I haven't really sprayed my car much since the cam install in February/March, but did once or twice and it was fine. My fill is pretty old (~5-6 months), and the past few times I've sprayed, it's fine the first time, then after that when I spray it, it pops really bad out the exhaust and falls on its face.

My MSD timing is the same, and I changed my plugs (NGK-R 5671-A7s as per Lloyd Elliot's recommendation), gapped to .035. When I pulled the old plugs (Autolite 104's), it looked like cylinders #2 and #4 were the only ones showing significant signs of detonation. I pulled the intake off and sprayed with the nozzle pointing in the air, and it sprayed fuel all over the place, so I know it's getting fuel...'

Is it possible that my fill went stale or something? Or does it just sound like it's not getting enough fuel?

BTW, this is on a 100 shot, jetted to NX specs. I have a Walbro 255 fuel pump as well.

Thanks for reading, all help is appreciated! I wanna have some fun with this thing!

 

Id play with the timing a bit and see if you cant get it calmed down

 

Do you have any idea where your airfuel is? You should be about 11.8 on nitrous. If you do not have a way of monitoring airfuel or reading spark plugs get with me and I will teach you how to read spark plugs.

For a 100 shot 7s are to cold in my opinion. I would go back to the NGK tr6s. If you have a cylinder burning hoter than the others you may run a 7 in that cylinder. Or just running the system alittle richer over all to protect the cylinders you said were running leaner.

Lets go through a process of elimiations and I will help you resolve your problem.

The info I need starts here.
Bottle pressure?
Airfuel?
Total Timming N/A and on N2o
What does the bottle way?
If you open the bottle is it a steady big white cloud.
Thanks
Dave

 

If you have a pcmforless tune it may have too much timing on spray if you aren't pulling any. When I got my car dyno tuned my tuner ended up pulling 5 degrees of timing out and I gained alot of power, 30ft lbs of torque down low. So if you aren't pulling timing on a very agressive tune that may cause it. Other than that I would get it on a dyno to check the a/f. What jets do you have in it?

 

Check your a/f. My pcm4less is a bit lean (mean) and the nx suggested jets are lean too. So I usually just run the next bigger fuel jet for a shot.

It was probably a bit much, but I ran 35* on a 150 shot on the dyno. That was with nx suggested jets and it was nearing 14 on the a/f up top.

13-1 compression, pump gas, and no detonation.


Overly rich or lean will make the car pop through the exhaust. Also low back pressure does the same. (I get it all the time)

 

Well I always get a pop when I let off the gas after getting on it...but it's popping while accelerating throughout the RPM range...

I plugged my O2s back in (they were unplugged) and same thing happened. I purged the line a few times and it was a solid white plume every time, and the bottle was at 900psi. I've sprayed at 1250psi before without it going too lean....

I'm starting to think it's an ignition issue. I'll mess with a few more things.

Dave, I don't know the total timing, but I'm retarding 2deg on a 100 shot as per Ion Soltan (MadZ28)'s recommendations. I'll weigh the bottle later.

 

OK well I pulled all my plugs.

I'd appreciate it if you guys could take a minute or two to check out these pics.

http://img.photobucket.com/albums/v4...Cylinder1a.jpg
http://img.photobucket.com/albums/v4...Cylinder1b.jpg

http://img.photobucket.com/albums/v4...Cylinder3a.jpg
http://img.photobucket.com/albums/v4...Cylinder3b.jpg


http://img.photobucket.com/albums/v4...Cylinder5a.jpg
http://img.photobucket.com/albums/v4...Cylinder5b.jpg

http://img.photobucket.com/albums/v4...Cylinder7a.jpg
http://img.photobucket.com/albums/v4...Cylinder7b.jpg



http://img.photobucket.com/albums/v4...Cylinder2a.jpg
http://img.photobucket.com/albums/v4...Cylinder2b.jpg

http://img.photobucket.com/albums/v4...Cylinder4a.jpg
http://img.photobucket.com/albums/v4...Cylinder4b.jpg

http://img.photobucket.com/albums/v4...Cylinder6a.jpg
http://img.photobucket.com/albums/v4...Cylinder6b.jpg

http://img.photobucket.com/albums/v4...Cylinder8a.jpg
http://img.photobucket.com/albums/v4...Cylinder8b.jpg

 

They look lean to me considering they are only black on the very tip of the plug. Usually the plug if it was rich would be black lower down on the plug and the tip would not be white in color. I would pull a couple degrees, like 2 and see how it runs that way.

 

First,
How did you run these plugs. If you drove on them we will be waisting outr time trying to help you. Put a new set of plugs in the car.
Make a wide open pass and shut the car off instantly. Then pull the plugs..

If you drive on them afterwards it washes the plugs and you can not get a accurate reading.

The top base ring(where the treads are is where you will read for airfuel
The trap is where you will read the coldness of the plug / and timming
The porcelin is where you will look for detonation.

Dave

 

I drove home about 1 mile after spraying...

I'm going to try Autolite 103's now, and retard timing a few more degrees.

 

Ok,
Get a new set of plugs in there and go somewhere you can do a wot blast for about 6o foot or so. Then instantly shut off the car and pull the plugs. Take some you can put back in the car. Then get with me. I can help you from that point..
Sorry I know its not the easest way but its the right way...
Dave

 

OK I put the 103s in gapped at .035, and retarded timing 6 degrees instead of 2, and got the same ****.

Dave, I'll try to do that later or tomorrow..

 

are u still on stock fuel pump? mine was doing the same thing, put a new walbro pump in, problem went away.

 

Walbro 255....

 

If you get a chance call me.
254-420-3630.
Dave