Exhaust backfire wot

JJDAG

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ive searched a few times on here to see if anyone has this happen couldn't find anything. On my 07 gt auto bone stock no mods to engine only axle back ford racing gt500 mufflers. It runs fine driving around even when I get on it but when I floor the gas pedal and it kicks down I get a backfire through the exhaust just one bang, it doesn’t hold back, the car gets up and goes it’s just the backfire. Also never a check engine light on. Anyone hear of this or have experience repairing? I don’t want to do any damage to anything. Thanks in advance
John
 

RocketcarX

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Typically backfiring through the exhaust is fueling issue. Pull the codes and let us know what is there
 

1950StangJump$

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I know that, with headers, high flow cats, "open style" mufflers, and a tune, I get lots of popping and carrying on (i.e. the burble) -- but only as the RPMs drop once you disengage the clutch. Sounds cool, IMO. I suspect its a combination of additional fuel in the tune that goes unspent and the open exhaust that doesn't mask it.

Point here . . . are you sure yours is a true "backfire" and only on acceleration? Or are we talking about the typical decal burble? Your mufflers might exacerbate the sound.
 

JJDAG

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Yes I definatly know the difference , it’s been through state emessions and passed they would not pass it if there were codes there is no check engine light nor has there been since I purchased it . This only happens when I’m cruising along then put my foot to the floor I get 1 bang/ loud pop through the exhaust at the moment the transmission kicks down and the rpms go up fast. It runs out fine the speed goes up quite fast for a stock mustang all other sounds are normal to me like the burble bubbling on decel, that does sound nice. I don’t often floor it but on occasion I do. Also this doesn’t happen from a dead stop only when your cruising and you kick it down but only when I do that by putting the pedal to the floor not like a 3/4 pedal kick down .
Thanks for replying
John
 

redfirepearlgt

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^^^ Looks like a 3V on E85 with a N2MB WOT box and maybe a nitrous shot or some boost.
 

JJDAG

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Yes although I get mine as soon as the trans kicks down and the rpms go up I don’t think but don’t know if it shoots flames lol, I don’t have headers and I have stock cats if that matters.
Thanks for checking I really appreciate it :biggrin:
John
 

redfirepearlgt

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How many miles are on the car?

Just thinking out loud but could a partly clogged FI cause this problem? If its not atomizing the fuel and raw unburned fuel is getting in to the cats that could cause a backfire?
You flatter me sir, all NA :roflmao:

I've got a friend running E85 on a procharger setup with a N2MB box and that thing scares the crap out of everyone when he leaves the line and at every shift. Sounds like a bomb going off. I need to make a video of it going down the track sometime at night. That thing sits banging on the two step at 4800 RPM and BAM! He side steps the clutch and there is no way to be prepared enough not to climb out of your britches when he leaves the line. Its a forged setup on about 21 pounds of boost out of an F1 series.
 

JJDAG

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Its an 07 I’ve got 54k on it honestly it runs great I’ve never had an issue with it. I bought it last September with 46k I don’t floor it like this often maybe 5 times since I bought it I don’t drive like miss daisy but I do not beat on it I will never race it I don’t plan on many mods if at all I just enjoy driving it and love the exhaust note with the ford racing mufflers. I can’t get speeding tickets as my job requires a clean driving record so that limits me as well (probly for the best) this back fire is the only thing it does and it is very similar to the video but that car seemed to be a manual mine is auto and the only time is if I put my foot to the boards litterly I get that dam gas pedal drive by wire lag then it kicks the trans down the rpms go right up and it’s at that moment I get the back fire only once it does not hold the car back at all. It has passed emissions without a problem so I would think it’s running clean, it does not smoke ever that I’ve seen. And as I said before if I just kick it down but not wot it does not back fire . If I take off from a stop it does not back fire only if I’m cruising along on the highway or back road and floor it . I do really appreciate all of you trying to help me out ! Thank you all :thanks1:
 

redfirepearlgt

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The first thing would be to do as mentioned is see if there are any codes stored in memory though a CEL light is not on. Makes me think of when the guys in highschool would drive down the road, shut their car off, pump the gas several times and restart the car and generate a backfire through the exhaust. A similar effect could be happening if there is a fuel injector that is clogged and has its spray pattern messed up causing it to squirt fuel at WOT rather than atomize it which causes unburnt fuel to exit through the exhaust,hit the cat and ignite. that's all I got and it's rather weak at that. You may try running a fuel injector cleaner through the system if it is this it MAY help.

Datalogging if you had a tune and a tune device would help shed some light on things.
 

JJDAG

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I will check codes but I won’t have access to my tools for a bit. I def hear ya on the fuel I remember doing that to make people walking on the sidewalk jump. I’ve owned a ridiculous number of cars over the years most when I was younger but I lost track several years ago at 85. I’ve never noticed any of the cars I’ve owend do this at least the good running ones and most of the cars back then I drove like I stole them no mercy. I will post any findings from my code reader when I get home . Thanks again !
 

boomer9999

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I kind of miss the random backfires i used to get with my old carburetor cars with their sloppy points and loose timing chains. I actually wish my mustang would backfire a few times at least.
 

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