Nitrous issues...

[Waffles]

The nitrous was already installed when I bought my 96 Cobra, and I'm having multiple issues with it. I figured I could just address them one at a time. It's a Nitrous Express kit, with the upgrade kit that includes the pressure gauge, bottle warmer, purge, etc. It's also got a BMN window switch.

So here's my first issue... the nitrous is set to fire at 3200rpm at full throttle. When it hits, it doesn't hit all at once. It surges forward distinctly 3 times. You can feel it pull hard, then back off, then pull harder and back off again, then it unleashes hell. Anyone have ideas about why it could be surging like this? I haven't run nitrous before so I guess it could be normal, but for some reason I don't think so.

[Jeff88coupe]

What was the bottle pressure when you tested it? Did you purge the feed line before you hit it?

[Waffles]

Bottle pressure was right about 900psi and I did purge the line repeatedly.

[Jeff88coupe]

Check all the nitrous wiring..make sure all the connections are good. Also check the window switch connections including all grounds. The nitrous system only should work one way...all on or off.

[dedpedal]

3200 sounds kind of low in the rmp range to be engaging nitrous.

[92BlackStang]

id go 3500 if its a wet kit. sounds like you have a bad ground

[Waffles]

Okay, so I don't know much about this so bear with me. The second issue I didn't bring up before is that now, suddenly, the nitrous won't fire at all. With a multitester and a friend I went through the wiring of the system. It seems that the window switch, being hooked to the tach, just generates more voltage as RPMs increase. It does this until it generates enough to trip the relay that fires the solenoids. However the relay never trips. We replaced the relay and got no changes.

I'm not sure if maybe now the window switch is not generating enough voltage to trip the relay? If the window switch was starting to fail maybe that is what was causing the surging. Like, on off, on off, on....

Anyone else use the BMN Racing window switch?

[Timido]

I use a MSD window switch and have not had any problems with it. It controls the Ground side of my Nitrous Relay. Mine is set between 3000 and 7000rpm and the Msd is max chipped at 7200rpm. I run mine with a Wide open throttle switch, A fuel pressure hobbs switch and a Normally closed Transbrake solinoid.

You could always bypass the window switch and then try it as long as you are over 3000rpm and at wide open throttle you will be fine

[Waffles]

True enough. I had narrowed the problem with it not working entirely to the window switch/relay issue. Siolinoids are both working ok (it's a wet system). But I really could bypass the switch and just use a button to test the problem with it surging power. Not a bad idea. Thanks.

[Waffles]

Well I didn't test, but I called Cincy Speed and the very helpful fella I talked to agreed with my hypothesis. So I guess the plan is to try to get BMN to replace the switch (not going to happen since these guys haven't responded to a months worth of emails begging for trouble shooting help. When that doesn't happen, I'm picking up a digital MSD switch from Cincy Speed. Hopefully, it'll all be worked out then. :)

[Waffles]

Okay... update and new questions. I re-wired most of the nitrous system. I didn't like how it was setup before because I couldn't warm the bottle without arming the entire system. I also did away with the analog BMN switch. To their credit, BNMN is going to replace a switch which is 3 years old, no longer under warranty, and of which I am not the original purchaser. When I get the new switch (it's supposed to be new and improved) I'll list it here or eBay.

I picked up an MSD 8969 window switch from Cincy Speed for a bit over $100 and installed it, for the most part, last night. Here is what I don't know, since the old system was installed by the previous owner.

The other system used a relay to trigger the solinoid. The analog switch would increase voltage in relation to the RPMs until a threshhold was reached, the the relay would fire the solinoids. The previous owner told me the relay was part of the system from NX and needed to stay in place even with the new digital switch. The wiring schematics that came with the MSD shows no relay. Anyone know the answer?

Also, I am using the tach feed from the ECU. This is on a 96 Cobra, anyone know what mode the switch should be run on?

[Waffles]

I use a MSD window switch and have not had any problems with it. It controls the Ground side of my Nitrous Relay.

It seems this likely answers the first part of my question. I should have re-read the thread replies. :bigthumb

[Timido]

So does it work now with the Window?

[Waffles]

Well, I had to change a thing or two, but I'm 99% sure it's all together now. I had hooked the relay up wrong, and have it fixed now. Couldn't test it as I barely even made it home in the snow. First dry day I get we'll know something :)

[cstreu1026]

Does the car have IMRC's on it still? I would imagine that its important to make sure those are functioning properly as well.

[Waffles]

Yep I do, and yes it is, and yes they are. :)

So I couldn't really do much testing because of the weather and road condititions... BUT IT WORKS! A run up through 3rd busted the tires loose when it hit. I'm impressed. Much different without the switch chatter I was getting before.