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= TVR Regeneration = I have 'misplaced' a few parts of the car over the last few years. One of them happens to be it's original VEMS. (It's now doing service in another of my cars...) I have some parts of an old VEMS where the main board is beyond repair, so my cunning plan is to purchase a new v3.8 main board and build up an ECU using the spare case and other parts. I note that a few changes have happened in the last few years so I will sketch out a plan and include some questions to make sure I've got all the changes covered. == Outputs == === Flyback considerations === ''30v flyback rail is the fastest available for highZ injectors'' so this will be used. ''For outputs controlled by injector FET which do not benefit from heightened flyrail, like: IAC, boost control valves etc. mounting a local flyback diode across the solenoid connector is recommended.'' This isn't a problem for the TVR because it uses all 8 channels for injection. It is tempting to increase the flyback voltage and use IGBT drivers (instead of FETs) to close the injectors faster, but it would seem that this is not recommended. === P259 Output Resilliance === Q: Has the resilliance of the P259 been improved? I had one or two problems with it in the past (usually my fault!) A: ''p259 outputs have been outfitted with additional on board flyback diodes, this does not help against over-current or ground/powerground connection problems but its does make it more resilient against flyback spikes'' I will plan to use the 4 additional NFET option from ''https://shop.vems.hu/catalog/vems-p-48.html extra NFETS'' to drive relays or coils so as to better protect the P259 from things like excessive inrush current demands. Q: Are the additional FETs implemented as a daughterboard arrangement? Is there more information for this option - such as which pins on the EC connectors are used and which outputs can be rerouted? Thinking that it might affect analog inputs - if this is the case I will make an external driver box to protect the P259. === Fuelling Outputs === * 8 large Siemens injectors driven from the 8 injector outputs. I used to use IGBTs for these because they proved more reliable. * Additional NFET output #1 (reuses a P259 output?) to drive the fuel pump relay. * 2 Wideband lambda sensors, connected with decent shielded cable, apart from the power. They will be LSU4.2 because I have a box of these to use up! * Evaporative emissions control valve. Driven from Additional NFET output #2 (reuses a P259 output?) to protect P259 chip. This will use a secondary PWM control. I haven't used this on VEMS yet, because it is relatively new (since 2014) but how hard can it be? === Ignition Outputs === * 8 Coil-near-plug ignition channels driven from the 8 IGBT outputs. I have both crank and cam sensors so can use them as fully sequential ignition. It looks like nothing much has changed here, and this bit always worked well. === Idle control Outputs === * I have retained the standard 4 pin stepper motor. This is driven using the stepper outputs on the EC18 connector. I see no need to change this. === Misc Outputs === * 2 cooling fans on separate outputs so that they can react to different temperatures. Additional NFET outputs #3 and #4 (reuses a P259 output?) drive relays for these. * Tacho output on P259. * Shift lamp currently on P259, but may be replaced by more intelligent instruments. * Check engine / Fault lamp === Summary of Outputs === It would appear I've used all the available outputs on the EC18 and EC36 connectors and still might have one feature that can't be realised. So I need to decide between shift lamp or fault lamp. (It's a TVR, so it will probably need to be the fault lamp!) I would strongly prefer that outputs are all driven through the EC36 and EC18 connectors with minimum external components. == Inputs == === Sensor Inputs === * All the usual sensors from the EC36 connector are unchanged as far as I can see. There are some minor changes in triggering, but nothing more than resistor values. * For reference the crank trigger is a VR 36-1 tooth wheel and the cam is a hall based single hole wheel mounted on the cam pulley. Both have been shown to work robustly in the past. * One channel of knock sensing. (Two would be nice, but so far it seems a little unnecessary) Q: This was always connected as a "green wire". The v3.8 board looks like it has dedicated tracks. However, Knock #1 now conflicts with WBO2 #2 Nernst cell on EC18 pin #1. Is this correct? My choice would therefore appear to be to use knock #2 as the main sensor input and limit myself to one sensor, or bring the two sensors out on a separate connector mounted on one of the case ends. The former keeps the wiring simple, but the latter frees an EC18 pin to be a spare analog input, and these are always useful - see later. * Fuel temperature. A useful input to detect heat soak! The car had this from new, so it seems only fair to keep using it on an "anytrim" input. It is to be connected to an analog input on EC18 pin #3. * Wheel speed input. Again I would like to get at least one speed input into the ECU. Q: This is on EC18 pin#8 and conflicts with the WBO2 #2 pump + signal. Is there an alternative pin (for either function) that doesn't require too much rework? Q: Additionally, is the second wheel speed input tracked to a particular EC18 pin? If I want two wheel speed inputs then it might make more sense to output them on another separate connector. * Oil pressure input - mainly for complete logging, but has a benefit for engine safety. * Oil temperature input - mainly for complete logging, but has a benefit for engine safety. === Control Inputs === * Config switch. Currently on EC18 pin #16. * launch control enable. Currently on EC18 pin #12 * Shift cut cluch switch. Currently on EC18 pin #6 * RS232. I am led to belive I can have two of these now. #1 is now tracked to EC18 pin #14 and #15. Q: Does RS232 #2 go only to the pads near the MAX232 chip? === Summary of Inputs === Again, it seems I've used every pin at least once, and will need to introduce some more connectors too. The trick will be to work out what I don't need and what can be done more efficiently. I can then write down a good specification for my spare main board.
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