U Can't Z Me

Ok, so I finally installed my new TNT kit last week and went to test it today.

It pulled awesome through 1st gear, then in 2nd it "coughed" 3 times and I got out of it. By cough I mean it made a hacking sound and the car jerked a little when it did it.

It didn't go lean. It didn't have excessive knock retard, and it didn't sound like any kind of detonation that I have ever heard.

What could it be?

If you have any ideas let me know.

Thanks,
Eric

Edit: I was on my way to work when I originally posted and foregot to add that the "cough" was accompanied by a little black smoke out the exhaust, and also there was a little bit of nitrous surge (like people get with the FPSS) that was seperate from the "cough"

Fuels94TA

Did you have good bottle pressure? Also you should always should check your system out before you use it on the car by testing it out and listening for the solenoids to click on and off.

Vinny

U Can't Z Me

Just so you know, I'm not a nitrous newbie, I just upgraded from my old Compucar kit to a TNT kit.

Yes, bottle pressure was right on, 1000-1100. I checked the whole system and everything worked properly (solenoids clicked, no leaks).

There aren't any kinks in the hoses, and I am NOT running a FPSS.

Any ideas why the car would have done this? I made a few quick runs from 60-80 on my way to where I made my test run and it was fine. It just started to do it when I made the full run and after it was in 2nd gear.

Fuels94TA

Maybe check out the WOT. On my NX system my wot switch would move around and wiggle loose from the TB and give me a intermediate passes. I can't think of anything else beside a clogged filter.

Vinny

U Can't Z Me

Well it's a brand new kit so the filter should be fine.

And I am not running a WOT switch, it's on a push button.

Maybe a misfire? I am running NGK TR6 plugs, but they are about a year old.

Z28ROC

I was also thinking plugs. How big of a shot are we talking about?
What kind of ignition are you running? Maybe some autolite 103s would be the ticket. I like the autolites much better than tr6s.

U Can't Z Me

I am running a 100 shot. My ignition is a MSD 6AL and a MSD Blaster Coil. I am running MSD 8.5mm wires.

The car ran fine with the TR6s with the old nitrous set-up, so I don't think I need a different type of plug, maybe just new ones.

I might try to change those anyway.

Someone suggested that I may be running really rich, which would cause the black smoke. My O2 readings were in the 960-970s, but is that rich enough to cause this?

The car runs great off the nitrous. I really want to figure this out so I can get some good runs in.

TCAL95Z

What jets are you running and what was your AF ratio?
I'm using the same kit and I was very rich on the dyno.
Lower than 10
That was with the 100 and 150 jets

U Can't Z Me

I was using a 100 shot. Not sure of A/F ratio, I was just going off the O2 readings on the scanmaster.


Ok, I tried a 75 shot last night instead of the 100 and there were no problems!

BUT: It didn't seem like there was much of an increase. All this leads me to beleive that the kit is jetted very rich.

Anyone have any way to correct this problem with the TNT kit?

Maybe use 75 fuel jets and 100 nitrous jets???

TCAL95Z, any suggestions?

TCAL95Z

That sounds like you have the same problem as me.
My car never coughed but it was running so rich that you could see where the car was speeding up and slowing down on the dyno graph and with the 150 jets I only gained 15rwhp.
When I called TNT they didn't have much to say except to try the 75 shot fuel jet because that is their smallest fuel jet.

I plan on seeing if I can get a 125 shot Nitrous jet and then putting in the 75 shot fuel jet and playing with the nitrous jets until I get a good combination.
I had a great baseline tune so I know it had nothing to do with the way my car was allready running. I think it's a problem with these kits. I'm hoping some more people will respond.

I think you should get your car on the dyno to tune it incase you go too lean

MorePower4me

Huh, that's pretty weird. When I first installed my kit, it did the same thing. In my case it was 2 things. The first, i had no heater, unfortunately it doesn't look like that is the problem for you. The second thing...I noticed that the TNT kit seems to be incredibly sensitive to N20 line positioning. I had a couple of very small, gradual bends, and it did the EXACT same thing. In my case it ended up being a large radius 90* bend I had put in, and also where i ran the line through my T-top well the line was kind of squashed. It was putting the whole amount of fuel through, but very little N20. I was really thrown for a loop as to what the problem was, because I did not see any kinks, but it was just a very small one hidden out of the way. Hope this helps...


Tom, I am happy to see you finally got the TNT kit. Once you get the kinks worked out I know you will love it.

-Brian

TCAL95Z

Hey Brian,

Thanks for the tip. I did have a kink in my line but I thought I had it out. Sounds like I better check all of them again.

Good to hear from you.

Thanks
Tom