The system is a Nitrous Express wet system. 100 hp shot. It has a WOT switch, a fuel pressure switch and an MSD window switch, 3000 - 6000 rpm.

Open the bottle, flip the switch and punch it. When it hits 3000 rpm you can feel a slight surge as the window switch allows the Nitrous to flow. That is about all I get in first and 2nd gear. In 3rd gear, it is fine. At 3000 rpm you get that initial surge and then a half second later the car goes "mental" right up to 6000 rpm.

The window switch was only recently installed, could the window switch be causing the problem??

Before the window switch was installed, the nitrous was available in 2nd gear. The car would hesitate and then go "mental". Seems kinda funny to me, so I'm wondering if the window switch is somehow responsible for this curious condition.

And yes, the bottle was full ...

Thx for any help

LWM

 

Almost sounds to me like it's running out of fuel, what do you have for a pump?

 

You need to bypass the switches one at a time to narrow it down. If it worked before you installed the window switch and now it doesn't...well that's a likely suspect, but I'd still check each one individually. Do you have a fuel pressure gauge? If so, does it fluctuate? What pressure do you have it set to trip at? Could be set to close to the actual pressure and takes a dip when the system first comes on and it stabilizes after a short period.

 

thx, I shall look into the fuel supply issue.

The fuel system is all stock

LWM

 

Is it hitting the turn off point on the window switch before the nitrous gets to flowing well and the car goes "mental" as you put it?

I know that in my car, the initial hit on the 1-2 shift when spraying is hard enough to kick my foot back off the pedal just enough to stop the nitrous, but keep the car at WOT.

 

No, in 2nd gear all I get is that little surge that indicates the system did fire up, then it is just like regular 2nd gear, lots of time for the nitrous to work its magic, it just doesn't. Then in 3rd gear, I get that same little surge followed by a real and prolonged surge of power ... (car going mental).

thx

LWM

 

Ok, the fact that the system works at all in 3rd gear indicates that it's probably wired correctly.

I suppose it's *possible* to wire it so that it only works in certain gears, but I have no clue how you would do that.

I have just one other idea. Do you have a purge kit installed? Given that you're running a wet kit, I suppose it's possible that the liquid nitrous is exaporating in the lines and turning to a gas. If you don't purge, then when it sprays you'll get a pause before it actually hits. Why you'd be getting THAT long a pause, I don't know.

What about the converter or clutches in the transmission, could there be more slippage than you're realizing and the extra power being lost to slippage?

 

I thought about this a lot last night...I'd definitely bypass the FPSS and see if that helps.

 

I definitely would not, especially if this is caused by a fuel pump that isn't keeping up on the initial hit in first and second.

 

First of all do not bypass the FPSS!!! If in fact your fuel pump is not working right (hence it cutting out) if you bypass the FPSS and it goes lean, then goodbye motor. Of course if you bypass the FPSS it will work, but the switch is there for a reason, your fuel pressure is dropping so of course your kit is turning off. That's the whole point of the switch.

First try to purge it before making a full run, arm the system and go WOT through a couple of gears to get good nitrous up the the solenoids. Also, make sure the bottle pressure is in the right operating range. Bottle pressure and the amount of nitrous in the bottle can be huge factors. Although I can almost guarantee that it is your fuel pump. I had the same problem with mine, with a 100 shot it was always cutting out and never fully stayed on. I put in a 255lph and now with a 150 shot it works just fine through all the gears. Hope that helps.

 

I don't understand how the fuel pump can't keep up with the demand in 1st and 2nd, but it can in 3rd. That just doesn't make any sense to me. Granted, bypassing the FPSS isn't something you want to do for more than a test run or two, but it's a way to test.

Besides, he (assuming he) can jet the car lower and test it.

And try bypassing the window switch and see what you get.

 

Well it could be a lot of things- for instance when I first started using a 1 gallon fuel cell for my stand alone nitrous system, I didn't realize I wasnt putting enough gas in it. It wouldn't come on in first or second because the weight transfer was moving the fuel off the sump of my 1 gallon fuel cell, about 3rd it would kick in.

If I had bypassed my fuel pressure switch, I would have exposed my engine to a 100 horsepower jetting of nitrous with no fuel enrichment. Cast/hyp piston motor isn't going to like that for long.

If it were me, I would tape 2 lights to the dash- splice one before the fuel pressure safety switch to make sure you are getting power to the fpss and one after the fpss to see what is going on after the fpss.

This could be so many things, could be the fpss isn't grounded properly, etc, etc. Just play it safe .

 

Mine acted simular after install..just took a day of trouble shooting to find out what it was. It was a faulty arming switch in my case. The way I worked my way through it was take off the CAI so I could see in the elbow where my nozzle went. I then disconnected the bottle (valved it off). Then I disconnected all safety's except window swicth...had my buddy in the car revving it to 3500rpm and me looking in elbow with a flashlight. I could see the fuel spraying. I then would add one safety at a time activating the WOT switch by hand and finally narrowed it down to the problem. Once I figured it out I tried the system with all safety's on and the nitrous to make sure it wasn't a bad solenoid...once I saw and heard the spray working ( already knew fuel was because of trouble shooting steps ) I buttoned it uop and was ready to go. Worked like a charm since. This is just a method I used...I'm sure there are probably easier ways...you need to eliminate some of the variables are go from there.

 

I don't know either why the kit wouldnt work in the first few gear and then kick in on 3rd gear. (Fuel Pump) My kit was very tempermental, it would work in 1st then it wouldn't. Or else it would work in 1st and not in 3rd or vice versa. All I know is that after I replaced the pump everything is fine. LIKE BUTTER!!!!!

just my .02

 

Give it a break, I'm not suggesting he leave it that way or even spray that way...he's got a fuel pressure gauge (according to his signature), and if he had a fuel problem THAT obvious, it'd already be showing other signs. Bypass it, or lower the setting using a meter...whichever you prefer. If it's delivering enough fuel in 3rd, I doubt he's got a pump problem. Until you rule out the FPSS is set too close to the actual fuel pressure, there's not much point in speculating what else it can be.

No way it's just a purge issue...I rarely even purge my line and you can still feel the hit nearly instantaneously. It's primarily for show and to get that last little bit of advantage.

Pull it from the intake and bypass the triggers one at a time...no harm, no foul. Some of these things are pretty basic...I didn't realize I'd need to explain it step by step. If you're using nitrous, you should at least be familiar with how the system works and the diagnostic steps to correcting it.