Engine Backfire

[blue_roster_cult]

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]

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]

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.

 

[blue_roster_cult]

Seems to be a common issue with Raptors and 150s

2018 - backfire only after fill up? Fuel puddling? - Ford F150 Forum - Community of Ford Truck Fans

2015 - 2020 Ford F150 - 2018 - backfire only after fill up? Fuel puddling? - I have a 2018 5.0L When i fill up the truck i get a back fire out the exhaust. If i pump more fuel in after it clicks full it will always backfire. If i add fuel but don�t fill the truck it does not. thoughts?

www.f150forum.com

GEN 2 - Exhaust backfire?

Hello All, Has anyone had issues with exhaust backfire after gassing up? Details: Only gassed up 6 times since I bought in November 2018 (2017 model It was used with 9k miles) (I travel during the week most weeks low miles lol) The last 4 times I have gassed up exhaust pops upon deceleration...

www.fordraptorforum.com

 

[LokiWolf]

Seems to be a common issue with Raptors and 150s

2018 - backfire only after fill up? Fuel puddling? - Ford F150 Forum - Community of Ford Truck Fans

2015 - 2020 Ford F150 - 2018 - backfire only after fill up? Fuel puddling? - I have a 2018 5.0L When i fill up the truck i get a back fire out the exhaust. If i pump more fuel in after it clicks full it will always backfire. If i add fuel but don�t fill the truck it does not. thoughts?

www.f150forum.com

GEN 2 - Exhaust backfire?

Hello All, Has anyone had issues with exhaust backfire after gassing up? Details: Only gassed up 6 times since I bought in November 2018 (2017 model It was used with 9k miles) (I travel during the week most weeks low miles lol) The last 4 times I have gassed up exhaust pops upon deceleration...

www.fordraptorforum.com

Interesting!

 

[LokiWolf]

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.

 

[blue_roster_cult]

Two more threads (no solutions):

Possible Backfire...weird pop noise

From time to time when coming to a stop or to make a turn my truck sounds like it has a slight backfire or pop coming from the rear of the truck. Does not do it all the time and is hard to replicate, but have heard it a couple of times now. I have the SPD turbo adapters installed and just put in...

www.fordraptorforum.com

GEN 2 - Engine backfiring?

So I just fueled up, I've been putting in 89 octane. And on my way home maybe less than 3 minutes, I pull up to a stop sign and I heat two POPs, and didn't think anything of it. I come to another stop sign and hear another POP. Is this sound the engine backfiring? Any reason it would do this...

www.fordraptorforum.com

 

[apex96]

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]

Seems to be a common issue with Raptors and 150s

2018 - backfire only after fill up? Fuel puddling? - Ford F150 Forum - Community of Ford Truck Fans

2015 - 2020 Ford F150 - 2018 - backfire only after fill up? Fuel puddling? - I have a 2018 5.0L When i fill up the truck i get a back fire out the exhaust. If i pump more fuel in after it clicks full it will always backfire. If i add fuel but don�t fill the truck it does not. thoughts?

www.f150forum.com

GEN 2 - Exhaust backfire?

Hello All, Has anyone had issues with exhaust backfire after gassing up? Details: Only gassed up 6 times since I bought in November 2018 (2017 model It was used with 9k miles) (I travel during the week most weeks low miles lol) The last 4 times I have gassed up exhaust pops upon deceleration...

www.fordraptorforum.com

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

 

[blue_roster_cult]

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?

 

[apex96]

More then likely fuel has puddled up in the cylinder and when you restart a hot vehicle that extra fuel gets pull through without being combusted. The exhaust is still hot and once the fuel hits the exhaust it ends up igniting.

 

[armoredsaint]

Some people pay good money for that option

 

[blue_roster_cult]

More then likely fuel has puddled up in the cylinder and when you restart a hot vehicle that extra fuel gets pull through without being combusted. The exhaust is still hot and once the fuel hits the exhaust it ends up igniting.

No… It ONLY happens after refuel. I can drive all day, go to the store, go to eat, go anywhere, and then if I stop for gas and fill up, it backfires. An issue shared by many per the 4 threads I posted. It’s not a tuning issue.

 

[blue_roster_cult]

Some people pay good money for that option

It actually is hilarious. Yesterday I was passing by a road crew of convicts and it sounded like a 12-gauge went off. They probably all got a good pat down after that.

However, the wife doesn’t think it too hilarious.

 

[rd618]

No… It ONLY happens after refuel. I can drive all day, go to the store, go to eat, go anywhere, and then if I stop for gas and fill up, it backfires. An issue shared by many per the 4 threads I posted. It’s not a tuning issue.

More than likely it’s evap system related due to your lack of sensor readings. Like others posted it’s running rich. When you fill the evap and emissions systems reset slightly when you add more fuel. It’s based on how much fuel fills the tank and how much you had before. In simple terms they monitor the amount of gas that evaporates and how much of a vacuum you hold.
If you want to test this. Drive down to 1/4 tank. Then put half to 1 gallon in. Re start. Nothing will likely happen. Put in more and you will notice the same behavior you have now.

 

[LokiWolf]

Let's sum up.

You called it a "Common" issue, it isn't. PERIOD.

You have been given 2 things that could be causing it, O2 Sensors being disabled because of no Cats, and the EVAP system. In reality, it is most likely a combination like was mentioned above. Hot Exhaust, Rich condition, Nocats, and EVAP system not working at 100%. If you are running without cats, and the sensors are turned off with out any other adjustments, it will make the issue worse, because the systems is defaulting to rich.

Get a proper tune for no Cats(Which the best tuners out there won't touch with a 10ft pole), or put cats back on and turn sensors back on. Also looks like maybe inspecting the EVAP system and make sure everything is working as good as it can? You asked for help, we are offering it. You want this to be unrelated to what you have done, but it most likely isn't.

 

[purevw]

No… It ONLY happens after refuel. I can drive all day, go to the store, go to eat, go anywhere, and then if I stop for gas and fill up, it backfires. An issue shared by many per the 4 threads I posted. It’s not a tuning issue.

It takes 5 minutes to refuel. The store, eating, etc., usually take longer than that. Timewise, they are not comparable.

 

[blue_roster_cult]

For anyone interested, here is what the backfire did to the muffler. It blew this baffle (which should be square with the cut lines) out of place. This definitely did not result in a performance upgrade.