4.6L (1996-2004 Modular) Mustang Technical discussions on 1996-2004 4.6 Liter Modular Motors (2V and 4V) within.

backfire, bad gas or crap tune?

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Old Aug 12, 2011 | 02:49 PM
  #1  
zero2005's Avatar
zero2005
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Default backfire, bad gas or crap tune?

so i had a tune burned just so i could get my car running (diablo chip) so i could attempt to drive it to the dyno to have it properly tuned. guy did it for free. not really sure on the specs, as i shipped it to him and he shipped it back, i just provided him with all the info and he burned me a "safe" tune.

but now i'm getting some backfiring? it started after bleeding the brakes, i had it running for about 10 minutes before that at idle and it ran perfectly fine. i dont know if maybe that when i jacked the car up it shifted the gas around and caused nasty crap to mix in or what.

running green top 42'lb injectors + matching MAF (PMAS), 9.55 CR short block (MMR), stage 2 turbo cams (MHS), and an on3 turbo kit.

now, the car has been sitting, with the same gas since last thanksgiving, 93 octane, and i put a bottle of injector cleaner (think it was STP) when i first "put it to bed". then again march of this year, and again this past week.

now im contemplating, either its something with the gas, something with the tune, or something way way worse.

i do plan on doing a standalone computer (megasquirt) or maybe the Delta Force Commando at some point, so i'd rather not waste any money on another tune, as well as going with a complete return style, sumped fuel tank setup.

i've considered throwing the stock injectors, stock tune, and stock maf back in to see if it runs better that way?

oh, and for some reason when i bled the brakes, i did it like AM.com says to - farthest first to the closest, and the brakes are REALLY squishy(and it looked like they were not compressing at all). i replaced the front brake lines with stainless steel JM lines (american muscle), and i had to replace the front driver side caliper because the bleeder snapped and was impossible to remove. is it possible i have to "prime" the master cylinder?
Old Aug 12, 2011 | 05:23 PM
  #2  
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Romer
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Joe at tricktuners have been tuning my car. One of the first drivable tunes I got had a lot of backfire in it. everytime I changed gears it was popping. He claimed the software had randomly changed some tables. Anyway once he corrected it the backfire was completely gone. anyway what I am saying is that it could very well be in the tune.
Old Aug 12, 2011 | 06:30 PM
  #3  
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mrtstang
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Similar thing happened to me after i got a custom dyno tune. The car runs much better, but rumbles/burbles much more on decel.
Old Aug 12, 2011 | 08:11 PM
  #4  
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FlamingoGT
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Out of curiousity, why did you put 3 bottles of fuel injector cleaner in the same tank of gas? I'm sure that didn't help anything. And bleeding your brakes wouldn't have anything to do with the way the engine is running.
Old Aug 13, 2011 | 10:28 AM
  #5  
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zero2005
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i couldnt remember if i did or not, so i just threw some in there. probably should have been more clear sorry.

i'll probably drain the tank anyways at this point, as i think i'll just have the tank sumped and go with a return system. and i think i'll start ordering parts for a megasquirt.

and i'm saying that maybe because when i bled the brakes i had to jack the car up, and it could have caused the fuel to slosh around any crud that might be built up in there.
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