absolute rail pressure = gauge rail pressure + BARO
MANVAC = BARO - MAP
DeltaMAP = absolute rail pressure - MAP = gauge rail pressure + MANVAC
gauge rail pressure is typically 400kPa (58psi).
I know this is an old thread, but
Here are some results of testing Holden's fitted with the E38 (all at altitude KOEO 84-85 kpa)
If the car is not fitted with an FSCM, INJPDELTA will not record below 400 KPA (irrespective if NA or boosted)
If the car is fitted with an FSCM but switched off in the ECM, INJPDELTA will not record below 400 KPA (irrespective if NA or boosted)
If the car is fitted with an FSCM and is enabled, INJPDELTA will record less than 400 when boosted. The INJ PW also increases compared to FSCM switched off. (INJPDELTA now less than 400)
When in boost, INJPDELTA does not follow the calculation posted earlier. (still trying to understand why)
Some examples of logging
MAP INJPDELTA_DMA kPa kPa 84 415.6 84 415.6 84 415.6 84 415.6 84 415.6 84 415.6 84 415.6
MAP INJPDELTA_DMA kPa kPa
164 375 167 380 175 383 190 381 195 368 199 365 198 351 195 330 191 355 194 352 198 354
2011 VE SSV 419 + CAM + Whipple 2.9FF SC + PPV front struts + Bilstein rear shocks + 6L90E with single piece carbon fiber prop
Good question... it seems the ECM has knowledge and/or control of the pressure produced by the FSCM, so the above math relationships are broken.
It makes some sense when you compare the injector flow base of non FSCM and FSCM equipped cars
FSCM cars have a fuel pressure sensor and the IFB caters for boost, which the non FSM do not
NON FSCM (flat line from 400) sq root
LABELS Injector Flow Base (Grams/Second)
Delta MAP kPa Value
128 5.337646
144 5.337646
160 5.337646
176 5.337646
192 5.337646
208 5.337646
224 5.337646
240 5.337646
256 5.337646
272 5.337646
288 5.337646
304 5.337646
320 5.337646
336 5.337646
352 5.337646
368 5.337646
384 5.337646
400 5.337646
416 5.478027
432 5.615112
448 5.748779
464 5.879394
480 6.007446
496 6.007446
512 6.007446
528 6.007446
544 6.007446
560 6.007446
576 6.007446
592 6.007446
608 6.007446
624 6.007446
640 6.007446
FSCM (slope)
LABELS Injector Flow Base (Grams/Second)
Delta MAP kPa Value
128 2.974609
148 3.198486
168 3.407959
188 3.604980
208 3.791992
228 3.969970
248 4.140625
268 4.304199
288 4.461914
308 4.614257
328 4.761718
348 4.904785
368 5.043701
388 5.178955
408 5.310790
428 5.439453
448 5.564941
468 5.687988
488 5.808105
508 5.926025
528 6.041503
548 6.154785
568 6.266113
588 6.375488
608 6.483154
628 6.588867
648 6.692870
668 6.795409
688 6.896484
708 6.995849
728 7.093993
748 7.190917
768 7.286376
2011 VE SSV 419 + CAM + Whipple 2.9FF SC + PPV front struts + Bilstein rear shocks + 6L90E with single piece carbon fiber prop