I have been posting about problems with my DPI since I installed it a week or so ago. This time the problem is very defined.

I am going to re-list my stuff again to narrow down possibilities:

NOS direct port wet
2 steps colder NGK plugs (copper) gapped down to 35
stock 190L fuel pump (down graded from a 255L Walbro)
Stillen FPR set to stock FP
NOS purge
25/14 jets (N2O-Fuel)

Ok, the problem is that as soon as the system is engaged (@WOT) the car falls on it's face for about .5 sec and then jumps back to life and pulls hard. Based on both the EGT and A/F gauge, once engaged, the mix is fine, even running a little on the rich side but that's ok. As I said, when the car pulls--it pulls hard. It doesn't stop pulling from there until I tell it to. The problem is every single time no matter what gear I do it in. The only time I have not had as much, still some there, is at the extreme top end, i.e. if I engage it in top gear @ WOT @ 100+mph.

I think that one of two things could be causing this. The fuel solenoid is opening before the N2O solenoid (eventhough they are right next to each other and connected to the same wiring) and thereby flooding the car for a split second or blowing out the spark.

Let me know any ideas you guys think it could be.

 

that sounds like it could be the problem.

 

The red intake manifold looks cool Hmm...how did you come up with that jets match up? You are brave...That's an aggrassive match up. Don't ever let that bottle pressure creep above 900psi with that small of of fuel jets. I think I ran a .014 fuel jets with .020 nitrous jet and it was running lean. With a .025 nitrous....wow.. Brave. Is your fuel hard lines longer than your nitrous lines? I can't really tell from the picture. If it's, that's the problem. Actually, most people with direct port prefer the fuel lines to be a bit longer than the nitrous lines. 1. To prevent lean condition. 2. The delaying of the nitrous flow will give your car more traction.

 

That's the thing, with a 24/18, 22/18, 22/16, 24/16 match up the car ran like crap. It just sputtered and coughed, like it was flooded the whole time it was engaged. I moved up to 25/14's and it stopped acting like it was flooded AFTER the initial hiccup. According to the gauges, once the car gets over the falling down part it takes off hard. According to NOS tech line, they seem to think that I should go back to my High volume Walbro pump because they think the problem is initial fuel pressure drop at engagement.

 

These are the same guys that tell us to run a 70-shot dry kit with stock plugs and fuel pump

 

I know. They were also total *icks about giving me the combo for the jets anywhere near 100+ wet or dry. They said that the car would not hold it..

What do you guys think I should do? If it weren't for my lousy 60' times, I would just leave it and deal with it. I know the car has low 13's in it now, just can't do it with 2.5 60' times on street tires. What can I check? Come on guys, you guys are the experts at this, please help? Everyone around here is totally lost as to what to try next.

 

Dude, I know this sounds bad, but try posting your problem on some of the Honduh forums... It may not be a max, but a lot of those guys have been using direct port for a long time, and may be able to help... just an idea...

 

The NOS tech line is wrong. You don't get an inital fuel pressure drop when the system is engaged. It's actually the opposite if anything. The pressure stays high at first because the rails and lines are already charged with 3.0 bar of fuel. Take all your foggers off and have them srpay into the air and you'll see what I mean. They start big and fall off a bit if you're running a big shot. It's the same thing as popping the cork off a wine bottle or opening a can of shaken pepsi.

And yes, the fuel does usually get through the fogger before the good cold nitrous liquid does. These systems were initially designed with a 5 to 6 psi fuel pressure in mind. But both solenoids do open together and at the same time.

And whats this crap they said aboutt he car not holding it? Don't pay any attention to those people. They're used to dealing with American made junk and have no clue as to what Nissan engines are capable of or built with.

You may have to build some type of 1/4 or 1/2 second delay into the fuel solenoid to solve that problem. You can make a timing device via capacitance discharge and another relay.

 

What about getting a progressive controller? Or ghettoing it and putting a shorter feed line from the N2O solenoid to the distribution block before the jets?

 

Progressive controller? HA! And you think you've got problems now?
Yes you could make the nitrous feed shorter to the solenoid but I am not sure if that will help. It definately is worth a try though.

 

Ok, I follow the electrical delay on the solenoid idea. Now how in the world would I go about building one? My buddy bags game me some links to some companies that have electrical delays, and I'm researching and seeing if it would work for my application. The one your thinking about, How would you build it? How would you control the amount of delay it would give me?

 

The capacitance discharge rate is determined by the capacitance of the capacitor, the voltage and the resistance of the discharge. What you do is setup a charged capacitor that holds open a relay. Once you arm and switch on the nitrous the current is cut off from that cap. When the cap no longer has enough current to hold the relay open the relay closes and supplies power to your solenoid. You can wirea potentiometer in series with that capacitor to control the current flow to regulate the time at which the event takes place. Of course you ahve to find the correct size capacitor and the right kinds of relays. This small project could turn into a spaghetti nightmare if youa rent careful.

 

actually, with the stock pump, there is a pretty big pressure drop right as the you engage the nitrous. try this: go about like you're going to do a test run. you floor it and the car stutters. while the car is still stuttering, get off the gas and turn off the ignition immediately, and pull your plugs. see if they indicate rich or lean.

 

i saw your other posts.. this one was the one I wanted to reply to.


I know very little about nitrous so please bare with me.. I am trying to help jaime out..

So what about putting a time delayed relay in the mix.. for example..

setting up a delayed relay to power on when you nitrous arming switch comes on and then setting it to time delay when the wide open throttle switch, jaime uses that, so when he goes WOT it has a delay of .15 sec, for example, delaying power maybe to the fuel pump? or maybe a regulator? or something else?

Does this make sense or will is it possible to blow your motor up since You may have a fuel starvation problem?

Again just trying to see if I can help

thanks

 

That is what I am saying but you would need to delay the fuel solenoid. And that could get you intot trouble quickly if it doesn't come on when it should. To be safe for now you guys should do what SX7R mentioned and check the plugs. He's right, thats the best way to check the mix if you think your A/F is lieing to you or isn't quick enough.

 

Ahh.. ok thank you for helping to clear that up for me



and yes Nitrous answers fro sx7r are always a great thing..thank you

oh and I am just trying to get answers..no action yet.. I want to fully understand what I might do. so I understand electricly what he needs.

 

Ok, I'll try that....didn't you tell me to go back to the stock 190L pump? Would now going back to the 255L Walbro help?

 

nono, i said the best choice would be to get the walbro 190lph - like the one tony runs. i doubt the stock pump even flows at 190lph. i had mine running on the 255; however, i had to lower the fuel pressure pretty low.

 

You dog!!! you made me change my fuel pump for nothing!!! I'm just kidding, I guess I misunderstood. I went back to the stock 190 pump. You think maybe that's part of the problem, the stocker can't keep up? Should I try going back to my walbro 255 and lowering the fuel pressure to like 25psi like you said before?

 

you have a fuel pressure gauge in the cabin right? if so you should be able to see the massive pressure drop when you engage nitrous while on the stock fuel pump. it'd be a lot better trying on the 255lph pump than the stock one - more fuel is better than not enough. at first i tuned mine using the walbro 255, i got frustrated so because it was running so rich, so i swapped back to the stock one and that pump just didn't flow enough(big pressure drop). then i went back to the walbro 255 and lowered the fuel pressure and finally got it to work decently - not perfectly, but it worked. so your best bet would still be to get the 190lph walbro.

 

What did your do with the 255 and lower fuel pressure? How did the car run? What do you mean by not perfect but it worked? Tell me, cause if it's better than what I got now, then i'll try it until I can order a 190 walbro.

 

I do have the gauge but it's not connected because I took it out to send back to AutoMeter on the recall and never did. I think I'm just going to hook it back up and just forget about sending it back.

So, to answer your question...no, but my butt dyno still works...

 

maybe I should test drive it

 

it worked as in it didn't stutter, but not perfect as in it was still pretty rich even with .014 fuel jets and lower fuel pressure. so basically, if it hadn't been so rich, it would have been making more power.

 

That would totally solve the problem because it would probably blow up....

 

maybe but man it would be cool

and FUN

 

Well, since I have to run tommorow night again, I think I'm going to try and put the walbro 255 back in until I get the 190. Did it run strong or did it miss? When I first ran mine with the 255 pump, it was running really rich and it would cut the car off and stuff, but I was also not running with the .014 jets in (I had the .018's in). Maybe I can run it with the 255, lower pressure at the regulator, and maybe try and heat up the bottle good to get a little more pressure up at the N2O jets to compensate. You did say that you ran your FPR down to like 25 psi didn't you? You think that will work a little better?

On a side note, where can I get a 190 walbro pump? I bought mine a while back and don't remember where I got it.

 

Why don't you go with me tomm night? That way, when I do blow up, you can tow me back....

 

Which would be the best choice, the Walbro 190 or 255 for a wet kit? How about a dry kit? Regular or high pressure version pump?

If I run the wet kit, I want to keep the base fuel pressure as close to stock as possible, so I should get the 190, right? Regular or high pressure?

Thanks.

 

www.autoperformanceengineering.com

 

Thank you, except one thing- Didn't we order the one for like a mitsubishi turbo or JDM something? Does anyone have the part number for the 190 walbro pump that is plug and play on our cars?

 

They have a 190lph maxima replacement pump, I remember seeing it on the website...

 

wet kit: 190lph
dry kit: 255lph hp

the 190lph does not come in a high pressure version

JAIMECBR900: contact tony(1MAX2NV). he's got the 190lph.

 

okay jaime i know your in the atlanta battle of the imports but check it. go to another dyno and see if they have the air/fuel o2 sensor hook up. that way you can see exactly whats happening when you engage nos.

am i in way left field here?

have you postively(sp) identified the problem as too much fuel?

 

Very good idea broham...but guess what?....I found and fixed the problem...you guys ready for this?...

It was the drop in fuel pressure from the stocker pump. After thinking about the posts for a little while and trying to make common sense of it all, I decided to re-install my 255 walbro pump. I've installed and re-installed that pump so much here lately it took me about 15 mins last night to re-do it. I took it out for a spin and all I can say is DAAAMMM******. Now it engages the second I hit the switch and pulls hard.

Now the problem I see already I'm going to have is going to be traction . It lights the tires up even if I wait to engage deep into 1st gear/2nd gear.

I just need to get me a dedicated race car and be done with it...

 

Just for follow up.....




http://forums.maxima.org/showthread....hreadid=146416

 

Thanks sx7r.