Project GigaSquirt

Recently I've been doing a lot of reading up on various engine management systems trying to find something suitable for my rather tricky application. My application being a supercharged VR6 which has an after market LPG system fitted. Lots of systems come close but I just don't feel any will fully satisfy my needs.
Having looked in detail at megasquirt I was quite surprised how simple it really is, therefore I have decided to start project Gigasquirt.

My aim is to put this project together with (hopefully) suggestions/help from you guys for features and a things I have overlooked. I will make all hardware and software available to the public domain but will take responsibility for adding any proven modification on the hardware or software to the project. I have designed it around a Microchip Digital Signal Controller for the time being however I will make this inter changeable so that other DSP's / Microcontrollers can be used so anyone else can have crack at the software or even use the megasquirt V2. My current specification is as follows:

Already designed.

12 x Injector drives all individually switch able (to allow sequential injection on petrol and LPG or even to run both at once) and current regulated by means of current chopper circuit.
2 x PWM outputs (N-Channel MOSFETS), one for ISV and one for boost control (I have an idea for that).
1 x Stepper motor drive, drive by wire?????
2 x K-type thermocouple inputs, one for EGT other spare.
1 x Manifold air temperature input.
1 x Manifold air pressure input.
1 x Coolant temperature input.
1 x Throttle position sensor input.

Still to design
1 x Crank position sensor (VR type).
1 x Cam TDC sensor input.
2 x knock sensor inut.
1 x Fuel pressure sensor input.
1 x Air fuel ratio. (I think I'm just use my Innovate LC-1 output for time being)

If anyone can see anything glaringly obvious that I have missed or would be useful please let me know in this thread.

Also, can anyone answer the following questions:
The drive current for a Bosch 2.4ohm injector?
Anyone who has fitted megasquirt to a VR6, did you leave the original ECU fitted for other ancillaries? e.g. fuel pump.
What's a good dwell time for the standard VR6 coil pack?
More to come, but I'll leave it at that for the time being.

Jonathan

SensibleDave on here fitted MS to his VR for a short while, so he should be able to help you on that front.

Drive by wire throttles are normally driven using an H bridge (from my experience anyway). Calibrating again isn't easy, and getting a good strategy for them isn't easy, as their are a few things to consider. Stiction of the throttle being one. PI or PID control required with finer control around zero point. You can integrate the idle control into the electronic throttle, but for the sake of ease I'd stick with the PWM output to an ISV for now.

Knock sensing is one of the most tricky things to get right. I have some strategies written in Matlab/simulink that you may find useful for that, but it is notoriously difficult to calibrate, and really needs a dyno and a lot of trial and error. We did a projetc for VW South Africa for the Citi Golf, and it took about 6 months for their calibration engineers to get it calibrated correctly

Might be worth considering barometric correction, although, unless you live/drive up and down mountains, it shouldn't make a huge difference.

Also might be worth considering EGT.

I've come across barometric correction before and just can't get my head around it. Surely if you have an absolute pressure which you get from MAP sensor, and the temperature you would know the mass of air going into the engine therefore be able to mix the correct amount of fuel with it. So what would you gain from knowing barometric pressure????

Am I just missing something here?

I will be able to monitor the EGT and was just going to use it for a warning, Does anyone recon it would be worth incorporating any engine protection if excessive temperatures were seen?

VR6Joni wrote:I've come across barometric correction before and just can't get my head around it. Surely if you have an absolute pressure which you get from MAP sensor, and the temperature you would know the mass of air going into the engine therefore be able to mix the correct amount of fuel with it. So what would you gain from knowing barometric pressure????

Am I just missing something here?

I will be able to monitor the EGT and was just going to use it for a warning, Does anyone recon it would be worth incorporating any engine protection if excessive temperatures were seen?

don't know.
i think in the begiining you should just log them and collect data,i.e try and get a handle on what sort of conditions and parameters values you get your high temperatures.
then maybe decide on a stratergy from there.

It does make a difference but im not going to read my whole Haltech manual as its a mine field in there, but the Haltech automatically during ignition on fuel pump prime takes this reading i think.

junkie wrote:It does make a difference but im not going to read my whole Haltech manual as its a mine field in there, but the Haltech automatically during ignition on fuel pump prime takes this reading i think.

I'd be interested to know what because I can't find a thing about it on the internet, only that some systems have the feature.