Inertia switch wiring

Hi All,
I'm about mid way through an LPG conversion on my 99, 4.6, and thought that I'd like to put an inertia switch on the feed to the ECU. Hopefully if we're unfortunate to get in a shunt, the petrol one will isolate the petrol and the gas one will shut off the gas. I've had a look at literally buying the same unit fitted to the car now, but am unsure of the wiring (Rave circuit diagrams!). If anyones had a go at this I'd appreciate their input.
Thanks

Depending on the system you're fitting, the gas injectors will be fed from the petrol ones.

If the inertia switch shuts them off, it'll also shut the gas ones off.

My system also takes a feed from the positive side of the injectors circuit to tell the LPG system when the ignition is switched on. Same deal, if the interita switch switches off the ignition circuit and petrol injectors, the LPG system shuts the valves, and the injectors off. In essence, it thinks you've turned the ignition off and so shuts down.

If you've got a new system, I'd be very surprised if your LPG kit doesn't have the same capability.

Thanks for the info - I'll get back to the suppliers and check that the system does the same as yours.

Mr Gorsky, while we're talking conversions - the installation wants a connection to the lambda signal wire ( one connection for each side) do you happen to know which out of the 4 present (orange connector) is the signal lead?
Thanks

MrGorsky said:

Depending on the system you're fitting, the gas injectors will be fed from the petrol ones.

.....

Click to expand...

Really....didn't know that....

So what are these on the top of my Intake Manifold if not Gas Injectors??

I though all LPG installations had their own gas injectors - mine certainly has?

Simmer down, simmer down.

I meant the gas injectors are electronically fed from the petrol injectors. We were talking about an electrical switch after all. That is to say, the LPG system fires it's gas injectors by monitoring the firing of the petrol injectors. Most systems also take the positive electrical feed to the petrol injectors so they can monitor when the ignition is switched on. Therefore, when the petrol injector circuit is switched off in the event of a shunt, the LPG system is shut off too.

Is yours a THOR Forthbridge? Mine's a GEMS, but I'll have a look at the wiring and get back to you.

I cut in to my Lambda wires right next to the ECU so the connections were in the box and there was a bit of room to swing my soldering iron.

So for the GEMS engine....

Here are the connectors to the engine ECU.



We are interested in the 36 pin RED Connector (C507)

Pin 34 is BANK A (Orange wire)



Pin 8 is BANK B (Green Wire)



As I said, I cut in to my wires right there next to the ECU rather than follow them all the way under the car. There was more room. Although I don't think you actually cut the wires, you just need to attach the LPG wire to it.

The THOR will be different. Leave it with me....

And for THOR....



We need Connector 2 (C0635).

PIN 15 is the LEFT HAND BANK



PIN 16 is the RIGHT HAND BANK



I don't have THOR so I don't know what they look like, but there are the pins.

Mr Gorsky,
thanks for all the work you've put in. My cars got a Thor engine so I'll be taking a feed off of the 15 & 16 pins. Getting to them from the ECU is helpfull as I've got to take the RPM feed off the grey wire in that part of the loom. Is RH bank as you look at the car from the front or as you sit in the drivers seat (just so it all matches with the extra loom which is bank 1 and 2, which relates to injectors a-d and e-h!)? Thanks again

Nice bit of work there McGorsky.

forthbridge said:

Getting to them from the ECU is helpfull as I've got to take the RPM feed off the grey wire in that part of the loom. Is RH bank as you look at the car from the front or as you sit in the drivers seat (just so it all matches with the extra loom which is bank 1 and 2, which relates to injectors a-d and e-h!)? Thanks again

Click to expand...

It's taken as you sit in the drivers seat. The right hand rocker cover is the one with the oil filler in it.

(Engine speed output Connector C0637 Pin 17)

dogsbody said:

Nice bit of work there MrGorsky.

Click to expand...

Thank you!

MrGorsky,
I have to agree with Dogsbody - nice work, you made a nice easy job of it all for me. I split the ECU yesterday and all was much clearer, managed to remove the pins from the block and connect the new wires and some heat shrink. A much neater job than I was anticipating. While I was there I got hold of the grey RPM feed too. My system allows for connection to the OBD connector ( Pin 7) so thats next. Thanks again.

I wish I'd done that with mine! Next time I will.

Does it just take the rpm signal from the ODB connector or other signals too?

I only ask because I have heard people complain that when their system uses the ODB connector, you can't connect a fault reader at the same time.

Not a huge problem I suspect, but I think there is an advantage to be able to read the long and short term fuel trims (on a Nanocom for example) when fine tuning your LPG system, so having a free ODB socket might be advantageous.

Got to say - I don't know!, The suppliers suggested it as, I think, it'll help it self calibrate? On my system ( Bigas) it involved using one of the redundant Grey Lambda wires into another point on the gas ECU, and then running this to the OBD plug (which from the paperwork on Rave looks like C0040).

Mine is a BiGas system too. It's a few years old now though, and I didn't have a connection to the OBD socket.

Either way, following the instructions is probably the best way forward! When you do the self calibrate, it certainly needs to know the engine speed.

To be honest, the self calibrate is pretty good, and it'll get it within a gnats of perfect. It's when the engine goes open loop on full open throttle, and when it's at tickover that you might need to tweak it. You'll have some fun doing that...

Yes I've been looking forward to plugging it in - still a way off that yet. Tank end now. Looks like fun trying to manage to get the gas supply a minimum of 100mm from any exhaust pipe. Main thing is the car runs with all the bits and pieces on it, so at least the petrol side is still working fine. I didn't fancy finding an inlet manifold leak, there's too much stuff bolted to it now just to pop it off! How's your Bigas system performing, we've a zavoli on the other car which I must say hasn't missed a beat in 2 1/2 years. Did you get the twin vapouriser with yours?

Mine was fitted to my Jag before I got my RR. I took it out of the jag before I sold it.

It's been faultless in both cars for 4 years now.

If you can't get the pipe 100mm away from the exhaust, you have to make a heat shield out of aluminium or something.

You need to put washers on your tank mounting bolts too. Minimum size is 50mm by 3mm thick. eBay do them in stainless (not cheap though). That caught me out at my inspection.

Thanks for the info - I was beginning to think that the exhaust was going to be a pain. Goes the tank have to be level? I've checked the boot floor and its out - not by a lot but not level. Not that the LED guages are accurate....