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07-09-2011, 10:50 AM | #1 |
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N54 Backfiring?
Replaced stock midpipes with (previously owned) CP-e catless midpipes. The Downpipes & muffler are stock.
I love the tone, but I get a lot of backfiring now. I didn't think removing 2 of 4 cats and the resonator would cause this. Anyone else see this before? |
07-09-2011, 02:41 PM | #2 |
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are you sure its backfiring and not just the "gurgling and popping"? I have full catless and I get lots of gurgling and popping but they only time i ever get a hint of backfire is when i am wot at low rpm and then shift gears before 3500 or so
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07-11-2011, 08:29 AM | #3 |
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[QUOTE=330iSB;9988993][QUOTE=evilstib;9987893]Replaced stock midpipes with (previously owned) CP-e catless midpipes. The Downpipes
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07-11-2011, 08:51 AM | #4 | |
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Heck! My N54 exhaust is all stock and it also gurgling and pops! I love it though. I think plenty of V-Max runs on the Autobahn helped in reaming out my exhaust pipes. lol I know lots of people are surprised when I tell them my exhaust is all stock! OP - I bet you re-used your old exhaust gaskets. Most backfiring or severe popping comes from an exhaust leak upstream. A true back fire would mean your engine is running super lean. I bet its your old (leaking) exhaust gaskets. Have a helper take some rags and hold them against the exhaust tips while the engine is running. Then YOU can go under the car (while its jacked up and on jack stands!!) and check for leaks. I bets its those exhaust gaskets at the downpipe/main cats to mid pipe flange. They take an awlfull amount of heat and are prone to be "one time" gaskets. It could also be further back at the muffler too. Good Luck, Dackel |
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07-11-2011, 01:21 PM | #5 | |
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To get REAL backfire (flames out the exhaust tips), you'd need to be completely catless.
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07-11-2011, 07:10 PM | #7 | ||
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07-11-2011, 07:15 PM | #8 |
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It's unburned fuel detonating in the exhaust because the exhaust is so hot it causes it to ignite. They're not massive explosions because only a little unburned fuel gets there.
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07-11-2011, 07:16 PM | #9 |
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That is a myth - I believe. I have had some tuning experience with SW tuning (on Volkswagens and Porsche's)many years back, in the early 1990's. Most of the time a popping back fire is from running too lean a fuel mixture. I know common sense says its must be too rich of a mixture... but it is more common for it to be from a lean mixture. Dackel |
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07-11-2011, 07:19 PM | #10 |
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I apologize for the third post, but I can't modify a previous one from my phone. Dackel can be right about the gasket though, it's worth looking at. Also, I hope you have some sort of aftermarket tune with that downpipe otherwise I bet you that's your problem right there and you'd better fix that situation ASAP.
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07-11-2011, 07:21 PM | #11 | |
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07-11-2011, 07:25 PM | #12 |
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No myth, Dackel. It has it's benefits, but the downsides are clearly minimally worse gas mileage and your not making as much power as you can that way. Although I would argue reliability over peak HP any day. Too many factors that go into ECU tuning for this topic right now.
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07-11-2011, 07:25 PM | #13 |
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You guys are all wrong. It can't be a backfire because backfires come back through the intake manifold.
It may be an afterfire though... :nerd: OP you're probably confusing the burble and gurgle with an afterfire |
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07-11-2011, 07:30 PM | #14 |
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Ok, you win by default. Myself and many others have all called it that forever. I guess it's like breaking a bad speech habit. Lol
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07-11-2011, 08:49 PM | #15 | |
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HPF intercooler coming soon! Woooo hoooo |
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07-11-2011, 08:55 PM | #16 |
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Hi. If you call it gurgle then in confused. It's louder than my straightpipe exhaust civic ever was, happens in first gear (auto tranny) when shifting into 2nd. I'll go take a startup vid and post.
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07-11-2011, 09:15 PM | #17 |
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k, so don't get me wrong, I downshift just to hear the burble/gurgle...love it!
First gear, WOT, when it shifts to 2nd it's not a gorgeous sound...big pop/bang noise. Here's a startup video, I'll ask the GF to help out with a WOT run in 1st tomorrow. Anyone else notice my exhaust starts to glow blue? lol! |
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07-12-2011, 06:15 AM | #19 | ||
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07-12-2011, 08:01 PM | #20 | |
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If it's a true lean backfire, and it's only on decel, then no big deal (BMW probably just got agressive and turned off the fuel injectors completely on decel), but if it's a lean backfire at WOT, then that would be bad.
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07-13-2011, 07:36 AM | #21 |
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02-04-2013, 03:20 PM | #22 |
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this is normal when removing cats and happens with my 6MT all the time, i love it. op isnt talking about the "gurgle" its an actual POP. heres a video. (this particular car is FBO, RB turbos and meth but i produce the same sound FBO, stock turbos and no meth)
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Last edited by AndrewC1989; 02-04-2013 at 03:38 PM.. |
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