The V8 Owners Forum -

The MS external wiring diagram shows fuses feeding injectors etc. On the rare occasion you'd need to have MS powered up but not them, you'd simply pull them?

You could wire the "fuel pump" relay to deliver power to a fuse box and then drive the pump, injectors and COP off fuses in that box. Then you can just pull the fuses you want to disable spark or whatever. You can always just pull the pump fuse when you switch tunerstudio into test mode to test items such as spark and injector pulsing, etc. You can use the "pump on/off" option in test mode to switch the entire fuse box on or off...

That's how I did it on the Cobra

I'm currently no further on with the car really. Everything else is done. I started, and acutally mostly completed a wiring loom, but nothing works

Is this the injection loom only? Did you draw the circuit first?

Like nothing at all ?

The engine is all wired up with the ms3pro, starter and alternator. Innovate LC1 wideband with gauge and rev counter wired correctly from what i can tell. Three mechanical gauges (boost, oil temp/pressure and water)

I used two breakers from the battery (300a and 150a)

I bought a 5 relay/10 fuse board all prewired. Wired it all up as per advice from several sources, did one circuit at a time as advised. Have one main relay which switches the others.

Fuel pumps are on their own separate feed with twin relays triggered by ecu

Hooked up the main battery feed and the wired got warm. So I have a short or something but I can't find it and don't really know what I am looking for. I've thrown the towel in, 5yrs+ and £25k on the build ffs and I can't afford to pay someone to rewire it and no one wants to touch it as it is.

Not much help now, but it pays to draw it all out first. Then wire to that. Much easier to spot a mistake in a diagram. Or to check your loom against it in event of one.

Does the entire engine loom come off the car? If so I'd be happy to check it out in my workshop. Much easier than trying to do it on the car.

getting warm is bad.

In the meantime, you could add a small circuit breaker and use that as a primary connection to the battery so at least you lessen teh risk of fire/damage whilst troubleshooting the problem

But getting warm straight away ( presumably big sparks when connecting the battery ? ) is a sign of a pretty bad short circuit.

Either trace wires, or remove all fuses and relays to isolate stuff and start trying to pinpoint where the problem lies. Unplug ecu and any other electronics too.

I can imagine nobody wanting to take it on....trying to work through someone elses wiring would be a nightmare, and very very time consuming. Which will add up to lots of money.

Or just stick all the OEM wiring back in lol.

Where abouts are you? If you're local to me I'd have a look if you kept me supplied with tea.

I drew individual diagrams of each of the circuits yes. Still have them, although never been checked by anyone else. I have gone through them but will do so again at some point, when I can.

It got warm gradually over a minute or two, not bad sparks.. I didn't have the grounding resistor connected through the FIA kill switch, but I didn't think that would be it as that's primarily to ground the alternator out in case of flicking the kill switch. Before i do anything else this is getting connected in.

Fuses weren't in an ECU wasn't connected, just in case something like this happened.

Main wiring goes Battery > Kill Switch > 300amp breaker, which splits off to starter/alternator and then > 150amp breaker prior to the two feeds for the fuse board and fuel pump subloom. Scuddefish thanks for the kind offer but it's not that easy to remove, half due to the wire routing and also due to other connections to other bits of the loom eg LC1 etc. I used the MS3 guide for wiring the engine and LC1 etc. and it all went pretty well I think.

The problem is the main loom/starter circuit I think. The wire that got hot was the first one from battery to breaker. It makes me think the breaker might be the issue?

Makes me think that wire is under sized.
But I am no expert on wire sizing

Ian

With no load on anything....nothing should be getting hot at almost any wire size.

get a small circuit breaker into the main feed for now, so you can safely turn things on, and try and find the short. No sense using a fuse as you might go through a load of them trying to troubleshoot.

Maybe something 3-5A to start with. That should put no cables at any real risk anywhere, and allow you to power up things like the ecu.

Then once you're happy the main feed at least seems ok, you could remove it.

I hear what you say Stevie, but the circuit breaker is there to protect the wiring and items attached. Main breaker 300 amp so wire from battery to breaker if it got hot can run less than 300 amp. So it is undersized. If the 300 amp breaker did not break the short is on the hot side( battery to) of the breaker

However I see your logic in your test method. Better at 5 amp than 300

Ian

The only thing likely to pull anywhere near 300A is the starter...and he said nothing works.

Simply powering the ecu would barely be 1A etc.

There is nothing on a car that simply turning the ignition on should cause any wiring to get hot, or even remotely warm, not even a very small wire. There must be a short circuit somewhere....but yes as you say, you could have a hell of a short circuit but still under 300A breaking capacity of the breaker.....but then if it were any big number...the wire wouldnt just be warm, it would be quickly identifying itself with lots of blistering, melting, smoke and maybe fire lol

The wire from the battery to the breaker via the FIA kill switch is absolutely massive, like Gauge 1 or something.

My money is on the kill switch being faulty, but as I said I need to find time to actually test it.

In the meantime I can post pics of my sublooms if anyone is interested / can check them out for me??