Try another fuel noid. It may be only opening partially, and thus ok with a smaller shot, this can happen even with new noids. Backfires generally, but not limited to, as I said in your other post are the result of going lean/detonation. Be carefull though, one of these times you may not be so lucky with only minimal damage.
Robert

 

I didn't read everything, so this was probably already said....your window switch is set too low. There is too much of a load on the motor at that RPM at WOT. Up it to at least 3600 RPM's, if not 3700.

 

Ok I will try that. Thanks

 

update guys.....

The car is now worse

I even did a 75 shot...with the rpm window switch at 3900 and the intake backfired again. I took off the filter and fuel is just sitting in the bottom of the intake near the filter still...

Here are the changes I made...

1. tilted bottle upward more of an angle

2. Raised rpm on window switch from 3200 to 3900.

3. Changed plugs and put NGK BKR6E plugs in(1 step colder instead of 2)

Could it be my plug choice? It got way worse going up a step to a 1 step colder plug instead of the BKR7E plugs I was running before

My car never used to do this on a 75 shot with the BKR7E plugs

Could plugs cause fuel puddling???

 

anybody?

 

Do you have a wideband or scanner to monitor the O2s? Robert brings up a good point, it is VERY common to find a swelled plunger in the fuel noid which will limit fuel flow and at times cut it completely off....

 

you have to be having a hardware malfunction then.
I would take the nozzle out and hook it up so it sprays into a bottle. First fuel then nitrous. Check all your lines for flappers or restrictions.

You did say you checked the AF on the dyno correct? When it backfired on the dyno what was the AF ratio?

Can you take pics of your install and post the graphs from the dyno?

Did you dyno all motor when you were at the dyno? Did the car show any signs of malfunction all motor? Low on power, erratic idle anything out of the ordinary at all NA?

As far as plugs...what did your 7s look like? Any burnt tips at all?

 

time to get into an LSX??? good luck on getting this figured out.

 

Yes all of the BKR7E's had burnt orange tips

what does this mean???


Also the car never backfired on the dyno at all...only does it on the street. The car dyno'd just fine on a 150 shot on the dyno. AFR's you can see in the dyno chart I displayed below.

I also dynod all motor and the graph looks really good.

 

Here is a scan of my graph

All motor run then overlapped with 150 shot nitrous run

And this was on 89 bad gas and no bottle heater. I'd sure like to go back when its running right and see what she puts down on race gas. O well

 

Is it just me -- or does that look like it is on the lean side?

 

Yeah it does but its also after the cats....so its going to show leaner than it really is. Who knows though.

But also...if its lean...how is there so much excess fuel just sitting in the intake puddling? I pulled off the filter and there was fuel just sitting in the pipe and I had to wipe it out.

Could the plugs cause intake fuel puddling? Cause my situation got worse, a lot worse, going from BKR7E(which are 2 step colder than stock) to BKR6E(which is 1 step colder than stock)

 

you are WAYYYY too lean. It doesnt matter if its after the cats...its not gonna make you appear to be that lean. Your lean at WOT on motor as well.

If you were to pour the puddled fuel in your intake into a cup...how much would there be? Keep in mind...a little fuel looks like alot when its spread out. Its not unusual to look into an intake after a wet nitrous run and find the intake coated. It would be unusual to see several ounces of liquid pooled though.

IMO you have tuning issues.
Dont take this the wrong way...but its very difficult to get an accurate understanding of whats happening here. because it sounds like you dont have the basic understanding you need to be running this 150 shot on a 3.0 engine.

There is no such thing as "who knows though" when dealing with nitrous. All parameters must be known and understood if your going to run a 150 shot on a 3.0 liter motor. Thats not a small shot all things considered.


That AF graph is atrocious. At your peak TQ (your most detonation prone rpm) you are at approximately 13.5 to 1 AF ratio. Thats WAYYYYY tooo lean. And likley the cause of your backfire.

It appears you have a fuel flow issue.. What that issue is I have no idea yet. It may be simple jetting. You appear to have a weird AF on motor as well. It starts out too lean then goes richer. It does something similair on juice....but eventually gets rich enough. Something isnt operating properly or is not set up right.

Can you take pics of your setup...specifically the fuel side from where you have it tapped off the fuel rail all the way to the nozzle.

Again...what fuel pump are you using?


first thing I would do is jet way up on the fuel side. You need your AF ratio to be no higher than 11.8 to one within a few hundred rpm of nitrous activation. Right now it appears to be around 14.5 to one or more. Dangerously lean. Im surprised the motor hasnt had a meltdown yet.

Im not giving you a hard time. I want you to get this resolved so you can enjoy it. But hopefully youll come away with a better understanding of how engines work with nitrous and whats important.

 

Okay...my car was completely stock for that all motor pull with just an intake and exhaust. So why would it be that lean straight from the factory? The cats HAVE to be showing a way leaner #...because that car is stock on the all motor pull

For the 150 shot it got a Twin turbo denso fuel pump plus a hotwire running to the battery that supports 700rwhp.


When I said who knows tho, I was referring to the "cats" afr since it can VARY so widely. Its not like I'm a total newb with nitrous. I feel I am doing ALL the right steps here. I mean read my first post I made, I have the right stuff.

How can it be tuning? There is nothing done to my car but an upgraded fuel pump, intake, and exhaust

 

Guys...here is my STOCK dyno graph with just intake and exhaust.

Now look at the AFR...see how lean it still shows? The dyno graph I put on before this with the 150 shot has a RICHER afr than this one. Meaning my car is getting MORE fuel when the nitrous hits. My guess is the real AFR before the cats on this thing is in the high 10's low 11's. The car is getting MORE fuel and is MORE RICH than the run on the factory tuned engine with NO MODS but intake and exhaust.

 

Also...here is the picture of the plugs I just pulled out of it

BKR7E(2 steps colder than factory)

 

it appears you are lean from the factory. I have dynoed many mnay cars with cats. Its affect on AF ratio is negligable. When tuning AF for best power NA you will arrive at the same ratio for best power as a non catted car. or atleast darn close. So you really have to assume its lean. I belive you would pick up power all motor with a tune as well.

I think you should rejet something like a 100 shot with a 150 fuel jet and set your rpm activation to 4000 on a 6500 off for testing. Then branch out from there.

Its hard to tell whats up with your plugs from those pics. They are a little too blurry. They arent melted. And some portions almost look like its rich. But the tip looks ok. But unless you pulled them just after the nitrous run it would be hard to tell much unless they were melted or severely damaged. However they do have some discoloration. What gas are you using again? brand and octane?

What I dont like...is that even though you start off very very lean...by 6300 rpm you are about where you want to be on AF ratio. So I am hoping by going with a 100 nitrous pill and a 150 fuel pill that you dont go tooo rich in the uper rpms. That would be an indication you have some other issue as well.
Can you snap a pick of your install? With a close up of the nozzle?



The dyno wideband shows lean. I would take that to mean its lean..and nothing else.

Good luck man. let us know how it comes out.

 

I am running VP 109 unleaded(highest octane unleaded fuel) mixed with 93 octane. So Im guessing around 100 octane I have for the full tank
Here are some pics of the set up

 

I went and special order some 3 STEP COLDER iridium plugs by NGK so they will be here tomorrow....im hoping this does it. If not....I will try upping the fuel jet like you said.

 

it is not your plugs, you need more fuel and a tune