Hey Guys,

I bought this kit on the site a couple months ago. I had it professionally installed. I was present during the setup of the Dynotune 2 stage RPM switch and the WOT voltage was .4 and closed was something like 9.4. I took her for a test drive and WOT = no spray. Once I lifted off the throttle I immediately heard the hsssss of the shot and pulled the key while stopping. My intake tube (stock plastic) exploded and there was a small fire that toasted the dynotune switch. I also damaged the throttle body, melted a few hoses and a valve cover. The Z survived and is now back to stock but I wanted to ask the pros what could have possibly caused this issue? Thanks in advance for your help.

This is a screenshot of the equipment I purchased from the Marketplace. Please note this is not an advertisement for re-sale, I am only illustrating the items that were in the kit that gave me this issue.

 

Sounds like it was installed wrong and shot nitrous sometime other then full throttle and wouldnt stop spraying, that caused a HUGE backfire (flames) from the throttle body exploding your intake tube and catching stuff on fire.

This happened to me also just not as bad, mine backfired and blew the intake tube off the TB. The Nitrous solenoid got stuck open from debris in the line from install and caused a major backfire.

Check your install again, verify everything works with the bottle closed, listen for the solenoids opening and closing at the right time. You can do this with the engine not running with just the system armed.

Also the place that installed the swith would be buying me a new intake and paying for damages. That switch was set up wrong. GO back and Raise hell!

 

The uninstall labor, hoses, and valve cover were all free, new throttle body donated by the shop owner for $25 so I feel like they made up for the situation as best they could, especially since it was a used kit...

Unfortunately I cannot check the install since it's all off the car now. Problem is I was present and participated in the setting of the following and it still had the issue:

STEP 7. TPAS Mode
A B C = throttle position activation switch mode
0 0 2 = TPS signal

STEP 8. TPS WOT setting
Note: only applies if Step 7 is configured as 02
8.B.C = WOT voltage
While at IDLE(first try this with the key on and engine not running), press switch #2 to read and display the TPS
signal. Pop the throttle to open it all the way ñ the unit only needs to see WOT for a fraction of a second. Now
press switch #1 to save the displayed value. (You do not have to be at WOT when you press switch #1 to save)

 

They wired it wrong, plain and simple.

Also, there is a wire on the TPS sensor that works REVERSE on the offset voltage that would do exactly what you were describing.

 

Holy crap, they wired it wrong!! Most kits sprays at 5+ volts. So when you let off the gas (high voltage at idle), it sprayed.

 

God dann!!
should sue them already !!

 

Yes...definately in incorrectly wired wot switch. The voltage for the tps wire at wot should have been 4.0-5.0 volts not .4. They definately tapped the wrong wire....I don't understand why people wouldn't just tap the wire off the ecu by pin number tomake sure they're getting the right wire?

 

Ahhh the good ol nitrous backfire...


Sounds to me like you had debris in the solenoids and they were either stuck open or delayed opening or stuck closed. When you install the lines you MUST blow them out with a burst of nitrous and ensure the solenoids are completely clean, both fuel and nitrous lines. If you get any debris inside the nitrous line during install (very common when running under carpet, through firewall etc) it will hold the solenoids either open or closed.

Sounds to me like some debris held the nitrous solenoid from opening and you had nothing but straight fuel shoot in. When fuel is sprayed without nitrous at the same time it's not vaporized and just sprays like a squirt bottle (because of 60psi vs 1000psi for nitrous) so backfires are very common.

Almost 100% an install problem. Pull the solenoids, send them to zex to be cleaned I'll almost but guarantee you they have debris causing improper operation. It happened to me and to a lot of other people, this is a common mistake made by people who don't know to blow the lines clean (and make 100% sure).

 

4.1-4.9 typically.

 

There is a wire on the TPS that will do this, it was just improper checking.

 

Not to sound like an ***, but what your saying isn't really correct. Fuel alone being shot into the motor is such a small amount, it will just make the car run extremely poor under acceleration. It will never create a backfire that violent just by running fuel only into the motor, unless MAYBE there wasn't a jet in there.

I am willing to bet there is nothing wrong with the solenoids, it was just wired incorrectly.

 

Thanks for your responses guys, sorry for the confusion on the voltage but the TPS was upside down so it read 048, right side up it would have read 840 which is 4 volts.

 

It should spray anywhere from 4.1v-4.9v

On the DE the TPS wire is in the throttle body, green wire.
On the HR's the TPS wire is in the throttle body, but Nissan went with yellow this time around for the TPS.

 

Good info right there!
Thanks man

 

Yep and the green wire on the HR throttle body runs REVERSE voltage calibration, I tested all the wires before I put mine on, you can get yourself into trouble that way.

 

If you are lazy and don't want to clear your lines, just get nitrous and fuel filters, thats one thing i don't have on my setup that i plan to get.

 

considering the intake manifold/intake piping design of the HR, that makes it pretty hard to do.

 

I can see why you would say that, let me explain it a bit better.

First let me say that I was sponsored fully by NX for racing with their nitrous system. I have very intimate knowledge of setting up nitrous and racing with it. Here is a Direct port system I ran on my VW:



The red thing with the gauge is a special FPR designed to reduce 60psi OEM fuel pressure to 12psi so I can run carbureted sized jets in my nitrous system. In order to set the fuel pressure you need to do it flowing. To do that you cant set it while spraying nitrous because if you are wrong, boom. So to do so you use a Master Flo-check. Found here on NX's website: http://www.nitrousexpress.com/produc...ils.php?id=233 The reason I did this is because 200whp at 60psi with 6 nozzles is the minimum size you can run. To run a smaller shot I needed less fuel pressure. So running a FI to Carb FPR allowed me to run from 75-250hp shots through 6 nozzles.

What this does is let you setup your flowing fuel pressure as it's different than a static pressure as i found out during the test. You put a jet in that simulates the same size as my 6 fuel jets and set the fuel pressure regulator to the proper pressure while flowing. The pressure static when it wasnt flowing needed to be 15psi in order to be 12psi when flowing. Had I just set 12psi I would have been lower flowing causing my nitrous kit to run lean and blow up my motor.

The reason why I'm tell you this is the Master Flo-check uses one jet then you run a tube off it into a bucket with the car running so the fuel solenoid is open and flowing as if you were spraying nitrous. You set the FPR and run the fuel into a bucket. I turned my system to a 100hp shot (direct port 6 yes) and I will tell you 100hp worth of fuel is a lot. It sprayed out the jet at 12psi with good force and filled 1" in a standard size car wash bucket in about 30 seconds.

So lets say 5 seconds of fuel only flowing at a steady rate would be a lot of fuel going into a hot intake manifold. Even a small mount of fuel puts off a lot of fumes which can easily ignite causing a huge nitrous backfire. 2oz of fuel would be more than enough to cause a good fireball.

When a nozzle is spraying fuel and nitrous together the nitrous spraying at 1200psi is what atomizes the fuel into very small particles. So fuel spraying in at 40psi on it's own will come out like water from a tap on low. It was like how your tap flows a small stream just a bit higher than dripping where its flowing at a steady rate. That fuel just rolling into the intake manifold would be very dangerous. 75hp worth of fuel is a lot even if for just a small amount of time. If you don't believe me just un-hook your fuel line from your nitrous nozzle, put a fitting and jet so it can just run out, then open the fuel nozzle for just a second. I'll bet you spray fuel 10ft out of the engine bay. Actually don't try this, it's dangerous. Just as dangerous as it spraying into the hot intake manifold and potentially being ignited causing a nitrous backfire.

Nitrous solenoid failure is almost always from foreign material in the lines which cause the solenoids to get stuck closed or open. It happened to me with my nitrous solenoid and I ran a whole bottle of nitrous through my VR6 with no fuel. Good thing my car just idling along the return road after a run, but it was bucking and going weird. Had I gone WOT it would have blew the motor but just putting along it made it through. I get back to the pit to find my nitrous bottle totally empty.

So I'm not just pulling answers out of my *** as though I don't know what I am talking about. I have written nitrous related articles as a guest writer for HCI, Modified Magazine and PAS which were all published a few years ago.
Here is one from HCI though the wayback machine:
http://web.archive.org/web/200410200...Tech.asp?ID=12

I shot and wrote it but HCI didn't do guest articles this way back in 2002 when I did this article which is why I only got Photo Credit. I can assure you 100% that Sean didn't write this article as he didn't have anywhere near the nitrous knowledge that I do. I could post up the full article if I scanned the magazine.

Hope that helps.

 

Just to clarify for my knowledge as well, I have built probably 20+ direct port kits, and installed more "off the shelf" kits then what I can remember. I founded the first honda nitrous forum on superhonda and was even given a VCN2000 when Venom came out with that kit just for the sake of testing it and have been installing kits for 10+ years.

The problem with fuel, is that it has a round about ignition temperature of 495 degrees, so if you have intake temps that are exceeding that, there is a lot more to worry about than fuel pooling up. In 99.9% of cases when nitrous solenoids don't open, the addition of fuel only will just create extremely poor running situations, unless you had an intake design that was poor enough for the engine not to vacuum the fuel into the intake ports, than I could maybe see where you are coming from.

 

OK so since you are not a nitrous first timer, why do you not agree that nitrous backfires happen? THey happen all the time. I have seen many a honda air filter ballooned from a back fire. The ignition point of gasoline is 495deg but the flash point is the temperature at which a liquid will light its self on fire, or release vapor that can be ignited without spark. Gasoline does it at room temperature which is why it's so volatile and why empty gas tank is more dangerous than a full one.

A quick search on Honda-Tech (since you mentioned honda's) showed multiple threads right off the top of guys having backfires:

http://www.honda-tech.com/showthread.php?t=872979
http://www.honda-tech.com/showthread.php?t=227596
http://www.honda-tech.com/showthread.php?t=1380247
And finally from NX's website: http://www.nitrousexpress.com/Pages/faq.htm
I could go on but you get the point. Fuel puddling in the intake manifold can easily (and has on many occasions) ignite and cause a huge backfire. This is a well documented problem and can happen even on a kit which is not tuned properly (overly rich) or a single nozzle kit where the nozzle is placed too far back in the intake pipe. There are lots of documented cases of exactly this happening on Carbureted vehicles with plate systems as well. A quick "Google Images" for the word nitrous backfire should show you some nice full race cars with flames coming from under the hood.

Here is a great youtube video of a ZEX kit on a Cobalt with a backfire. Forward to about 0:45. He has a huge backfire and it cracks the intake manifold almost in half along with a huge flame coming under the hood. Its has a far less complex intake manifold than a VQ35 does.
YOUTUBE NITROUS BACKFIRE: http://www.youtube.com/watch?v=VYf5OIQG8XA

More on ZEX NItrous kits from the editor at Mustang Muscle:
BOOM... hahahah..

Dude, it Can, Does and will continue to happen.