gregrob

iTrader: (8)

My 99 just has few bolt ons and a 150 shot.

It goes lean when you first spray then recovers. Weak pump?

I already have a 255 and hotwire harness I need to get installed . Just curious if its common. Stock pump has 107K

soundengineer

iTrader: (16)

it all has to do with the way you get your fueling...
does it come off the rail at the schrader valve? or out the end of the passenger side on a set of aftermarket rails(which is really what you want)

also, it is common for the fuel side to get there later...nitrous moves a lot faster than gasoline

also, are your lines equal lengths and sizes?

theres lots of variables...inital Lean spikes are normal on a wet kit...but they can be eliminated with a well planned system...
you may just need a delay timer to do a brief delay on the nitrous side...and were talking less than 100ms...

as an example,on my car...being a direct port and a dry kit...
the injectors get there before the nitrous does... so I have a rich spike...
43ms delay gets me back to dead even..

gregrob

iTrader: (8)

Stock rails / schrader valve / equal length -4 lines...

I'm not gonna get fancy with timers on it. Ill report back after I do the pump

camscam02

iTrader: (21)

are you seeing a lean spike on an air/fuel gauge? or is the car actually nosing over at hit, popping etc?

soundengineer

iTrader: (16)

swapping pumps will not help...
you need different rails and a regulator return system
by pulling from the schrader valve, you get a big pressure drop on one side and not so much on the other

I've logged both sides on a wet system with the schrader valve feeding the fuel side...
I was almost a full point leaner on the drivers side because because of pulling fuel from the schrader valve...and I had an upgraded pump

at a minimum.. you need aftermarket rails, and pull the fuel out of the end of the system so your pressure drop will be even and not one sided.

in from drivers side like normal , across the rear, up to the front, then out to the nitrous solenoid..

and you will still have a lean spike at first because Nitrous travels faster than fuel...

gregrob

iTrader: (8)

Wideband goes17+ then recovers to 11.9ish if i stay in it.

gregrob

iTrader: (8)

I respect your experience but you realize Im only spraying a 150 shot right?

How many thousands of people do that without issue? Its just a DD and won't ever see more spray than that.

I sprayed a 175 off the rail in my LT1 and never had this issue.

soundengineer

iTrader: (16)

I was having issues in my setup with the same thing, I was on stock rails, and a 150 shot as well when I saw the issue
was using a Racetronix pump, had even length lines...

I can guarantee that with any pump, it will have a lean spike just from coming out of the Schrader valve...

and if you do a search, you will find that many many many many people talk about how you will have an initial Lean spike on a wet shot.
some compensate by making the fuel side shorter and the nitrous side longer to get them to hit at the same time

it is a common issue that can only be solved by a proper fuel setup and properly designed system.
generic kits are not ideal for any car..

gregrob

iTrader: (8)

Its a nitrous outlet plate and TNT system.

I can try a shorter fuel line but I'm not doing after market rails on this. Ill just quit spraying if I have to. I already have one race car lol.

Thanks for the feedback

soundengineer

iTrader: (16)

and the LT1 comes stock with a Return style fuel system with the regulator in the proper place after the rails......
which is why you didnt have the issue on an LT1...

a properly designed fuel system for the nitrous

sweet99ss

iTrader: (41)

Just think about all the people spraying a 150-175 shot that don't even have probably have the crap you have on your kit and never have problems. I know people who have put on kits and ran them for years not even checking plugs or anything. Not saying it's right I'm just sayin

gregrob

iTrader: (8)

I agree, that's why I know it should be able to work without over complicating things. This is my DD that is getting a baby cam and 243s and ill probably turn it down to a 100 shot.

sweet99ss

iTrader: (41)

That's how I am. I just have it to run when I race and don't spray it for to long...

soundengineer

iTrader: (16)

so you are willing to do a time consuming fuel pump upgrade but not willing to do an easy fuel rail upgrade??

Just swapping to a set of Nasty Performance Rails...with a regulator and a return line using your existing evap line for the return...will make quite a difference on that lean hit...
Nate even sells a Kit with all the fittings...will take you less than an hour to do the upgrade


the fuel pump wont make any difference...the regulator is in the wrong spot with the stock rails to be able to help the problem

gregrob

iTrader: (8)

Yes I am. I'm not doing after market rails on this car. Fuel pump is 1/2 hour and just as reliable as OEM.

soundengineer

iTrader: (16)

again... you want to replace the piece that wont fix your problem...but you wont replace the part that will fix your problem...?

sounds like a stupid plan to me...

87silverbullet

iTrader: (11)

I understand what you are saying to gregrob but he is not going to replace the rails and all that because guys have been pulling from the rails on ls1's since they came out and have been running fine all these years.

Hell, Carter01 pulls twice this much from the rails on a Walbro pump. LS1 style fuel return.

camscam02

iTrader: (21)

He's gonna need the pump regardless because of the fuel volume needed. Now you will get a lean spike because of the differences of pressure between fuel and nitrous. It just depends how long it goes lean for... There are obvious ways to combat this but it just isn't going to go away. Equal lengths same opening time 900psi gets there much faster than 60... trying to minimize that time is what you need to do

and yes you can pull plenty of fuel off the stock rails if needed... been there done that

gregrob

iTrader: (8)

Exactly what I'm saying. I already have the pump so its going in. I will shorten the fuel line to minimize it, and let it ride...

87silverbullet

iTrader: (11)

There you go, problem solved.


Next lean spike thread please.