KartaRailed

Need a bit of advice from the guys who are tuning for nitrous. Heres whats going on.

If i'm doing a thrid gear pull, logging and all that mess, I arm my nitrous, and spray on a WOT (Wide Open Throttle) switch. If I arm and then punch it, I get excessive counts of knock. The map in the car was literally running about 2 degrees of timing with stock boost levels and an 11.5 AFR, on sonoco 116 straight with no 93. It sees anywhere from 15 counts of knock up to an all time high of about 30 where it made some unhappy noises. Now just doing this, it would tell me that my car wasnt ment for nitrous and I should stop trying to spray this 100 shot, and go back to the 50. Now, on the other hand, this is what makes me question what is going on. If I hit it, then arm the nitrous switch, I get no knock at all, aside from a few scattered hits of 1 or 2 counts. Someone explain to me why this is happening, because I have no idea. Someone told me that evo 9's have a lean spool feature that could cause it, but they were not sure if 8's had that same feature. Any information from nitrous abusers or professional tuners would be greatly appreciated.

turboracer

What rpm are going full throttle with nitrous on? If you are in a very low area say below 3000 you could knock pretty bad with a 100 shot. I use a window switch to set on rpm at 3000 and off at 7000. I get about 3 to 5 knock counts when the bottle hits sometimes. It doesn't seem to make any problems for me though.

ExViTermini

iTrader: (25)

With the wet kit you would think it should add enough fuel to take over...but I'm guessing that the turbo is spooling at the same time, and the ecu shoots for a 12 or so in spool up. You need to richen up the 2500-4000 or so parts of the map below your peak load, say you full load at 220, u need to richen 120 and upwards, b/c thats where your spray hits.

KartaRailed

Spray starts at 4000 rpm minimum. Richening up the lower load cells sounds possible, but the data logs dont show any excessivly lean spots in the AFR, even right at the start of the log. However, it does spike timing when the spray hits, somehow one run it hit 37 degrees of timing advance, right as the spray hit, that didnt like it very much.

evoRS06

iTrader: (1)

this is my thoughts, think of what nitrous does in your cylinder, it fogs and then the nitrogen sep. from the oxygen and basically acts like forced induction with out robbing power to work. what it seems like your seeing in the scenerio of arming then punching it is a super lean condition b/c your ecu is fueling for your normal boost and its getting way to much air causing your load to spike high, and in the other scenerio its already spooling the turbo so the load your hitting isn't as high. i mean check your load in the areas in both scenerios and please let us know what your seeing, cause i'm just speculating here. i hope this helps.

KartaRailed

The thing is, that with a wet kit, its supplying its own fuel, the AFR's never show a lean condition logging with the zeitronix, and if it were to go to an extremly high load cell, than it would drop timing, not advance it a rediculous ammount.

evoRS06

iTrader: (1)

well through some logs on here in both scenerios and let us take a look at what your ecu is doing. and your right it would pull timing, maybe your spiking high knock and the ecus algorythm is causing it to carry through the rpm range, i mean is the knock steadly decreasing through the rpm range? b/c the ecus algorythm stair steps.

KartaRailed

I refuse to stay in it when this happens, the knock is so excessive that I would be afraid to stay in it. Ill get some fresh logs when I get my cable back from my friend, but I have some other fixing to do, as my perfect pump gas AFR has suddenly decided to disappear from the 11.9-12.0 it was at, and is now going from about 12.2 low to 12.6 up top.

black E

iTrader: (77)

the same thing happens to me if i try to spool the turbo on 5th gear from a low RPM (2000-2500).For some reason it knocks bad when i do that but i can do the same thing in 4th all day and not Knock even one's. I think it's got some thing to do with the way the engine it's loaded or the amount off load the engine is under when the air it's moving so slowly. ( i mean actual engine loan not ECU load.)

codgi

iTrader: (22)

Do you have lean spool enabled? And are you hitting the same load cells in 5th and you are in 4th? Sounds like a combination of the 2 is whats causing this problem.

KartaRailed

Question, do 8's in fact have a lean spool feature?

Jeff_Jeske

iTrader: (66)

Odds are its mechanical/false knock.

If you are running reasonable timing and AFR on 116 octane you shouldn't be seeing any real knock.

I would check downpipe to oil pan and tie rod clearances. I'm guessing the initial torque of full boost combined with a large shot are rocking the motor pretty good.

KartaRailed

If it was false knock it would be the twin plate, but that isnt the problem when the entire car shakes and a lound brap brap brap comes from the motor. Im thinkin its the lean spool more and more. If I could just get my damn cable back.

Jeff_Jeske

iTrader: (66)

If the entire car is shaking and misfiring then it could be that you have reached your load cut or you are blowing out your spark. Have you inspected the plugs?

Lean spool isn't going to cause that.

codgi

iTrader: (22)

Yes and it is enabled by default.