NITROUS OXIDE ( nos / n2o ) advice forum

Dave knows the Maxy in scrutinous detail and that's why I recommended chatting with him.

I have just realised from Davids message that I have also not grounded the unused inputs marked with an asterisk on the connection diagram ( I blame the small print), so I will try the trigger load setting and the grounding of the unused inputs at the weekend weather permitting.

I have just done as David advised but disapointingly it did not cure my problem, rather irritating as the work involved and the fact that im missing out on a useful function of the maxxy, so it looks as if Im going to have to utilise a microswitch on the accelerator (gas) pedal, I know you have told me this is how you have yours set up, is there a wiring diagram? Not sure where to wire in the microswitch whilst still benefitting from the Maxxy's fuctions

Using a microswitch isn't a big loss, so don't feel too bad about it. simply take the microswitch and have one terminal connect to 12+V and the other terminal to the R10 trigger wire and that's it.

Yes I can see that on the wiring schematic now, can i take the 12v out of the arming switch so it will be protected by the same fuse? Presumably this method of switching is low current due to the size of the R10 terminal and cable which can be utilised in it?

You can do it that way. The trigger wire draws virtually nothing in current, it's only used to 'read' voltage to know when to activate the nitrous.

Ive ordered a microswitch, so all the other benefits of the Maxxy will work its just the TPS bit which isnt used?

The sun is shining, wife has gone out with the mother in law, what could be better.....? Well continuing with my installation of course Microswitch fitted and wired in, the BMW throttle box set up is made for a microswitch set up, theres even a radius'd ridge on the back of the pedal to activate the switch. Set the rpm to zero and activated the switch, pulsoids buzzin away a good'un. Set the RPM to 2000 min and nothing so that part of the max is working great. What min RPM setting would you recommend


Ive definately broken the back of it now (i hope), I'm going to order myself a pressure transducer before i get the bottle filled, i've already installed the cabling for it and will probably fit a bottle heater at some stage too.

I know I've still got some work to do but whilst I get to that I have been playing with the power settings to get a feel for it, what baseline settings would you recommend I start with, eg power, build time and delay time for the 1st gear and then for the other 5 gears. Am i correct that the delay time setting for the 1st gear is to slightly delay the delivery of the nitrous to prevent an overly lean mixture and what sort of figure should I start with, bearing in mind the engine in question? Thanks

Bottle heater relay wired in, Nitrous transducer ordered, once that arrives it will be a quck wire up and then just need to get bottle filled before I start testing.

Time to start grinning

Transducer arrived this week and im picking up the filled bottle on Monday, just looking at my transducer and its slightly different from the nos manuals, on the max wiring diagram it shows a +12v R1 feeding the transducer, but the packing mine came in says 5v DC, so does that mean I need to use either R4 or R5 +6v to feed to it?

It sounds like the 5v is the output of the sensor, instead of the input volts. It should be 12v power, ground (earth), and 0-5 v signal out.

Heres the label on the packet

Yea I'm not sure about that one. Ask the highpower guys to see what you can use with it. The 6v outputs are not constant outputs, they're conditional so I don't think it would be good to use them for that purpose.

I've spoken to David about the transducer voltage and he's not sure either, he's going to look into it and get back to me. I was hoping to fit it today to start testing, I have rigged up a temperarary heating pad to run off of mains power and so wanted to see what pressure Im getting.

Anyway that hasnt stopped me, I looked up a nitrous temp pressure graph which told me I should be looking at about 88F for 950psi, which is what I heated the bottle up to, all the time measuring with my infra red thermostat gun, to do a static test. Now I must admit I was/am nervous. The Pulsoids came with a 50 nitrous and a 20 fuel jet which I thought should be a good starting point as from what ive read on the forum from other BMW owners are running at around 3:1 because of the high fuel pressure, so got the motor revving to 2000 rpm and hit the run sim button on the max.

The revs rose very quickly and were going to go into the red line had I not aborted before then, although it was slowing at the end. Im just going to let the bottle cool down a bit and then try another static test at around 73F which should equate to 800psi on the Nos. Ive just tried that and the revs are still very high, I aborted at the red line 6500rpm. I will probably try again tomorrow with the bottle temp at ambient which is only 15C at the moment. If everything is as it shoud be it looks as if my AF ratio is too weak, maybe my fuel pressure is lower than I thought. As a newbie im not sure how much a difference the pressur/temp will make. Definately a chemical smell from the exhaust fumes whilst testing, I presume that is the Nos and is normal?

There's a high likelihood that your fuel pressure is much lower at low engine loads. I bet if you check your fuel pressure physically, it'll jump up between hi and low pressure under WOT and cruise. It's quite tough to do the static test these day with modern fuel systems that have independent fuel pump maps. A 50:25 would still be right on the money on a standard 40 psi. but richer on 60 psi, so either way you won't break anything.

If you have the means, you can verify the fuel pressures with a gauge or a scanner tool.

Its a 2003 car so not that modern, I might buy a gauge tester they are quite cheap and I'd rather be sure, according to another thread the fuel pressure for this car should be around 50psi but dont know if thats variable or not, but you reckon a 50 nitrous and 20 fuel should be OK, what about the different temps/pressures?

Both of my vehicles have variable fuel pressure maps, it's still possible that is what may be your situation: a 35 psi idle that increases to the 50 psi.

David just emailed to advise it would be fine to use one of the 6v outputs from the Max Extreme to power the transducer, I will do that tomorrow then I can be sure about the nitrous pressure, ive already set the pressure to 1000psi in the alarms menu.

Ive had a problem with the pressure transducer sealing properly and have come to the conclusion something is wrong with the parts I have been sent, please see the attached pictures, firstly I tried using the dowty seal supplied but it is very tight fit and won’t sit flat on the face of the transducer and secondly the transducer has too much thread on it for the supplied t piece and bottoms out before compressing the seal anyway. The T-piece has what loos like a tapered face inside for a olive to sit against, tried last night with some loctite 243 sealer but that didn’t work either

On the voltage matter below, I connected up the transducer as advised to the 6v output and it worked fine except with no pressure applied the max was reading 150PSI and I managed to reduce this to 20PSI with the calibration function on the max, this indicated to me that the transducer is reading too high because it is indeed designed to work with a 5v supply and not the 6v which is giving the high reading.

I have emailed David for some support