narrowband sensors, more care will be required to tune this table.

NOTE

The Mass Flow Through the Throttle Body is an Alpha-N mode table.  This means it is the fuel table used if the MAP sensor fails.  It is also used during startup, warmup, and certain rapid throttle transitions before the MAP sensor has time to respond.  Tuning when not on a dyno is certainly a harder procedure and extra care needs to be exercised.  The engine might stall on you and you must be ready for this.


You will need to prepare your tune by failing the MAP sensor to activate the Alpha-N mode.  The MAP sensor is failed manually by setting the Max MAP Voltage to .249.  This is found under the Sensor/MAP Sensors Folder in C3.  Once you fail the MAP sensor by inserting this value into the Max Map Voltage cell, you will have an Engine Light on when flashed to the ECU.  This is normal and expected!

Failing the MAP Sensor

(Click on image to expand)

Once you have made this setting, save the tune (be sure to make a notation in the Notes section of the tune that you have failed the MAP sensor). You should name this tune something that will remind you that the MAP is failed, i.e. "Vxx-MAP.djt" where xx is your current version.  This tune should only be used while tuning the Mass Flow Through the Throttle Body and never for normal riding.

Once you flash this to your bike, you need to do a start-up with a complete warmup of 5 minutes while the bike idles.  Use a fan if necessary to keep your engine cooled.  Do not overheat your engine!  Be sure to set one of your display panel to Engine Temp to monitor this temperature.

Once you have warmed up the engine for 5 minutes to ensure the enrichment mode is off, start the logging on the PV3.  Let it idle for 30 seconds and then very slowly ramp up the idle to 3k and then slowly ramp it back down.  This should be done over 30 seconds or so.  Stop recording to save the log.

Turn the bike off and let it cool.  Copy over the log created over to your computer and load in the tune in C3 and open the log in the Data Center.  While in C3, locate and open the equation "Indian Universal MF_NB.py".

Run the equation, which will correct the Mass Flow Through the Throttle Body table.  This table is equivalent to the VE table, the only difference is one is used in an Alpha-N fuel injection system and the other in a Speed Density fuel injection system.  Refer to my post on Fuel Injection System Overview if you want more information on this.

Once you have corrected the tune, save it with a new version and flash it to the bike.  Note, you can restore your Target AFR to normal values or keep it expanded. Your MAP sensor is still failed as we need to address tuning more areas of this table.  Start up the bike and verify the engine is running okay.  If so, let it warm-up for a minute or so and very carefully go out for a ride.  You should pick a ride that has very little traffic and no challenging traffic situations.  You need to be careful that the engine could stall at anytime.

Once you ride for at least 5 minutes start recording your log(s).  Ride by varying the RPM and Throttle.  I recommend on this first run to keep it under 3k RPM.  Once you have recorded for 1/2 hour or so, stop the recording on the PV3 and verify it has saved the log, then you can safely turn off your engine.  Copy over the log(s) to your computer and perform another correction with the "Indian Universal MF_NB.py" equation.  Save the new tune and flash it to your ECU.  Repeat until you feel the engine is running okay.  Note, it will not run perfect, but should run okay.  If the idle through 3k is running well, you can decide if you want to expand the Target AFR and hit some higher RPM/Throttle positions.

NOTE
Because we are in Alpha-N mode, load has nothing to do with engine operation.  It is strictly a Throttle position and RPM based system.  The ECU will not protect the engine due to excessive load so care needs to be taken while tuning.  The ECU will be correcting the fuel based on the o2 sensors, give it time to make these corrections and simply do not slam open the throttle.  You can go to wide open throttle, but do it slowly to allow the ECU the time it needs to make fuel corrections.  If at any time the engine is bogging down, back off of the throttle.  You will need to make corrections to the current tune and build up to the WOT on future tunes.

Once you are satisfied with the corrections made be sure to restore the Max MAP Voltage to its stock value and save the tune.  You can continue tuning your engine in the standard Speed Density mode using the VE & IPW Comp tuning equation.