Megasquirt Newbie Questions - All the really dumb ones you were afraid to ask!

cheers mate.i'll come back for sure with more questions

 

x2 for ditching the old wires where possible.

The metal crystals in copper become larger with age, and when subjected to repeated heat cycles. Because of this it loses conductivity, becomes more brittle and more likely to crack, hence I suppose why houses need rewires after 15-20 years or so. They might be fine, but on a 20 year-old car I'm using all new wires. They don't cost that much and it may save having to troubleshoot later on.

I read one of VWSingh's posts about using the stock fuseboard, with a digifant ecu relay and fuel pump relay, and just a couple of connections to change. I was going to go down the relay board/access board route but decided to keep it on the OE fuseboard because of this.

 

Once you get the Megasquirt running that is, and don't have the issues i've had for the last 12months.

i'm sure its good once its working right but mine hasn't work right from day one.

 

Fair Point ^^ especially when the wiring is in hot areas round the engine.

My logic for keeping as much of the OE stuff as possible, is that the OE connections are very solid and waterproof. On the whole, VAG wiring is pretty reliable when it's not mucked about with, even when it's 20 years old.

 

Copper "work hardens', which means the more you move it (including vibrations) the less subtle (more britle) it gets. It does not loose electrical conductivity though.

 

Fair enough Mark. It's been years since I studied materials science, it's a vague memory now! Would the copper inside the wires oxidise over such a period of time?

 

Thanks for your inputs guys.I'll start tomorrow removing the old loom and hope,with your help of course, to connect everything on the new loom right

cheers

 

So I've wired in the ignition as per the discussion. I just need to finish off the fuel pump relay wiring, bolt the inlet manifold and intake pipework together, and then I think it's time to plug it all in and see if it works.

 

great come back with your results

 

Hopefully the results won't be a small electrical fire, or major fuel leak

 

Hopefully NOT

 

As for the injectors wiring..i have 2 wires from the loom and 4 injectors which require 2 wires each.How am i supposed to connect them? ;p

 

A fused Power feed goes to the four injectors. What loom do you have? You should be following a diagram.

 

The loom if bought from RSA would have 2 inj1 and 2 inj2 flyleads. Others may just be 2 flyleads labelled inj1 and inj2. Inj1 can supply ECU earth for more than 2 injectors so you would be fine to connect cylinders 1 and 3 to this channel and 2 and 4 on the other.
Supply 12V from fuel pump output.

Note for previous installations I may have run 1 and 4 on one channel and 2 and 4 on the other. This will still work in batch mode. My revised grouping should improve running in "alternating" settings for 4 cylinders.

 

I have the MS loom from DIYautotune..Yes i am but because i didn't do such work in the past i want to be sure of what i'm doing

 

It has 2 labelled inj1 and inj2.So if i understood well i should have my inj1 connected to two wires and going each of them on 1 and 3 injectors and connect 2 wires also on the red wire labelled 12V and going on the other pin of the 1st and 3rd injectors?

Thanks both for your help

 

Not sure how your standard wiring is. But I fed my injectors from the fusebox using the feeds that originally supply the injectors. This isn't the case if you had kjet.

Solder inj1 pair of wires together on the loom, then join this to one wire coming from each of injectors 1&3. Do the same for 2&4 on inj2. The other wires from all 4 injectors can be soldered together and then connected to a fused 12v supply that is powered by either fuel pump relay or ecu relay.

 

The injector supply 12V will be common to all the injectors. The injectors are grounded by the ECU via inj1 or inj2 channels.

 

yep i was running k-jet before

cheers for your help guys i'll keep you posted

 

This 'N' connection, used to power the injectors, looks like it needs a seperate fuse. What size fuse should be used for four high-impedance injectors?

also, when it comes to sheilding the signal wires against noise, would a wrap of aluminium tape (grounded) do the job?