MembersPage/DavidBlades/Regeneration (2020-01-09 22:29:55)

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.

I have found the wiki pages for the EC-10 connector. This is incorporated into my plan, but I will use an EC-12 connector instead to make a bit more room!

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 - I am assuming the 4 outputs appear on the EC-10 connector.

Fuelling Outputs

Ignition Outputs

Idle control Outputs

Misc Outputs

Summary of Outputs

In theory I have some spare P259 outputs if I use the 4 extra NFETs. The use of NFETs should make the implementation considerably more robust.

Inputs

Sensor Inputs

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 the EC-10 connector. 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.

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? I have spare capacity on the EC-10 where I assume wheelspeed #2 will live.

Control Inputs

Summary of Inputs

It appears I can fit everything I want in to the ECU connectors assuming my EC-12 wiring is possible. The goal is now to reduce the number of "green wire" customisations to the minimum.

Proposed Pinout

EC36 PinSignal Name EC18 PinSignal Name EC12 PinSignal Name
EC36-1Throttle Position Sensor signal EC18-1WBO2 #2 Nernst Cell EC12-1Fuel pump - NFET1 (spareA?)
EC36-2Intake Air Temperature signal EC18-2Launch switch (analog ch5) EC12-2Purge solenoid - NFET2 (spareB?)
EC36-3Shift Lamp (P259 ch4) EC18-3Map switch input (analog ch2) EC12-3Fan #1 - NFET3 (S259 spare?)
EC36-4Tacho output (P259 ch0) EC18-4Stepper A EC12-4Fan #2 - NFET4 (S259 spare?)
EC36-5High-Power Ground (GND5) EC18-5Stepper C EC12-5Knock #1
EC36-6Injector 7 EC18-6Fuel Temperature (analog ch6) EC12-6Knock #2
EC36-7Injector 1 EC18-7WBO2 #1#2 Pump - EC12-7Wheelspeed #1
EC36-8Injector 3 EC18-8WBO2 #2 Pump + EC12-8Wheelspeed #2
EC36-9Injector 5 EC18-9WBO2 #1 Pump + EC12-9RS232 ch2 TX or Spare (analog in) [TBD]
EC36-10Coil #7 EC18-10Stepper B EC12-10Shift cut (analog in)
EC36-11Coil #4 EC18-11Stepper D EC12-11Spare (analog in)
EC36-12Coil #5 EC18-12Oil Temperature (analog ch7) EC12-12Sig GND
EC36-13Secondary Trigger (Hall) EC18-13WBO2 #1 Nernst Cell
EC36-14Coolant Temperature signal EC18-14RS232 (pin3)
EC36-15Not currently used (P259 ch5) EC18-15RS232 (pin2)
EC36-16Not currently used (P259 ch1) EC18-16Oil pressure (Analog ch1)
EC36-17Injector 8 EC18-17WBO2 #2 Heater -
EC36-18Injector 6 EC18-18WBO2 #1 Heater -
EC36-19Injector 2
EC36-20Injector 4
EC36-21High-Power Ground (GND5)
EC36-22High-Power Ground (GND5)
EC36-23Flyback - Keep 30V trans suppressor scheme
EC36-24Coil #6
EC36-25Vbatt - Additional conditioning?
EC36-26Ground (ECU and signal GND, eg. VR-, CLT, IAT)
EC36-27Primary Trigger
EC36-28To Hall sensor for cam position
EC36-29Throttle Position Sensor supply
EC36-30Not currently used (P259 ch7)
EC36-31Not currently used (P259 ch6)
EC36-32High-Power Ground (GND5)
EC36-33Coil #1
EC36-34Coil #2
EC36-35Coil #0
EC36-36Coil #3