Nox

04 A4 GTO Zex Direct Port

I am getting a lean spike at 3250 when my direct port activates. I am sure it is caused by the nitrous fuel lines draining the fuel rails. I dont think the stock pump can keep up with that first pull. It catches up very quickly, however, that lean spike makes me nervous.

Any ideas on what could help, until the fuel pumps for the GTO's come out?

kostya_f

It is caused by pressure differences in the lines (fuel and nitrous). Try using a FPSS after the fuel solenoid(s).

Nox

this would just cause a slight delay in the nitrous, correct? once the fuel catches up the n2o solenoid would then fire.

Nox

also, i am getting a stumble at the activation point. everytime i hit 3250 the car stumbles slightly. my logs show a drop of 100-150 rpm at activation. this drop in rpm coincides with the lean spike.

any idea why?

Nitro Dave's Nitrous Outlet

iTrader: (25)

You should put the universal walboro intank fuel pump in it.This will work.You could also look into installing a fuel accumalater from NX on this system.The stumble is from having no fuel.I would not run it like that.You will more than likely hurt something.
Dave

Nox

I am surprised that if the walbro will work, that nobody else has done it. I will look into that. Do you offer them for sale?

I have no plans to run it until the fuel issue is resolved.

GM Muscle

iTrader: (9)

If the GTOs has the FP regulator in the tank like the f-bodies and vettes, that's part of your problem too. The accumulator may help, I havn't tried one. I've been getting split second lean spikes as high as 16-18.0 for 3 years and it's never done any damage, it's pretty common when pulling a larger wet shot off the rails.

Nox

in addition to the lean spike, it causes the car to stumble until the fuel catches up. i think i will just go methanol injection.

Magic Chicken

iTrader: (1)

not sure if the methanol is going to solve your problem, but let us know

Nox

well, if i have a capable stand alone fuel supply for the n2o i am hoping that would eliminate the lean condition.

why do you think it might not help?

red90cobra

iTrader: (36)

i think they are saying when the noids open the n20 travels faster than the fuel. Makeing a lean condition for that split second. How do you expect the methanol to hit and atomize the same time as the n20. It would be the same as the fuel unless you somehow figure out how to let the fuel noid open first and then the n20. Then it wouldn't have a lean spike. I doubt it would have a rich either since the n20, but you might get puddling. Get a fuel pump man that'll fix the problem. You just might be cavatationg the rails for a split second and you just dont' get enough fuel in the line, and injectors.

necrocannibal

iTrader: (5)

Ive got a stand alone fuel sysem on mine and when I first hit it it spikes lean for about 500 rpms then drops off and evens out. I just assumed it was because the nitrous is running around 1000 psi and the fuel is only running around 10 psi causing the nitrous the reach the motor first. I havent worried about it as it only lasts for less then a second and its not ungodly lean but still is lean nontheless.

Green Thunder

iTrader: (11)

Hey Dave..
Any info on this accumulator?

Nitro Dave's Nitrous Outlet

iTrader: (25)

Yes the stand alone fuel system will solve your problem.
I have customers that have installed the intank walboro on the GTO.

The fuel accumalater was desighned for instances like this.When trying to feed all those lines and rails at the same time there is a fuel volume drop.The accumalater is a back up resevoir that will push fuel back into the rails when the fuel drops.
Its about 200.00.
Th intank walboro is about 125.00.
Dave

SDB

iTrader: (7)

Hey dave...any word on the billet microswitch bracket for the GTO yet. I need to get a WOT switch for my GTO, I have allready left the system armed and backed off the throttle once!!! Luckily no damage...

I sent back in the prototype with additional measurements and pics some time ago...tried cobbling up one and it didn't work well!!!

Scott

Nitro Dave's Nitrous Outlet

iTrader: (25)

Scott,
Just waiting on them to come back from the machine shop.Hopefully soon.
Dave

SDB

iTrader: (7)

Cool....I am geting my GTO tuned and will check AF ratio....I ran once at the track, went 12.5 @ 115 on stock tires and 150 shot (everything else stock except for homemade CAI). If I could launch on the bottle (i.e. 3000 stall converter) with tires, I bet money it would go 11.9's I am glad I have a 4100 lb car w/ driver going 115 on a little under $1K. I still need -6 timing for the 150 shot, tried -5, it was OK, tried -4 and it stumbled, detonated, and blew the dipstick up and sprayed oil in the engine compartment (and I had a spring on the dipstick to housing!). Why am I needing to take out 6 degrees from a stock LS1????

Dave, do you need a stand for a refill station IF the mother bottle has a siphon tube using the NX refill station???? How do I tell if my bottles have a siphon tube in them (the 65 lb cylinders)?

Magic Chicken

iTrader: (1)

Green Thunder

iTrader: (11)

Still a little confused on how it would work... Is there a link? Sounds like an interesting idea, but I am doubting how well it would actually work..