5.0L (1979-1995) Mustang Technical discussions on 5.0 Liter Mustangs within. This does not include the 5.0 from the 2011 Mustang GT. That information is in the 2005-1011 section.

Backfire on hard accel at 4000 rpm

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Old 07-16-2006, 01:26 AM
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Erik90LX5.0
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Default Backfire on hard accel at 4000 rpm

Just wondring if anyone ahs run into this issue .Car is 90 lx 5.0 stock heads and cam off road h pipe magnaflow cat backs . CAI 70mm tb and trickflow street heat intake timing is at 10 btdc . AOD w/3.08 gears .It is load and rpm effected if engine load is low and rpm is at 4000 will not pop thru intake .Does not feel like it is starving for fuel idles great and cruise great just when you mash throttle to the floor and it gets to around 4000 to 4500 it will pop thru intake.also has stock injectors thanks
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Old 07-16-2006, 02:05 AM
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Synyster Racing
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Default RE: Backfire on hard accel at 4000 rpm

Well I had a similar problem a few years back with another Stang I had, It turned out to be a blown head gasket. Don't ask why or how it was determined, but the guy was right. It only happened at a high RPM. When I took the head off the gasket was blown between the 6th and 7th Cyl... This doesn't meen this is your problem, but it's something else to think about. Synyster
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Old 07-16-2006, 02:13 AM
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Erik90LX5.0
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Default RE: Backfire on hard accel at 4000 rpm

Thanks for the info and yes I agree your car looks better in the white lx trim
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Old 07-16-2006, 02:14 AM
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Synyster Racing
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Default RE: Backfire on hard accel at 4000 rpm

Thanks man
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Old 07-16-2006, 02:20 AM
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will
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Default RE: Backfire on hard accel at 4000 rpm

Sounds like you need to bump timing up to 12 or 14 deg
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Old 07-16-2006, 04:33 AM
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Tims 88GT
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Default RE: Backfire on hard accel at 4000 rpm

is your cap and rotor any good? might have a crack, mine did something like that.
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Old 07-16-2006, 03:15 PM
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Erik90LX5.0
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Default RE: Backfire on hard accel at 4000 rpm

I am goimg to try and upgrade the ignition first and retest it.I did notice it with the stock intake , the backfire seems louder since I upgrade to the Trick flow intake . Thanks for the reply
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Old 07-20-2006, 02:38 AM
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Default RE: Backfire on hard accel at 4000 rpm

Installed MSD blaster coil and Dist ca and rotor ,cked dist shaft for wear cks good. Any new ideas I am all ears .This is my first Mustang and I really like the car just cant run at the track till I get this issue fixed Thanks[&:]
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Old 07-20-2006, 02:41 AM
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Default RE: Backfire on hard accel at 4000 rpm

u check the fuel pressure?

does it smell? running rich?
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Old 07-20-2006, 02:48 AM
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Erik90LX5.0
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Default RE: Backfire on hard accel at 4000 rpm

Not yet but that makes sense ,fuel pump and regulator are stock ,it is weird miss pop sound nad only under wide open throtlle .Thanks
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