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07 gt running really bad after 4 days of no mufflers

498 Views 9 Replies 6 Participants Last post by  KATO, 
PedroAlvarez
Ok, i’ve got a 2007 mustang gt with the JLT intake long tube header gutted cats to 3 inch pipes all the way back to the axle. i’ve recently taken the mbrp mufflers off the car and am running straight pipes and after 4 days of nothing out of the ordinary the car started running horrible at the gas station while filling up. I barely got it home. Next morning i read the codes for the now appearing check engine light, both banks are running lean and if i hold the rpm’s at 3 i can hear it popping constantly. the car idled fine the next morning for 30 mins until i cleared the codes, after that it ran like garbage. I just bought a tuner and believe it is a tune issue. I’m really new to this stuff
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crjackson
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Recon
What tune do you have? Might’ve gotten some bad gas. But it sounds like there’s an air leak somewhere potentially.


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PedroAlvarez
Recon said:
What tune do you have? Might’ve gotten some bad gas.


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nah it happed right before getting gas
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Recon
Ok. Who’s tune do you have for your car? I’d check for air leaks too.


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PedroAlvarez
Recon said:
Ok. Who’s tune do you have for your car? I’d check for air leaks too.


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unknown tune but i’m gonna get retuned for the new exhaust setup. where would be the most common air leak spot
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Recon
Look over your complete intake system. What are the actual codes?


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Yuli
Also consider O2 sensors in exhaust are damaged due to shock waves. On key cycle, with MIL condition asserted, ECM defaults to a "safe" openloop burn setting. When you clear, it tries to go back to closed loop using the damaged sensor.
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Dino Dino Bambino
Since the engine's been running lean on both banks since you removed the mufflers, it would seem a no brainer to reinstall the mufflers.
Unless you want to suffer hearing loss, annoy the neighbors, or attract the unwanted attention of the boyz in blue, DON'T leave the car straight piped. Your 3" pipes are also way overkill for a N/A set up.
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KATO
I'm leaning more towards your Tune, and agreeing with Dino Dino.
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