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Tach Signal on Mitsubishi
The stock RPM meter has one wire towards ECU. I tried to tap it to one of injector channels, and added it to all h[0] masks. The gauge was working properly but there are two difficulites: * Right now I use all injector channels, so I don't have free inj channels anymore * No tach signal at deacceleration (decel fuel cut), so gauge shows 0 rpm at decel So I need a better solution. Of course I can solve it in many ways, but looking for a really nice solution... |
| old Tach Signal hack on this Mitsubishi |
| If you have free ignition FETs, use an ignition channel in the same way you used injector channel and added to h[0], only with ignition FETs. If there are no FETs left, wire ignition FETs together, with diodes seperating channels. One of the electrical engineers can help you better with this method, eg type and size of diode, etc. |
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The stock RPM meter has one wire towards ECU. I tried to tap it to one of injector channels, and added it to all h[0] masks. The gauge was working properly, with two issues:
* when no free injector output channels available * No tach signal at deacceleration (decel fuel cut => gauge shows 0 rpm at decel) ---- Configurable tach output can use any GenBoard/Manual/DigitalOut You can simply connect a free * injector output (or even the flybackless 2nd WBO2 heater output) * or p259 output * or stepper output * or ignition output without pullup to the RPM gauge. But the gauge might have some input signal requirements. Lacking a datasheet, often hard to know, but some careful experimentation is usually safe. Resistive pullup to +12V A 270 .. 2k4 resistor pullup (to +12V) can be tried (assuming they forgot it from the RPM gauge input). Not much risks here (any output can take 12V through 270 Ohm or higher limiting resistor without damage). Inductive pullup Since this involves more risks to the gauge (and to you : don't touch the signal, electric shock!), you might want to try the "resistive pullup" above. But if an RPM gauge originally got the input signal directly from the primary side of the ignition transformer, or you know the gauge needs high voltage to trigger, the above "resistive pullup" will not be enough for RPM signal. Than this inductive pullup is needed. Take a free ignition (not logiclevel, but IGBT) output (on Roland's ALS BMW 1.6 turbo we used EC36pin10, that is i259 channel 7 as seen on GenBoard/Manual/DigitalOut/Table), configure tach_channel and used an "inductive pullup" to 12V made from a [22 Ohm and 220uH] connected in series. |