here are some screen shots, got a real nice kick down low with the 75shot, i am running a 100 fuel jet just to be on the safe side and it looks like it might just be needed. pushed the stall from 2700 up to 3500. probably go out and get a couple of more runs today to back it up and maybe bump it up even.

got 2 problems, the first is that lean hump, i did a few short runs and it was there every time, anyone got any ideas? only thing i can think of is maybe the fuel that is sitting in the line on the way to the fuel noid is boiling and i get a little air in there, once it gets flushed it goes back rich, i will do a nice purge next time and get some fresh fuel in that line. anyone got any other ideas?

other problem and i may start a new post about this cause it is kind of serious. the truck when warm will just stop running. i was loging with efi live and the wideband and all i see is it goes way lean and then dies, it typicaly happens after a few hard runs. i am prety concerened what will happen if it tries to do this when spraying. it did this last year and just kind of went away, now it is back, seems to be a temp related thing and just went away cause it was cold. it compltely dies or tries to die, every cylinder is not geting fuel or spark all at once the way i see it, i can be going 50mph and it will stop running. wideband shows lean but either loss of spark or fuel would show lean on that thing. i have a new pcm and motor since last year when it did the same thing. everything looks ok on the efi log. hmm

anyway, prety happy with the time for a 75shot, it was a little warmer last night too.

 

my truck died under a load on spray 1 time, i had hpp3 tuning in it and sprayed 100 running down the highway about 85-90 and it died....when i got it home i checked the plugs 3 of 8 were done. changed the plugs and took the HPP3 tuning out but left the shifts and all that and it ran fine.

 

Have you considered a separate fuel system for the nitrous.You could do it with a cheap electric fuel pump and use bigger fuel jetting like a low pressure carburated system.It's probably a good idea anyway if you plan to spray with the turbo.All it would take is a hot wire run from the arming switch of the Nitrous system to an electric fuel pump,you could probably tie into your truck's fuel return line and keep everything under the hood.You could put the fuel pump and fuel soleinoid togather and shield them from engine compartment heat in some manner.

 

Nice little boost in your 60' time. Makes a world of difference.

With a new PCM, I have no clue whats going wrong with your truck. My first impression was a gremlin in the tune, but if it did it last year on the old PCM, I have no clue. Yeah, no fuel would make it show lean, but no spark would make it show rich. Is sounds like an abuse function. Basically shut down fueling. I seem to remember reading about the differnet abuse modes and your description does seem to fit the mose severe one. Have you ever felt it go into limp mode where the throttle just idles along with no response to the petal?

 

i have seen the abuse mode/reduced power mode. i dont think it is that. it has will die on me going 40mph, completly die. the maf is still reading, map looks ok. every thing looks ok.

i am 99% sure a misfire or no spark will show lean,i have seen it before on other cars. i know it doesn't make sence since raw fuel is going into the exhaust but so is alot of oxygen meaning not enuff fuel to complete the burn meaning lean. 02's read oxygen, not fuel.

i got some 125jets in, thinking about going got a test drive

 

Probably not what you are dealing with, but I found this:

Fuel Cut OFF Mode
The fuel cutoff mode is enabled at high engine RPM, as an overspeed protection for the engine. When cutoff is in effect due to high RPM, injection
pulses will resume after engine RPM drops slightly. Also no fuel is delivered by the injectors when the ignition is (off). This prevents dieseling. Also, fuel pulses are not delivered if the PCM does not receive a CKP signal, which means the engine is not running.

 

I've got a fuel cell w/ an inline pump and I get a lean spike when the nitrous hits. The pump I have will run a couple of gallons out of the cell in a few minutes. I think the nitrous hits before the fuel has a chance to mix w/ it.

 

With regards to the lean spike at activation:

I have experienced the same things but only in wet kits. As far as I can tell it is a simple fact of delivery speed (pressure.) I have still seen this with systems with complete stand alone nitrous fuel cells - I have played with both bypassing high pressure fuel delivery and standard low pressure (typical rental car "hi-power" installs.) I have noticed that the bypassing system will tend to minimize the lean spike, however, fuel heating becomes an issue with small fuel cells (1.5-3 gallon.)

As far as the dying:

I have only experienced similar things with 03' tune vehicles. In some nitrous play in a rental car I noticed that after a heavy run and then an immediate slow-stop things are normal, but the Grand Am after a good 150 hp run and sustained freeway speeds was sluggish and felt like the vehicle died from the spark being extinguised. Unfortunatley, these runs were more recreational than for real testing so no data aquisitions were made.

 

i understand the lean spike at activation, look at that wideband chart, i didn't even get a lean spike right off but i didn't purge either so that is probably why, i got the lean spot later, like a full sec after i hit it. i wonder if it is some kind of cam interaction? the cam is definately out of it's sweet spot at that rpm.

that problem with the 03 grand am sounds exactly like what i am seeing, runs fine thru the run, quick stop and still no problems, usualy a minute or 10 later and it start acting up, 5-20 minutes later and it is all fine. 03 problem huh? need to fix that, one of these days i am going to be stuck in the middle of an intersection or something and that would suck. i am going to start loging the crank position sensor and see if maybe the signal is geting droped or something, that ever it is it is a complete on to off failure, no missing or sputering.

ran the 125jets last night , talk about major wheel spin, it wasn't completely dry out. i also saw more knock retartd than i like to see and the a/f ratio looked just like the last run, lean spot in the middle of 1st but pleanty rich everywhere else.

now for the numbers, i will repost the screen shots up top to show the new run but it was an 11.99 at 116.9mph 2.01 60', prety cool that i drop .1 on the launch and pick up .2 in the run. i think with a dry road i will be seeing 11.7 or better gtech's

for what it is worth the best gtech i ever saw in my lst truck was an 11.7 at 114mph , i am prety happy that i am at that mark all ready and have no forced induction(yet)

 

About the lean spike... could you take the fuel noid off of the window switch altogether, and leave the nitrous noid hooked up to it?