whats wrong? stuttering with direct port DP - Nitrous Oxide Forum

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whats wrong? stuttering with direct port DP
Sunday, August 05, 2007 5:24 PM
the car runs fine when not using nitrous and all I can think is either fuel is an issue or my jets are wrong...

I have pretty good fuel pressure generally, running the GM supercharger with stock pulley. Colder plugs, MSD DIS2, MSD 8.5mm wires, MSD mitsu coil pack conversion on a z24 with the LD9.

When spraying, I only spray over 3K, the car stutters and pops until you let off the nitrous. The supercharger sees 7psi, the EGT goes to 1600 degrees F, and the wideband is off the chart, if its off the chart lean or rich I don't know, I believe its off the chart rich cause I changed out the fuel jets to a lower number and it still did it. I tried adjusting the fuel pressure to lean it out some and it still did it with no difference. I checked the solenoids and they are firing properly.

The jets I am using are

Nitrous - 20
fuel ------ 14 and 12

Anyone have any ideas?

thanks

Scott





Re: whats wrong? stuttering with direct port DP
Monday, August 06, 2007 6:02 AM
You know, I forgot to mention that I am also using an 8:1 FMU... maybe its pushing too much fuel thru everything??? I forgot to disconnect that and right now the nitrous system is screwed unless I can find the 20 jet that I lost down the side of the engine



Re: whats wrong? stuttering with direct port DP
Monday, August 06, 2007 8:33 AM
How many injectors?
What bottle pressure?
What fuel pressure?


For 900psi and 48psi, .020"N and .011"F = 18hp

sig not found
Re: whats wrong? stuttering with direct port DP
Monday, August 06, 2007 8:48 AM
Using the GM supercharger injectors x 4
then just nitrous wet shot nozzles x 4
fuel pressure I am not entirely sure of, I just got the fuel pressure gauge and haven't had a chance to take the fuel rail apart to thread it in. Besides that, with the 8:1 fmu I don't know how much more pressure that would add exactly

For fuel I am running an MSD external pump (which does make a huge difference) and the 8:1 fmu and of course 93 octane

I couldn't find 11 jets so I just figured I would go a lil rich with the 12s and bought 14s to start off so I wouldn't blow it up. It seemed to actually almost run a lil better with the 14 fuel jets tho

Bottle pressure 950-1000 psi

thanks




Re: whats wrong? stuttering with direct port DP
Monday, August 06, 2007 9:28 AM
read your plugs... if they're black, too rich... if they're white, too lean.

I'm guessing too rich for the simple fact you havent blown @!#$ up yet.



Built, bottled, ready for 11s. 14.446@93.74mph, 1.848 60' N/A.
Re: whats wrong? stuttering with direct port DP
Monday, August 06, 2007 9:51 AM
alright, maybe I will do that tonight when I get home from work



Re: whats wrong? stuttering with direct port DP
Monday, August 06, 2007 2:10 PM
I have a .020 jet if ya' want it.I need a .026 for my fuel



15.2@89mph 2.171 60ft. 9.830 1/8 R.I.P. "LULU"
Re: whats wrong? stuttering with direct port DP
Monday, August 06, 2007 3:35 PM
what nozzle is it for? Cold fuzion or NOS brand? They are interchangeable, NX isn't tho. I do believe I have a 26 jet, that would solve one small problem...



Re: whats wrong? stuttering with direct port DP
Monday, August 06, 2007 6:03 PM
It's for a Edelbrock nozzle so yeah it might not work but it just seems that all taper face jets should be interchangable



15.2@89mph 2.171 60ft. 9.830 1/8 R.I.P. "LULU"
Re: whats wrong? stuttering with direct port DP
Monday, August 06, 2007 6:28 PM
msd external pump = crap

and whats your timing, plug gap and how cold of plugs you using?




Re: whats wrong? stuttering with direct port DP
Monday, August 06, 2007 10:42 PM
Quote:

When spraying, I only spray over 3K, the car stutters and pops until you let off the nitrous. The supercharger sees 7psi, the EGT goes to 1600 degrees F, and the wideband is off the chart, if its off the chart lean or rich I don't know, I believe its off the chart rich cause I changed out the fuel jets to a lower number and it still did it. I tried adjusting the fuel pressure to lean it out some and it still did it with no difference. I checked the solenoids and they are firing properly.


well... whats your a/f reading on your wideband?/ u just said off the chart... as in like 14+ or like 10.

u say it stutters and pops.. that sounds lean... if it boggs down and looses power... thats too much fuel.

just a quick question but.....u have the gm charger and injectors.. im assuming u have the reflash?? if not, thats yoru problem.. u need to get it... if u do have it, ditch the fmu cuz its not needed as the new ecu flash is calibrated for the larger injectors

Quote:

msd external pump = crap

and whats your timing, plug gap and how cold of plugs you using?


how do u figure?? i run an external with my hahn stage 2.


http://www.myspace.com/15102113

12.5@116 2.0 60ft

Re: whats wrong? stuttering with direct port DP
Tuesday, August 07, 2007 4:40 AM
I have the reflash, so whatever timing its pulling, which I hear is a lot.

MSD isn't crap because it actually does do something, my A/F and the car running lean in boost without it on proves that.

FMU is needed cause the MSD only keeps the AF in the 13s, the FMU keeps low 12s. Wideband is in the header just before the firewall on a pacesetter header so I don't believe that could cause a miss reading. I'm not quite sure what the wideband is reading cause it only reads to the 11s (AEM FTL), but when I let off I tried to see where it comes from and I think its starts back thru the 11s to lean, but I can't be sure... I do want to try it without the FMU seeing boost maybe that will help but I doubt it...When I find that 20 jet I will give it a run, hopefully today after work...

Quote:

u say it stutters and pops.. that sounds lean... if it bogs down and looses power... thats too much fuel


kinda does both cause it definitely isn't making the power it should be.... and I think I would have blown it up by now if it was too lean... IDK

Plugs looks fine with a lil black soot around the threaded area... plugs themselves look fine.

Autolites one stage colder than stock and gap is 30 i believe... whatever the mid point on the circular plug gapper is. I believe thats stock gapping.



Re: whats wrong? stuttering with direct port DP
Tuesday, August 07, 2007 1:56 PM
Ragin:Off subject but I am bidding on a 4 pack of brand new NOS nozzles on Ebay and I am wondering
what size jets are you running,was it for a 75 shot?



15.2@89mph 2.171 60ft. 9.830 1/8 R.I.P. "LULU"
Re: whats wrong? stuttering with direct port DP
Tuesday, August 07, 2007 7:02 PM
20 nitrous, 11 fuel (if you can find it) I couldn't so I went with 12 instead



Re: whats wrong? stuttering with direct port DP
Thursday, August 09, 2007 10:34 AM
the one and only question that needs to be answered yet is fuel pressure.
.012 is rich for 50 psi
not sure what stock eco pressure is to begin with, but I would guess its 50 or higher.
8:1 FMU at 5psi with a base of 50psi = 90psi...
way way way way way too rich for .012/.020.

sig not found
Re: whats wrong? stuttering with direct port DP
Friday, August 10, 2007 11:34 AM
RaGiN Z (the fake 05) wrote:

I have the reflash, so whatever timing its pulling, which I hear is a lot.

MSD isn't crap because it actually does do something, my A/F and the car running lean in boost without it on proves that.

FMU is needed cause the MSD only keeps the AF in the 13s, the FMU keeps low 12s. Wideband is in the header just before the firewall on a pacesetter header so I don't believe that could cause a miss reading. I'm not quite sure what the wideband is reading cause it only reads to the 11s (AEM FTL), but when I let off I tried to see where it comes from and I think its starts back thru the 11s to lean, but I can't be sure... I do want to try it without the FMU seeing boost maybe that will help but I doubt it...When I find that 20 jet I will give it a run, hopefully today after work...

Quote:

u say it stutters and pops.. that sounds lean... if it bogs down and looses power... thats too much fuel


kinda does both cause it definitely isn't making the power it should be.... and I think I would have blown it up by now if it was too lean... IDK

Plugs looks fine with a lil black soot around the threaded area... plugs themselves look fine.

Autolites one stage colder than stock and gap is 30 i believe... whatever the mid point on the circular plug gapper is. I believe thats stock gapping.


the problem with the fmu is, it increases your entire fuel pressure.. not jsut to the injectors... so u might have the correct size jet or whatever for the dircect port system, BUT your fuel pressure is being increases through that as well.

what is your a/f under wot WITHOUT the nitrous....

also y is ur wideband so close? its suppose to be like 30-36" from the mani according to aems book.

are u sure u have the gm reflash?? they wouldnt let it run in the 13s.... they would have too many blown motors.

there is no reason to have the fmu if you are running the stock pully with the gm flash and bigger injectors...


back on my stock motor, i ran 320cc inejctors and a fmu. got the gm reflash kit for the eco. new map, clip, 370cc injectors... wired it in.. drove to the dealership and got it flashed.. still had the fmu in, (stock ecu would flood out without)

got on it and the fmu increased the fuel pressure too much and it would start to fall down on top end. got home.. took the fmu out. still ran a lil on the rich side but it was fine.

u shouldnt have to be runnign an fmu


http://www.myspace.com/15102113

12.5@116 2.0 60ft
Re: whats wrong? stuttering with direct port DP
Friday, August 10, 2007 12:39 PM
I'm going to nix the fmu, I found the .020 jet.

I'm thinking that maybe my stock pump just sucks and not in the good way.

I can't be positive that I have the reflash, tho the motor, tranny, charger, and wiring harness with ecu all came out of a gm show car, whats the timing supposed to look like with the reflash, I could check that with my digimoto.

Under WOT without nitrous and with the 8:1 it is reading low to mid 12s.

I was told that a wideband should be approximately 8 inches from the collector. So thats where I put it, 8 inches from the collector on my pacesetter header.

hmmmm...... maybe I mixed up my ecu's and threw in the wrong one.... I doubt it tho. I am not going to run the car again until I can tap the fuel rail, went looking for the correct tap yesterday and couldn't find it (went to 5 stores).

IDK, once I know what my fuel pressure is at I will be a little happier. Maybe I will throw my stock ecu back in for a minute just to see what the difference is...

at the moment I am just stumped.

I agree tho, I shouldn't have to run the FMU




Re: whats wrong? stuttering with direct port DP
Saturday, August 11, 2007 12:29 PM
i suggest making a short run then stop remove the plugs see if the are black or white . black rich white lean of course . next if they are black i would remove the lines coming out of your distribution block with the car off press the button see if you are getting nitrous to the jets . also check the jets there not clogged and the fogger . if its lean just do the same but on the fuel side . check the basics it shouldnt take but 30 min to this and save alot of headaches . when i run of of nitrous he car will bog and stutter this could be your problem a lack of nitrous out of the jets . also just for the sake of asking make sure your jet sizes are right your fuel jet sounds to big .


13's or blowning it. wayhttp://i39.photobucket.com/albums/e175/slowfire99/100_0463.jpg
Re: whats wrong? stuttering with direct port DP
Saturday, August 11, 2007 1:15 PM
yea, I plan on doing that, I just want to know where my fuel pressure is first. I can't find an NPT tap anywhere around here. I tried, pepboys, advance auto parts, autozone, sears, and lowes. The problem is they all come in kits, I have two kits already, an SAE and a metric kit. I don't wanna buy all my taps all over again for no reason just for that one. So I have been online trying to find them and strangely enough the cheapest I could find it was on snap-on's web site. They don't charge shipping on orderes below $500 so it should be here in a few days.




Re: whats wrong? stuttering with direct port DP
Saturday, August 11, 2007 3:13 PM
Re: whats wrong? stuttering with direct port DP
Saturday, August 11, 2007 6:07 PM
at 34 bucks from JL, I think I will stick with the 7 dollar snap-on tap... with free shipping! FTW!

thanks tho




Re: whats wrong? stuttering with direct port DP
Wednesday, November 07, 2007 4:11 AM
So Scott,did you ever get things worked out?



15.2@89mph 2.171 60ft. 9.830 1/8 R.I.P. "LULU"
Re: whats wrong? stuttering with direct port DP
Wednesday, November 07, 2007 4:43 AM
ummmm.... welll...... I bought the tap........ thats about it.... I bought an LS1 for my Datsun and I also bought a house so thats where all my time and energy are going these days (into the house, the Datsun gets no love either). I haven't driven the car in two months, tho I was just thinkin about takin it today (the whole no heat thing kinda kills that idea) but no I haven't done jack. I did buy a smaller pulley for it tho, sitting on my kitchen table.




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