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Nitrous and AFR

S

Salvin

New CEG'er
Joined
Jun 15, 2005
Messages
8
Hello folks , wasnt sure where to post this so any moderator can move it if i've made it in the wrong section.

I'm currently running a Wizard of Nos nitrous system (UK brand) and I also have a FJO racing controll unit named Maximxer , the controll unit is awesome and i love the extra safety it provides but i've ran into a problem I've set the lowest AFR to 0.6 volt before the unit cuts the nitrous and fuel and this hasnt been a problem earlier cause i've only fired the nitrous on 5'th gear and on 3500+ rpm.

After a couple of runs i decided to see how it would run on 3'rd anf 4'th gear but then unit just keept shutting down as soon as I hit full throttle.

I decided to buy a narrowband AFR guage from autometer so see what was happening while driving and injecting the nitrous , and it looks like a chrismas tree while accelerating going from lean to rich a couple of times each second

It's only stable when the ecu hits the closed loop setting.

So my question is is there anyway to alter or change the singal comming from the lamda to maybe give me an avarage value or do i need something else? cause right now I cant use the nitrous untill the system hits the closed loop. :(

Any advice or input would be much appriciated.

/peter
 
Buy a window switch (rpm) to set up a range in which the nitrous will work. Either that or a simple rpm switch to set just the upper limit.
Heck for couple bucks you could build your own controller.

The O2 voltage switch is a nice safe guard but really a last ditch attempt to save the engine and not something I would use to control the limits of the nitrous.
A blinky light (A/F gauge) that uses the stock O2's is just that. A dancing light show. The stock O2 is only fairly accurate at stoich. (~.45 volts)
However it should peg on the rich side when accelerating. If it doesn't then you have issues! It should only oscillate under light load.
 
take off the janky setup and get a rpm window switch, and run it with just that and WOT. do yourself a favor and buy a WIDEBAND o2 so you dont blow your car up.....that guage is cheaper in the long run trust me.
 
Hello , thanks for the answers.

I'm running a 75 shot but i use the controller to pulse the pulsoids to smooth it out (starts at 15% then ramps it up during 2 seconds)

Hopefully i'm never gonna lean out (if no nitrous components fails) cause I have a custom map for every 200rpm that activates at 100% throttle and if the armswitch is activated, nothing is failsafe but it's as close as I can get.

The rpm thing is a good idea tho , the controller have that feature aswell.

My main reason for using the AFR value was as a last defence if a pulsoid blowsup on me.

You mention a wideband TRicker, will a wideband setup flicker less then a narrowband?
 
wideband is a must. one thing you should think about when you are working with a progressive controller is that they pulse the nitrous solenoid, your supposed to back it up with another solenoid that goes full open like a regular setup so that if the pulsing ruins the solenoid, there is one to shut the nitrous off....because when a solenoid goes bad, it stays wide open. which probably means your engine goes boom
 
I'm not using regular solenoids i'm using a fairly new type called pulsoids (made specificly for pulsing) and they should close if something fails.

Regarding wideband , I guess I have to remove the narrowband unit and replace it with a wideband , will this effect the ECU in anyway , or is it a straight switching the units and turn the key and it works?
 
Last edited:
actually it is a totally seperate probe. you can keep the stock 02's in and install the wideband by drilling a hole in the exhaust and welding in the supplied bung. it's actually easy, an exhaust shop could do it in 20 minutes tops. i did it by myself, took about a half hour because i removed the Y pipe to do it. the only downfall to a wideband is the cost!!
 
Sounds great , i'm picking up a wideband unit then.

Thanks alot TRicket and crew for the great input.

Much appriciated
 
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