Testing the Fan Control
I'd very much like to get rid of the silly otter switch arrangement found in Griffiths.
There are 2 fans on the later Griffs. My current plan is to control them independantly from the fan and water pump controls from VEMS, with different on temperatures and different levels of hysteresis.
There's no real reason for this, other than it's giving me options...
Well, after an exhausting search for the coil wires on the fan relays (they went into the engine bay and came out again...) I plugged them in to VEMS, set the temperatures and they worked. First time too. It's a shame the temp sensor isn't configured right yet.
Note that temperature calibration is now correct.
- I noticed the relays have diodes built into them. Nice and easy!
- what type of relays ? Most relays don't have flyback diode inside
- They're a Lucas/Bosch 5 terminal relay used on the TVR and Range Rover. The diode is (obviously) across the coil terminals. The original ECU needed the diodes or it sulked in a fairly major way! Will look up the part number and post it here.
- what type of relays ? Most relays don't have flyback diode inside
Fuel pump
Fuel pump relay has been connected. I'm using EC36 pin15 - P259 channel 5. I'm using 3.5 seconds for initial prime and it continues for a second after the engine stops. Both parameters unscientifically measured from the previous ECU.
It's often a good idea to use free injector outputs (If you still have some free) first (more rigid) before using up p259 outputs. Measure resistance of relays (and inductivity too if your DVM supports L measurement).
I have 8 injectors running sequentially so there's none spare. I've used the same relay as the fans have (ie those with added diode) so I have at least the illusion of protection for P259.
Tacho Output
Should have been simple, but the tacho in the TVR originally took its output from the -ve terminal of the old coil. There's not quite enough drive from P259 to solve this, so I need to think a bit more... Probably going to make a tacho driver circuit as I don't have any IGBT channels to spare.
Evaporative Emissions Control
I ought to be a good boy and sort this out properly. I've ignored it up to now, and I really shouldn't...
The vent pipe from the fuel tank goes to a carbon canister in the inner wing (not examined yet, I disconnected the system at the tank end). Another pipe comes from this to the plenum on the engine. Presumably the carbon canister is also vented to atmosphere with a non-return valve, i.e. it can suck air in, but not let it and the petrol fumes out.
Under certain conditions - not sure what these are yet, but guessing at warm engine, low RPM & low MAP - a solenoid is pulsed to evacuate the carbon canister of any fuel vapour it's collected.
Question: How best do I drive the purge solenoid with VEMS. I thought about a Misc output channel, but there's no temperature dependance on it. Am I understanding this correctly?
Solenoid frequency is expected to be approx 10 Hz and have a duty cycle of approx 10%. I don't think that this needs to be varied with anything other than to be switched on during warm cruising and off at other times.
I could make an external board to be triggered with a misc output, but that would be admitting defeat! I suppose I could use the boost control output, but this seems a bit of a waste, and still doesn't solve the temperature issue.
A: Please write a detailed proposal for what parameters to configure and how it should work. Sounds like a simple task for someone of our skilled developers :)
The largest problem now is the config variable count, please keep them as few as possible. //Emil
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