Skoda Rally Blog

Well, since the last entry, I’ve done a fair bit of work on the car. Firstly, getting it MOTd, but that’s by the by. The important work has been getting the MegaSquirt ECU up and running. Doing any project like this it’s always easy to under-estimate the amount of time it takes to do little things to get it all running, and I think I’ve done that in this case. Anyway, first up was getting a fuel return plumbed it – the system that I’m using requires a constant flow, meaning that a new return had to be plumbed back to the tank. As it’s a rally car, this needs to go inside the car (not under the floor) to stop it being ripped off on a forest stage. And that means that it needs to either be braided hose (with no joints inside the cabin) or solid metal. As the other pipes were like that, that’s what I’ve done. A high-pressure pump is waiting to replace the current one – thanks to German, Swedish and French it only cost ?55 for a new pump, rather than the ?200+ I had been quoted by some people…..

The wiring of the MS is made easier by having a relay/connection box under the bonnet, and then an umbilical connection to the MS ECU, which is better off inside the cabin of the car. This is now done, although soldering 18 connections to the ECU end while inside the car (this has to be done as the plug is too big to cut a hole for in the bulkhead to be safe for fireproofing) took a while. And again, getting the power and ground wires connected took more time than I thought they would. But getting it in the car (at the bottom of the dash), and having it power up was a great moment. And then connecting the sensors that I could do – a signal from the coil so the ECU knows how fast the engine is running, the coolant temperature sensor, and the tube for the Manifold Absolute Pressure (MAP) sensor meant that I could run the car and see the MS react as it would do if it were running the car! At last, it all seems to be making sense.

Next up was making the wiring loom, which I wanted to make as professionally as possible, so I made sure it had all the right colour coding on it, and was taped up, etc. It looks pretty good – not home-made, for sure.

And then, fitting the oxygen sensor to the exhaust. I had planned to use a new downpipe, but this turned out to be short (because of having a catalytic converter on it), so instead I’ve got a suitable bit of threaded pipe, and welded that into the downpipe. The wiring for all this uses the standard Skoda/Bosch connectors, so that looks good.

And once again, running the MS with that on and seeing just how off my mixture currently is (with the carb on it) was a good feeling – it finally feels as if it’s going to work. I’ve painted the manifold today (quite a few coats of satin black Hammerite), and hopefully should get it bolted up tomorrow. I’ve made up the bracket for the throttle cable (although I’ll have to make a stop for the pedal as it’s short travel at the moment, and making it longer travel would be too much work at the moment), and I think that it’s all ready to go – obviously there may be a few minor ‘gotchas’, but it should all be running (at least ticking over) by Sunday morning. Which admittedly only leaves me three days to get the mapping right, but given how wrong the carburettor is, I’m hoping that even that will be better than what I have!