I have a homemade 3D printer setup and working with one exception. The extruder steps per unit does not seem to work ccorrectly. This particular extruder needs that to be set to 400, but no matter what I set it at, extruding 100 mm results in extruding about 150 mm of filament. I set it to 100 and it still extruded 150 mm.

I am using Arduino 1.8.9
Marlin 1.9 tweaked for Robo 3d

Here are the relevant settings.
Any thoughts on why the extruder setting may not be working when I was able to successfully change the Z setting to 400. .

/** * Default Axis Steps Per Unit (steps/mm)
* Override with M92
* X, Y, Z, E0 [, E1[, E2[, E3[, E4]]]]
* ROBO z steps per version
* ----------------------------------------
* R1/Beta 5/16" threaded rod = 2267.72
* R1 8mm threaded rod = 2560
* R1 alt upgrade TR8*2 leadscrew = 1600
* R1+/R1 Official upgrade TR8*4 leadscrew = 800
* R1 alt upgrade TR8*8 leadscrew = 400
*/
//#define DEFAULT_AXIS_STEPS_PER_UNIT {80, 80, 2560, 400}
#define DEFAULT_AXIS_STEPS_PER_UNIT {80, 80, 400, 400 }
//--ROBO-BH Default steps per unit for RoboR1+PLUS
/**
* Default Max Feed Rate (mm/s)
* Override with M203
* X, Y, Z, E0 [, E1[, E2[, E3[, E4]]]]
*/
//#define DEFAULT_MAX_FEEDRATE { 500, 500, 5, 25 }
#define DEFAULT_MAX_FEEDRATE { 550, 550, 20, 30 }
//--ROBO-BH (mm/sec)


/**
* Default Max Acceleration (change/s) change = mm/s
* (Maximum start speed for accelerated moves)
* Override with M201
* X, Y, Z, E0 [, E1[, E2[, E3[, E4]]]]
*/
//#define DEFAULT_MAX_ACCELERATION {900, 900, 300, 10000}
#define DEFAULT_MAX_ACCELERATION {1000, 1000, 300, 11000}
//--ROBO-BH (mm/sec)


/**