Remap guide for Tuning VP37 and VP44 Rotary Diesel Pumps, Diesel Tuning Guide, Remap Diesel, Bosch Injection Tuning, Diesel, Tuning Parts, ECU TUNING, Chip.
The VP37 can inject in a window of about 17-20° BTDC to about the same ATDC, however, if the resulting pressure maximum happens too late, efficiency will be much reduced. The main combustion event should have its maximal pressure about 5° ATDC (after top dead center) for best efficiency.
The 11mm plunger can be used to inject about 21% more fuel than the 10mm one – 21% more than 57mg/stroke is about 69mg/stroke. A 12mm plunger will be able to inject ~44% more than a 10mm one, or about 82mg/stroke.
Adjust smoke limiter, torque limiter, driver’s wish
Basically, there are 3 main limiters to determine IQ (injection quantity):
1) Smoke limiter – axes are air mass in mg/stroke and rpm, values are IQ in mg/str. 2) Torque limiter – axes are rpm and ambient air pressure in mbar, values are IQ in mg/str. 3) Driver’s wish – axes are pedal position in percent and rpm, values are IQ in mg/str.
The lowest of these values at any point is used.
As with a stage 1 remap
Adjust your fuelling and main limiters (DW/TL/SL), adjust SVBL and boost limiters, requested boost, N75, inverse driver’s wish if you’re using cruise control.
Take care to stay within your hardware’s limits – don’t run very long injection times without at least investing in an EGT probe to not kill your turbo or pistons with thermal overload to be able to react, at least. Also, a restrictive exhaust system will make things more difficult and raise EGT and back pressure, so consider upgrading yours, start with the down pipe. The stock down pipe is very restrictive and narrow; it has a sharp 90° bend right after the exhaust manifold outlet, which is not ideal.