This is my wife's daily driver, '83 Porsche 924 with 2.0 liter inline four. It had nasty K-Jetronic and transistorized ignition before, I made EFI conversion to it.
14.08.2007: Car has IHI KHF5 turbo installed since winter. Also an intercooler from Porsche 944 Turbo, 440cc Low-Z Denso injectors, oil cooler from Opel Senator and all cutsom pipe-work. Boost is 0.92 bar and compression ratio is stock 9.3:1 and engine is running strong and reliably. Using passive wasted spark coils from Lancia Delta Integrale.
Since last week I uploaded 1.0.73 firmware with 16x14 tables. Car seems to be running smoother on lower (1600-2200) rpms. Could be because of the better resolution of this firmware?
Main problem is that I can't the coils to work ok using i259 logic outputs. Today I downloaded experimental new MT+ 1.1.0 firmware and uploaded it to VEMS and configured it to use stepper outputs, but I did not get the engine to fire. Could someone (Marcell?) review my config+tables ( MembersPage/PeepPaadam/PorscheNineTwoFour/Config ) and note if there's some mistake or other obvious thing that I've overlooked?
So, no workie with stepper outputs, so I unsoldered 511 Ohm resistors from logic-level outputs and used 200 Ohm ones instead.
I got the car running ok.
Inductive pullup is needed to get this tach working.
Connect the 22 Ohm resistor and 220 uH (not milliHenry, but microHenry!) inductor in series, and connect this (direction is irrelevant) between the IGBT output and +12V (as an inductive "pullup").
This way the IGBT output can drive the old-type tach input , as the voltage will jump to 380V immediately (but only for a very short time) after the IGBT is turned off. Make sure it's protected well (with insulation), it can kill someone.