Engine Backfire

blue_roster_cult

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I have a 2018 approaching 150k. I have a bad backfire (gunshot) after filling up with fuel. I do not top off the tank, and last time I got fuel I stopped a few gallons short. The back fire actually broke the muffler internally.

Couple things: my cats are removed and the sensors turned off for reasons I posted elsewhere. Car has been like this for a few months without issue. Also, I have an o2 sensor that throws a code off and on. But this code also preceded the backfire issue.

Again, this only happens after fueling up. Any thoughts?
 

JasonH

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Try getting your air/fuel and exhaust temp data from the ECU. If your cats are off, maybe the vehicle is not seeing something it expects to see and is running rich?
 

LokiWolf

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Is it tuned, or just stock tuning with the sensors turned off? What ever is causing the post detonation is going to break something more than the muffler if it continues. It is probably doing it more than when you fuel, but things are hot, because, well you drove to the gas station causing the post detonation.
 
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blue_roster_cult

blue_roster_cult

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Seems to be a common issue with Raptors and 150s


 

LokiWolf

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Seems to be a common issue with Raptors and 150s


Interesting!
 

LokiWolf

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So, saying it is common is a LARGE jump. 1 dude with a Coyote powered 150, and a few Raptors. Would not call that even vaguely "common". The 150 forum guy never posted a solution. Neither did the raptor guys really. I have been driving Expeditions and on these forums since 2016, other Fords before that. I also run around on the 150 forums, cause well I own one. Never had seen this before.

One mention was of O2 sensors detecting incorrectly. Since yours are turned off completely that could contribute. Seems it could be fuel vapor separator and canister purge valve related also. If those aren't operating as expected. Sounds like a few paths to go down.
 
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blue_roster_cult

blue_roster_cult

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Two more threads (no solutions):

 

apex96

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This is not a common issue at all. If you've removed your cats and O2 sensors, and have not tuned for such your vehicle is more than likely trying to compensate by dumping fuel into the intake track. The ECU will default to running rich as a way try and prevent a lean condition from severely damaging the engine. Take it to a proper tuning shop and have them create a customs mapping that takes into consideration the modifications you’ve made.
 

2020FordRaptor

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Seems to be a common issue with Raptors and 150s


Not common at all. Like @apex96 said, take it to get tuned since it is going to run rich.
 
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blue_roster_cult

blue_roster_cult

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This is not a common issue at all. If you've removed your cats and O2 sensors, and have not tuned for such your vehicle is more than likely trying to compensate by dumping fuel into the intake track. The ECU will default to running rich as a way try and prevent a lean condition from severely damaging the engine. Take it to a proper tuning shop and have them create a customs mapping that takes into consideration the modifications you’ve made.
Thanks. Again, this ONLY happens after a fuel-up. What’s the correlation with the tune?
 
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