I am having problems with my dry zex kit on my tpi.

The problem happens at different rpms. It feels like the nitrous shuts off or the motor has a dead spot and then regains rpm and goes again.

I did a couple of runs at the track and the nitrous only stays on in 1st gear then the vac line off of the afpr keeps falling off. We tied it to stay on then now the nitrous is turns on and off intermittingly

Though it was the full throttle switch, checked it with a scanner and it still read over 4 volts, not the answer!

The fuel pressure stays up the whole time. The activation switch is working. The bottle pressure was at 900-1000psi.
I was using about 92-93 octane fuel.

Anybody have this problem?

Could it be I need a better ignition?
Could it be a vac line is leaking?

Any help would be great!
I got another race on saturday and need to get it going!

 

Vac line is leaking and causing a drop in fuel pressure therefore shutting off the n2o.

What was your fuel pressure at when you were spraying. A dry shot should be really high.

 

How big of a shot are you running? Just a thought here... could the computer be pulling timing out due to pinging?

 

Maybe it was leaking, but the fuel pressure did not drop.
I have a short sweep fuel pressure gauge on the a-pillar and when I checked it, it was over 75psi and never dropped even tho I had loss in power.

I am running 75hp dry shot.
I had the scanner on the car while the run was going and it only pulled timing off the line to about to 2000rpm. After that, it doesn't pull anymore timing out
The problem happens about 3000rpm, I think, the run happens fast.

With that, any more help?

 

How old is the kit? Only problem I've ran into personally was a bad N2O solenoid from a brand new kit. The car would take off and then really slow down due to all the fuel dumping in. It wouldn't pick back up again unless I'd let off the button then press it again. After changing the solenoid, whoa baby

 

check the n2o filter . i don't know the location
on a zex kit but they are usually on the inlet to the solenoid .
they get clogged a lot of times and you will
have a shot of n2o but it cannot flow enough
to keep a steady supply going .

 

I gotta try that, that might be it! Sounds just like it.

I don't have a filter, should I ??

 

you have a fuel filter b/c you don't want crap going into you engine, so YES, you should have a n2o filter.

I ran one for a year w/ no problems, and no A LOT of others who don't run them, but those are the same people that heat their bottles w/ a torch.

 

Well, we might have found the problem.

First problem was my launch. I was engaging the nitrous too early(off idle). I have now tried the launch by punching it to 3/4 throttle till about 2000rpm and 100% throttle and nitrous comes on.
What I think the problem was too much fuel and the car just starts to puke and run like crap. Off the idle ran good, for a while, b/c it the motor was still able to burn the fuel(dumped in by the afpr) but then as the rpm goes up, too much fuel.


2nd problem is the coil. We tried another coil and it didn't puke. Tried both coils off the idle and the car runs like crap. Launch @2000rpm and the car(with the 2nd coil) runs better(no puking).

Hope that does the trick.
I am going out tomorrow to do more tuning then racing on saturday so I will post results.

 

My kit is a dry kit. So I DO have a fuel filter on the car but NO nitrous filter(unless it is in the "management" system in the Zex kit)

 

I know you have a fuel filter, but you should have a n2o filter as well.

And NEVER spray off idle. That's a good way to blow a head gasket. The cylinder pressure is a lot greater at low rpm then at 3000+. Don't spray under 2500rpm.

 

There should be a screen (nitrous filter) somewhere in the system. Wether they have it hidden away or what, it should be before the solenoid.