Still Surging (Guru's inside Please)
 

I've been fighting and tracking down an issue with my wet NX setup surging when I get to about 4700 rpm's all the way to redline (6k) for a long time now.

I have:
-checked every wire & electrical connection
-checked every hose
-changed every plug (even tried smaller gap .032)
-changed every plug wire
-bypassed WOT switch for testing
-bypassed Window switch for testing
-opened solinoid's directly
-tested w/ nitrous line in hand at pressure
-changed relays (40A)
-cleaned up grounds
-changed nitrous distributors
-pulled filter out for testing
-tested w/ only feed line (no pressure sensor, filter, etc.)

This surging occurs at all jetting levels (50,75,100,150) and has me completely stumped. I always use at least 94 octane, the o2's look good on my predator when spraying, Fuel pressure is never below 52ish, bottle testing pressure from 900-1150ish.

Anyone have any suggestions or thoughts on what I could be experiencing or over-looking?

I know this might sound stupid but where is the nozzle located at. When i had my v6 i located the nozzle before the mass air meter and when ever i sprayed it surged like a mother. If your nozzle is located before the mass air meter than thats likley your problem.

Nope, it is about 2-3 inches away from the TB.

Oh, and this is an 04' GTO.

another question, how is your bottle mounted? Nitrous is in a liquid form when in your bottle and if you have the bottle positioned where the siphon tube could be getting starved from the nitrous when you are accelerating, that could be causing a slight surge.....just something to check.

Bottle is positioned w/ the valve facing almost directly forward (off about 10*-15* to the right) and up about 15*. This happens on a full bottle also.

I have:
-checked every wire & electrical connection SO is clicking and ON fine CHECK
-checked every hose check for WHAT?-changed every plug (even tried smaller gap .032)
-changed every plug wire to new or old ones?-bypassed WOT switch for testing
-bypassed Window switch for testing during a run no window switch?
-opened solinoid's directly This one is double checking the first one good.
-tested w/ nitrous line in hand at pressure what did that look like?-changed relays (40A)
-cleaned up grounds again good
-changed nitrous distributors hmmm ok
-pulled filter out for testing during a pass?
-tested w/ only feed line (no pressure sensor, filter, etc.) during a pass?


Since this is happening at all tune ups you have 2 options. Tune up, or the something with flow, nitrous or fuel.
first what jet numbers are you running? not hp the real numbers. this surge is it something you can hear in the car and people can hear at the starting line? OR is something you feel in the seat of the pants.?
Surging in most case is dealing with rich tune up or a nitrous/fuel flow problem. And since it only does this at 4700 and above lends me to believe tune up, with nitrous or the car.
What is your timing tables, and have you logged any knock?

Sorry for all the questions but it will help me out which way to go.
Ricky

-solinoids SO is clicking Off and ON fine CHECK
both work perfect

-Hoses check for WHAT?
obstructions in the lines, leaks, loose connections

-changed every plug (even tried smaller gap .032)
running TR6's

-changed every plug wire to new or old ones?
Both (original w/ 20k on them and new MSD wires)

-bypassed WOT switch for testing

-bypassed Window switch for testing during a run no window switch?
Yes, both on a pull and hood open w/ the line off

-opened solinoid's directly This one is double checking the first one good.
both open, hold open and close as they should

-tested w/ nitrous line in hand at pressure what did that look like?
solid white full plume of nitrous all the way to redline

-changed relays (40A)

-cleaned up grounds again good
not my first rodeo :lol:

-changed nitrous distributors/vendors hmmm ok
had recieved a fill w/ a lot of air in it once before

-pulled filter out for testing during a pass?
Yes, both again durring a pass and w/ hood open

-tested w/ only feed line (no pressure sensor, filter, etc.) during a pass?
Yes, again both durring a pass and w/ the hood open

Since this is happening at all tune ups you have 2 options. Tune up, or the something with flow, nitrous or fuel.

First what jet numbers are you running?
75hp = 41N 22F
100 = not sure, but I think I stepped the fuel down 1 size
150hp = 62N 33F


This surge is it something you can hear in the car and people can hear at the starting line? OR is something you feel in the seat of the pants.?
Both. You feel it pretty hard in the car (on,off,on,off) in about .3-.4 second intervals and have had people say that they can see and hear it doing it on the track too. Also it isn't as noticeable in 1st as the rest of the gears, but I'm assuming that is due to how fast it climbs to redline.

Surging in most case is dealing with rich tune up or a nitrous/fuel flow problem. And since it only does this at 4700 and above lends me to believe tune up, with nitrous or the car.
When I installed the system all the jetting looked great on the dyno w/ wideband ~12.0 a/f

What is your timing tables, and have you logged any knock?
timing is only about 17-19* at WOT. I have only seen about 1-1.5 knock when it starts to surge and none up to that point.

Sorry for all the questions but it will help me out which way to go.
No problem, I'm in need for help since I can't track this on my own.

-tested w/ nitrous line in hand at pressure what did that look like?
solid white full plume of nitrous all the way to redline

You held the line during a pass.. DAMM thats crazy. ok back to the problem.

Have you been able to log any mis fires/ Almost sounds like a coil is going away.. the timing is a smedge low but that would not cause this issue. Weak spark would or fuel pump surge would.

HMMMMM question while you where doing your hand holding nitrous line, what did the engine sound like, clean or crappy.? did you disconnect the fuel when you did this test?

Ricky

-tested w/ nitrous line in hand at pressure what did that look like?
solid white full plume of nitrous all the way to redline

HaHa, no. Held it when the hood was open and had it attached durring the runs. :)

No. I'm using a predator and if it is missing it isn't enough to alarm the car and set off a CEL


fuel pressure looks ok based on the gauge.

sounded like it should I guess, pretty clean and then a lot of smoke from the extra fuel when I left the line on. When both lines were off it sounded fine and w/o having a jet in place the fuel looked like it spung a leak according to the gauge.

Tried both ways. Fuel flows fine out of line when it is disconnected

have you tried a different bottle from a freind or someone else.... the kickers is only at X rpm and above.
Got to be ignition system sound like it checks out...

Ricky

Unfortunately Yes

only 36k on the car. I'm hoping it isn't the coils.

I have ridden in the car several times with this problem and every time I have said it feels like an ignition issue. :-\

hmmm. OK first of all. That is alot of timming pulled out for a 100 to 150 shot.

You should be at 24 to 25* on timming.
My thoughts are this.
With so much timming pulled out you are not getting full combustion. This is where the knock is comming from.

If that does not solve the problem and you are getting knock we have problems somewhere machanical.

Now keep in mind that when you put the timming where it should be it may change airfuel since it will be running correctly.

Where is your nozzle placed?
Also make sure that the throttle blade is not making contact on the micro switch and then rotating just enough more to break the contact..

I really feel the problem is in the tune up. You have way to much timming pulled.

I have not pulled any timing. This is where it was from the predator tune.

Even though it only happens at the point of surging?

any ideas of what or where


So should I start off w/ a larger fuel jet to be safe after putting some more timing in it?

passenger side of the intake tube, ~3" from the TB plate

I had this issue when I first installed it and spent a while manufacturing another bracket for the switch to make sure this wouldn't be an issue again.

Thing is: I haven't pulled any timing at all and before the surging it all checked out ok.

OK have never used the predetor. So Im not that knowledgeable in that area. But for some reason it is setting the timming way in the wrong area.
Contact Predator and see what they have to say..

I would add a bigger fuel jet back into the system when you add the timming. Then if it is to fat you can pull it back out.

Timming may not be the direct problem. But it is something that needs to be addressed.
Let me know what you find out.
Dave

ERRR... :bang: :bang: :bang:

This is what I was going to say. In my experiance surging or some other form of misfire or other wackyness that only happens above a certain RPM is usually ignition related.

are you getting any knock?

sometimes it shows up around 1-1.8ish but only durring the surging.

is your fpss set too high? maybe your fuel system is getting taxed too much and the fpss cuts out on/off rapidly uptop. mine did this and it was the fpss.