So last week was my first time ever having an issue with nitrous. I have a 100wet shot on my 2001 C5 and been using it for almost two years. I wanted a little burst of speed so I arm my window switch and I start in 1st gear at about 30mph. I floor it and BOOM, I see sparks and the car shuts off. I pull over and open my hood and flames are shooting from the air box, which I pull out and put out the remaining flames with a bottle of vitamin water and towels I had in the trunk.

After putting out the fire I try to start the car, after a few hard turns from the starter it starts but with pretty loud tapping comming from the top end (valves) of the motor. So I drove the car about 15miles to the shop, only to notice that the engine seem to be spitting a little oil out of the throtle body. After running some test they said the top part of the engine isn't getting oil thus the tapping. The short block has oil pressure and top end does not, which according to the shop could come from a blown head gasket or a cracked piston.

What does that sound like to you???

 

Not good, and one of the reasons I don't like the wet hits on the Vettes, as they seem more prone to backfires compared to other makes. However, just be glad that you didn't dislodge your fuel rails which would have been so much worse. Anyway, you diagnostics, running a cylinder leak down test will pin point exactly what your issue is. Trying to guess the problem out, will usually be just that, an educated guess. Likely you have broke a ring land, a ring it self, a piece of something has got into a valve seat. If it's spitting oil into the intake manifold you probably have compromised your ring seal and the pressures from normal running (blow-by) is coming up past your rings and carrying extra oil, and due to reversion it gets into the intake. The oil pressure on bottom end and not on top end makes absolutely no sense to me what so ever, and never heard of a motor doing that, but hey I don't claim to know everything, lol. I had a high rpm lean backfire due to my own fault running with out a WS, but anyway, because it was a dry hit and no gas or gas fumes in the intake tract it just blew a hole in my stock intake, anymore violent and I would have had a fire due to the rails being dislodged. Now I am running a burst spacer on my new intake. I sure hope your problem is simple and you get back running soon. But, if the motor needs help, well then it's an opportunity to forge it, or maybe throw a inexpensive 408 in there. That's what I did when I blew my stock ls6, and am broke, but happy as hell. Keep us updated, as I would love to follow along and am sure many others would also.

Edit: Oh yea, make sure you find the issue that caused the back fire. You may have gone lean. Lean is the #1 reason for back fires under way or at higher RPMs. Could be as simple as a clogged fuel filter or at least partially, which can happen over a period of time. We all need to keep on top of the fuel filter issue.

 

so does that mean new motor??? Lord I hope not, as that wouldn't be in my financial plans right now. BTW I think it did run lean because I left my bottle warmer on too long, the pressure was at about 1400, which I realized after the back fire.

 

The only way to know for sure is to run a cylinder leakage test. This testing procedure can pin point whether it's an intake valve, exhaust valve, rings, head gasket and so on. You can do the test your self if you can get the equipment, maybe rent it from a shop and that will save some $$. I hope it's nothing serious? Sometimes we luck out and no real damage done. Have you pulled the plugs to see if they show any damage, like missing electrodes or some splattered aluminum stuck to the plug, and/or heat issue. If you have a pic and post it we might be able to determine a lean issue.
Robert

 

The shop has my car, ima prob go there on Monday to see if I can have the leak down test done, thanks for the info

 

How is it the vette is more proned??? LOL same intake same motor. LOL

Maybe vette guys just don't do there homework(or there on mechanical work for that part) and get it wrong. LOL

 

Yes, please elaborate on why a vette would be any different from any other LS-based car?

Thanks!
99 FRC

 

Pull the heads & see.

 

Not really sure in an absolute way. But the Vettes launch totally different than other cars (IRS). They seem to want to bog a bit and this can lead to problems. Also, I have noticed that the Vettes, and Z06 especially, comes with a tune that's really not optimum for the wet hits, esp if we haven't looked at the a/f ratio. Often we see 11.x:1 from the get go (and seen as bad as 10.x:1) and this is the factory PE multiplier, now with that added richness and bad launching, or any kind of glitch, and it seems the Vettes can become fire bombs. Has no one else noticed that the Vettes percentage wise seem to have more intake back fires? Or is it just me because I am more into the Vette seen? So bottom line, like Shiznity said, the Vette guys are probably not on top of things, where as, they should be even more so than other makes. Now this is just speculation at this point, so...
Robert

 

Didn't you guys see the C6 Vette video that was posted in the last couple days, a back fire and burn down video. Check it out, can't be to far away.
Robert

Edit: Here it is, what a coincidence two threads on this just days apart, but found the video.
http://www.youtube.com/watch?v=-1cPu...eature=related

 

The issue is all the extra fuel not the wet hit. and the lack of a window switch. on a manual that may bog guys should be bumping the window up to make sure it kills the spray before it gets to low of an rpm.

THe extra fuel that don;t burn off can pop off with the intake valve open and cause the back fire. To many guys run way to rich!!!

 

Isn't that true, being overly rich can be just as bad as being overly lean.
Robert