The first time out this year, my car did it's fastest ET ever, but the MPH was WAY down. Everytime I would hit 3rd gear the car would act like it hit a rev limiter and nose over. I let off the nitrous everytime not wanting to risk destruction. I took the car home and found that I had pretty much fried the number 2 and 6 plugs and alot of the other plugs were looking pretty rough with pits in the electrodes. After a swap over to a new set of NGK Tr6's, ohming out all my plug wires, and cleaning up the cap and rotor I took the car back to a 1/4 mile track only to find it had the same issue again! I'm not sure what could be causing this. I know my fuel pressure is holding (gauge mounted under the hood) the only thing I can think of is either A the coil, or B the fuel filter. Any ideas on what could be causing this? Oh I almost forgot to mention I changed over to an X piped exhaust, and installed the large down firing NX solenoids in place of my old NOS solenoids. Jetting is .073 on the nitrous side, and should be rich on the fuel side.

 

When you say the fuel pressure gauge is under the hood, do you mean in the cowl area so that you can view it when going down the track, or when you pop the hood, you can verify your fuel pressure at idle?

Did you pull any timing out?

To me it sounds like your running out of fuel, going lean, and causing it to eat the plugs.

 

Fuel pressure gauge is under the hood, it's set up to be viewed from the cowl on a long length of AN line but I haven't made a mount for the stock hood to keep it in view. It's holding it's normal pressure but it could be losing volume when demand goes up. I pulled out 6 degrees of timing starting at 2500rpm via the Digicon, it runs right up in 1st and 2nd so I'm pretty sure that's ok. I need to recheck the plugs after the next run and maybe pull 2 more degrees of timing, see how it reacts to that. I want to do all of these things to diagnose it but I really don't want to be blasting the car over and over again on nitrous; it gets so expensive

 

Ya verify the fuel pressure in third. I used to have MAJOR fuel issues being just N/A but i would lose pressure in first, and never recover.

Have you tried cruising up to 3rd gear, then going WOT, and spraying?

 

That's what I'm going to try this weekend, I'll probably duct tape the gauge to the windshield ghetto style LOL. I'll swap the fuel filter first and see if it's full of crud (highly possible since I've ran all kinds of fuel concoction through the thing) then swap out the coil, then take her for a run. If that doesn't do it I'm going to pull 2 more degrees of timing, and if that doesn't do it I'm going to lose my mind

 

colder plugs, smaller gap, after market ignition???

Raf

 

What is your fuel side jetting and what is your fuel pressure? What kind of fuel pump?

 

MSD 6 A running fresh TR6 plug with .035 gap, ACCEL 300+ wires that all ohm out good, Walboro 255lph pump doing 45 idle, 50 on throttle, .041 fuel jet on the fuel side. This setup when the car was about 200 pounds heavier went 12.2 twice in a row with no issues, I changed the solenoids, put on the K member, pinto rack,etc, installed true dual 2.5s with an X pipe all mandrel bends, bypassed the heater and now I have these issues. It had to be something that happened while it was sitting or being cruised to town and back the few times I've driven it.

 

Update: I changed ran the car with the ignition stuff changed out and new plugs, same problem. I then redid the a new prom, lowered the nitrous jet to .070 and upped the fuel jet to .043, I ran the car and yet again it fell on its face in 3rd and felt funny in the middle of 2nd. The latest idea I've had is that it's possible my proms were cutting out PE mode fueling at full throttle because the $6e based proms are built to shut off PE at anything over 4.8 volts on the TPS (mine runs over 5 WOT). I'm really hoping this is it, I'm going to swap this out, pull the plate and make sure it's not obstructed, and change my plugs yet again. On the bright side, through swapping out my ECM I managed to cure my idle fluctuation, the car now sits at a dead steady 650 rpm and never hunts or surges!

 

IT WORKED... well kind of, I ended up with some crazy issues on the way to the track that turned out to be my Digicon timing computer dying on me. It would throw a code 42 so I had to bypass it and was stuck running 36 degrees timing all night. I went to Bean Blossom drag way threw in a .057 and a .035 jet and decided it was go or blow. With 20psi in the ET Streets the car went 8.000 at 88mph. and held strong all the way through third. I was really excited because I had won the same event I went to on an 8.0 index so it was going to work out well but the night got rained out and I had one heck of a scary ride home. Someone should throw up a warning to nitrous users about the TPS going over 4.8 volts, this was really screwing up my engine and my times!