nitrous backfire???

[daracboy82]

So I sprayed my car for the first time last night with a 150 shot wet kit from Nx. Used the wot switch. As soon as i sprayed it pulled good for a second then popped. As soon as I heard the POP I let off a killed the nitrous. The car is running like shit as it sounds like it has a horrible miss. I talked to a buddy and he said I may have burned or fouled a plug. Went and got some ngk tr6 plugs and put in it with no luck. Didn't change anything. Same guy said to start it then unplug the mass air flow meter to see if it died or changed anything. Did that and nothing changed whether it was unplugged or plugged. Another guy told me that I may have burnt a valve???? I'm gonna go buy another mass air meter this evening and try that tomorrow but any other input would be greatly appreciated. Also, I have a nitrous tune on my sct tuner and it was set to that tune when I sprayed it....

 

[forcefedhatch]

Possible burnt or bent valve, happens I've done it, try the maf after that I'd try stupid plumbing stuff, check fuel pressure etc, if no dice prepare to tear it down you may have a bent/burnt valve


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[twovalveterror]

I'm just beginning to learn about nitrous. but a backfire will usually call the intake into question. have you made sure you don't have any fine cracks or the like on the manifold? if you were spraying from a low rpm, then some of the nitrous could have pooled in the intake until air started flowing. causing the backfire. for this reason, when I get my kit, I'll be using a window switch in conjunction with the WOT. it allows the nitrous to kick in at a pre-determined rpm at WOT so it doesn't have a chance to pool.

 

[Musturd]

Window switch is one of the best forms of insurance when playing with nitrous

 

[jo4roush99]

Were the plugs you pulled out in good shape? If none of them are burnt or melted, I doubt you did anything major. Usually the plug burns / melts before anything major is damaged.

 

[quickstang_1994]

you drive a 4.6 or 5.0?

 

[twovalveterror]

probably a 4.6 seeing as he has an SCT tuner.

 

[Mrstangerbanger]

S

sounds like headgasket to me .... Do a compression check that will tell you
does it smoke when you start it ?
Open the radiator cap and rev the car if you see bubbles its head gasket

 

[Musturd]

Yea very well could have popped the head gasket I know 5.0 guys do it lots

 

[forcefedhatch]

I have destroyed many head gaskets..


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[daracboy82]

4.6. I got a compression tester today. Gonna check that tomorrow. No smoke while its running. Just idles like it has a massive cam....

 

[daracboy82]

Plugs didn't really look too bad. Some scorching but not awful....

 

[quickstang_1994]

sounds like the intake (very common)spray some carb cleaner on the intake and see if it changes the idle

 

[Mrstangerbanger]

sounds like the intake (very common)spray some carb cleaner on the intake and see if it changes the idle

Could be but then again my car ran perfect with a bad headgasket so you never know ...

 

[RichV]

Nitrous backfires usualy damage MAF meters and blow off vacum lines. Sounds like you may have a bit of both.

Do you have a return or a returnless fuel system?

 

[Leehamrick]

I'm going to throw in my .02
If you have a dead miss shouldn't you figure out which cylinder is causing the problem and concentrate on
that cylinders/cylinders? I would think that would be quicker and more cost effective
If the bad cylinder is not firing at an idle it should be easy to find
If nothing else fire it up cold let it run for 30 seconds and feel the headers and see which is cold or hot.
Or kill the cylinders one at a time while it's running.

If it backfired through the intake and that's what caused the miss I bet you blew off a vacuum hose or intake gasket some kind.
I have seen a lot of bent and burnt valves but never from a back fire.
Let us know what you find.

 

[quickstang_1994]

Could be but then again my car ran perfect with a bad headgasket so you never know ...

yep, but i knew your was a bad headgasket as soon as you told us about it, i have had the same problem with mine alot.

 

[96TANGERINEGT]

I seen a friend have a nitrous backfire one time blew the air box apart , and made a awesome blue flame looked cool as hell at his expenses lol haha

 

[miss2slocoupe]

i dont know a whole lot on this subject either. I heard its always good to tune a car on this, could this be a problem with it? or be helping the problem?

 

[RichV]

Nitrous can backfire with or without tune. The trick is getting the mix right. With a wet setup like the OP has, he is spraying fuel and nitrous at the same time. A dry kit only sprays nitrous and depends on the injectors to add the necessary fuel.

On the wet setup, I read up a lot on them when I switched a 86 Saleen from a dry to wet. I know that fuel pooling was the issue with backfire. If the fuel sprays before the nitrous, or you have too much fuel, when nitrous gas comes in contact with it, it makes it a very volatile mix. When it ignites in this state you get the cool blue flame, and a very powerful explosion. On the wet setup, it is important to purge the lines so the nitrous is right there when you spray, not 5+ seconds away. As are the pills you put in the spray nozzle, you must size them according to the manufacturer charts, but typicaly anything in the 125+HP range you should put it on the dyno and watch a/f, and increase/decrease the fuel pill if necessary.

I was watching at the line one time a Mustang lauched on the spray and it backfired. I watched the upper intake and his hood go about 15 feet in the air.