Throttlebody Mods and Tune

[barbagris]

But yet another avenue for research and maybe a little development..

So a bit of fiddling and I have it down to 40°C - ambient close to 34°C.

 

[Speedy]

MAP based tuning uses absolute pressures. Thus, altitude has minimal impact (wave pulse tuning in the intake and exhaust do change some with decreased density with the greatest impact at WOT.) For example, to run at 50 mph on level ground or to accelerate at any given G rate takes X amount of power no matter which gear you are in or the altitude you are operating at (not counting the change in wind resistance.) If you are at higher altitude, you simply open the throttle further to achieve that power than you would at sea level. Both low and high altitude require the same absolute manifold pressure to achieve the same power (discounting the above changes in pulse tuning.)

You can run entirely on MAP tuning any where from sea level and up without any altitude compensation from a second air pressure sensor. I would suggest that the more one rides in quickly varying altitudes the greater the need for MAP tuning. Personally, I would have the change over from L-table to F-table set above 60% TB opening at the very least.

Attach an absolute pressure gauge to a TB port, ride or load on a dyno and correlate manifold pressure, load and rpm. F-table tuning is easier because you can run at 10 to 100% throttle openings at a constant load for each and interpolate in between. Not so easy with MAP values as you need variable loading.

Secondary air pressure sensors are essential for F-table tuning to work at various altitudes. Both fixed and load based operation need accurate and fast intake air temperature sensors (Ideal gas law.)

 

[barbagris]

Both low and high altitude require the same absolute manifold pressure to achieve the same power (discounting the above changes in pulse tuning.)

Thank you maestro. Van der Waals was playing on my mind a bit. I shall KISS and follow Ocham.

 

[Kevin frazier]

After I have done bored throttle bodies, if this is any help, take the linkage off the stepper motor and set the idle with the screw. Match the idle set speed in your tune with tuneboy/tune ecu and remember what is was like in the old days. Just warm the engine for maybe 40-60 seconds until it will idle. ALL GOOD. No electrical genius needed. NO fault codes, no hair pulling etc etc. Good luck.

Got it! And no stepper motor, no tps, and no 2nd throttle shafts,