NITROUS OXIDE ( nos / n2o ) advice forum

Ok, so really going to need some help with this concrninging wiring to tap in to for an RPM signal to my Max extreme, as I understand it I can patch into the cyl 1 injector wiring which is very convenient, so how do i determin which one, from the photos there are 3 wires to each injector, brown which is the common ground, and then red/white for all injectors and then there are six other individual colours for each injector for the 3rd wire, the close up below shows cyl 1



Thanks

You can use the common ground and set the number of cylinders within the maxy settings. This should give you the engine speed.

But isnt the ground just an earth to the chassis, how does that work?

It works as each triggered coil allows a momentary circuit connection. The Maxy will interpret this with the known number of cylinders. X number of pulses per Y number of cylinders = Z RPM.

Well if thats the case its a doddle to connect to

I hope that means 'easy'

Yes, what does it mean stateside??

Not the slightest LOL. I just know it's a british word.

https://en.oxforddictionaries.com/definition/doddle

Thanks, Dave, I looked it up shortly after my previous reply LOL. My Brit English (Bringlish?) is getting stronger now...

a couple of years ago i worked for an American company called Fastenal... I believe they are quite well known in America, and my branch manager was from Florida... The arguments we had over the English language was funny... I often had to remind him that the English invented the language long before America was discovered

I believe that story; I hear dumb shit similar to that from time to time.

And so that wire would connect to terminal R12 "RPM Input" of my max extreme...correct?

yup. From there it's all about setting up the number of cyls in the settings.

When I did it on my m54 engine I picked it up from one of the coils but couldn't get a steady reading when the throttle wasn't pressed it was flicking all over the place on the max screen but as soon as you touched the throttle it would be spot on

I put a switch on the Pedle to interrupt it till the pedle was pressed

You may not need to do this as I had an old controller

Interesting. It could have been some sort of interference it was picking up. Which controller was it that did this (just out of curiosity)?

It was the early max extreme unit that did it once I figured out it was doing it and put the switch inline it worked perfectly

It does say on one of the diagrams that a wire from the tacho is preferred but i have no idea how to find that feed

It's preferred but not required. It will still work.

Ok I connected the RPM input to the ground of the coil pack and set the No of cylinders to 6, but my home screen RPM just reads zero with the engine running, I did read about setting the RPM to 0 if the RPM link was not used so I set the lower one to 1000 and the upper to 6000rpm at the moment but still no rpm displayed?

Just had an intresting time this afternoon, the ground connection didnt work what ever cyl setting i used, so I traced the coil trigger wire and made a temp connection to it from the maxxy rpm input, set to 6 cyl started the engine and I had a bout 400rpm showing on the max, hmm I thought getting closer, tickover should be around 750 so logical thinking says try it on 12 cyl setting! heres the thing though and it all happened a bit quick cos I started panicking, the revs on the max were showing a really high rpm I think it was around 5000rpm and I heard some buzzing which moments later I learnt was the pulsoid/s as I then started to smell fuel!!! I have not got the pusoid outputs connected yet but there is fuel to one whch was then going into my engine bay. Turned everything off quickly and had a look, not much fuel spilt , i guess the jet kept it small.
Once everything settled down I set the rpm in the max right up to 6000 on both settings and then set the cyl to 3 which was a little closer to the tacho reading, long story short set it to 1 cyl and it was spot on....success
the 64million dollar question though is why did the pulsoid fire when I have no tps or microswitch fitted yet?

Also I tried soldering the RPM input to the coil trigger wire but it wouldnt take the solder, seems like a stainless type of wire, how would you join it.. crimps?

I must say this is all very challenging!

I know alot of people dont like them but would a scotchlok do the job I dont really want to cut the feed wire to put in an inline crimp?

That won't work because the vibration will cause it to lose connectivity and could cause poor performance of the nitrous system. I'd use an environmental butt splice so that it can be sealed with heat.