Missing Badly On Spray

i just got back from the track and spayed it for the first time.it didnt go so well,it was breaking up badly.its a 100 dry shot on a stock lt1 with 120k on it.timing is at 36 deg,and motor was on pump gas.it kind of felt like it was hitting a rev limiter,or more like it was about to blow up!the miss was instant as soon as i went to full throttle(spray is on a micro switch,on at wot). i was at a little over 3000 rpm,but when the juice kicked on it started to back fire and i could tell it was not happy, so i coasted the rest of the way down the track.the car runs great off the juice.few mods like cai listed in sig.i know to check the fuel pressure first, and then i guess i should replace the cap,rotor,plugs and wires.its just that my new motor is close to being done and its a non vented opti,and anything i buy for the dist. will only be used for a month or so, so id rather not wast any money there.i wouldnt mind putting plug wires and plugs in it,but that might not help.thanks guys!
dan

Mine did that at 50 shot, it made all the difference in the world goin to colder plugs, completely went away. I know what you mean when it was missing bad. Make sure you have colder plugs, every 50 hp 2 degrees retard timing and dyno your car with A/F. Start off with a smaller shot get your car tuned and make smaller adjustments as you go higher in the jets play it safe. Like i said mine missed bad at 50 shot if i wouldve started at 150 i wouldve most likely blown it. There are bunch of other stuff you can do to be even more safe but that should do you fine.

do you have colder plugs? How are your injectors doing? What gap do you have on the plugs in there? How was your bottle pressure and did you have enough nitrous in the bottle? Lot of things to check here.

I recently went to the track and sprayed the car. On the fifth run it started breaking up just like you mentioned. My issue was that the bottle was getting low and the engine was getting doused with extra fuel (wet kit). Pressure was still good but must not have been picking up a solid supply of nitrous.

-Brian

thanks alot ,im going to start with the plugs and checking the fuel pressure.how do i check the condition of the fuel injectors? and also what plugs do you recomend?ive heard that the stock platnums dont like the nitrous.

Do not use platinum at all, fuel injectors can be checked i forgot how but my mechanic did it for me, no i just check for my fuel pressure at my regulator. I use TR6 plugs but there are different ones you can use as well that work just as well if not better. Those two things are a good start, again start off at a low shot and work your way up. Make sure A/F and timing is good.

just wanted to remind everyone to check there plugs before spraying, mine were the stock ones with 120k on them! oops!!!,gap was .065!,the only reason it didnt blow itself up was because the spay was putting the fire out,haha.thanks again.

Don't use platinum plugs, you want to use a copper conductor plug when using nitrous. For the shot you have, a one step colder plug is a good idea.

When you check the plugs, check what gap they were out. I believe you want a .035 gap as opposed to the factory .050 correct me if I'm wrong. It's been a little while since I changed my plugs. Also as already mentioned, make sure you go with a copper plug and not platinum.

-Brian

I would say .035 is the max gap for a 150 shot. Never spray a 150 on stock plugs.

it looks like there is a little point comming out the electrode,was this were the platinum used to be?they only say ac 906 on them how do i tell the heat range and thread size without the first numbers?i know its a 14mm,but the heat range number isnt there.did they all come with 41-906 from the factory?. ive been trying to cross referance them to a standart plug one step colder, but im having trouble.i learned to look up my part numbers before walking into the parts store.

swap in some TR6s if you have the time, like someone else said they're a world of difference.

ok thanks alot, tr6 it is!

ngk TR6 plugs gapped at 35

also what injectors and ignition are you running....the LT1 dry kits bump fuel pressure and your injectors may not like the higher pressure.

Is too much fuel (9.8:1 AFR) a reason for this problem? I just ran my 100 shot this last week and am having the exact same problem. The car runs great off the line and just will not rev past 5800 RPM on the spray. Car back fires badly through the exhaust.

My fueling was way inconsistant as it dropped lower and lower into the run. I am running speed density and found out that I am spraying right onto the IAT sensor so it dumps more and more fuel the further the temp drops. The IAT droped from 50 deg C down to -6 deg C. The injectors are adding an extra 20% fuel into the motor on top of wet shot. I would like to think once I solve this problem that it will run fine, but I have my doubts.

I am running ngk TR6 plugs gapped at 35 with E85. Also the nozzle is where the mass air used to be. (Is that too far away?)

i have the same problem also n/x wet kit 100 hit ,but mine is intermitant some times it will hit hard others it wont i got tr6 gapped at 32 thou so im a little interested in this. i was thinkin the fuel pressure switch was actin up but im usin the nitrous as my bottle is gettin lighter every time i hit it "yes on a scale for measure".if i shut the nitrous off when it acts up while still w.o.t"i have it on a switch" it still misses and acts up till i let it idle down then it acts ok like i said its intermitant im wonderin if im gettin to much fuel and its loadin up .bottle pressure stays at 1000 psi .my fuel pressure test port is now my fuel feed for the fuel solenoid .needless to say im at a loss

A 9.8 AFR is way fat and will kill the rings. I beleave what ever afr makes max power on the motor is what you want to shot for on nitrous. It is best to look at the plugs.

If the afr is decent and it is still breaking up it could be bad wires or a weak coil.

Something weird on my rx7 that has never happened on any of my nitrous setups before is the car will break up if the motor is cold(below 170 degrees), but above that it runs fine. Weirdest thing I've seen, but I just get the motor up to around 185-190 degrees now and no problems.

I believe that in the instuctions that came with my kit it says to make sure the motor is up to temp before spraying. I don't think that's the OPs problem, just thought I'd throw that info out there.