Actually I take that back. Try pspvdk_w. FR says it is "quotient: int.manif.pressure divided by pressure upstream of throttle valve"
Also, psspvdkb_w and psspvdk_w
ere's the code I found not complete vars tho, moved one.
seg020:CCAA sub_ACCAA: ; CODE XREF: interrupt_sub_B81C+CP
seg020:CCAA movbz r4, mste_wrong
seg020:CCAE mov [-r0], r4
seg020:CCB0 mov r12, rlfglmsm_w
seg020:CCB4 mov r13, umsrln_w
seg020:CCB8 mov r14, #2155h
seg020:CCBC calls 4, divide_sub
seg020:CCC0 mov r5, [r0+]
seg020:CCC2 sub r4, r5
seg020:CCC4 jmpr cc_NC, loc_ACCC8
seg020:CCC6 mov r4, #0
seg020:CCC8
seg020:CCC8 loc_ACCC8: ; CODE XREF: sub_ACCAA+1Aj
seg020:CCC8 mov word_302BCE, r4
seg020:CCCC mov r12, #6B62h ; WDKUGDN
seg020:CCD0 mov r13, nmot_word_3019A8
seg020:CCD4 calls 4, sub_41146
seg020:CCD8 mov wdkugd_w, r4
seg020:CCDC rets