Backfiring on downshift?

[TravisHTX]

Hey all,

Just curious if any of you all have noticed this before? I had the truck on the beach this last weekend, in Baja mode, when I would be 3rd gear, and let off off the throttle/engine braking to slow down, and the engine would downshift to 2nd gear, about 2 out of 3 times, I would hear a small pop from what sounded like it was coming from the exhaust. It would also do it from 2nd to 1st.

I didn't get a chance to test 4th to 3rd... Tide was too high, and beach too rutted up.

When I was back on concrete, I put it in normal mode, and did not notice the popping noise anymore. But again, I did not specifically try to reproduce the issue since I didn't want to risk any break down/limp mode that far from a convenient tow. Maybe later today if I have time, I will see if I can reproduce it with Baja, sport, or normal modes while on concrete.

About 4 weeks ago, I was on the same beach, running the same PSI (20 PSI), and I do not recall hearing any popping.

The truck is completely stock mid 2019 build, and running 93 octane (according to the pump).

 

[RW17FX4]

not exactly the same conditions, but my 17 will sometimes backfire at slow rpm downshifts around 10-15mpg AFTER the fuel tank is filled up. again i’m sure this is totally different, but just wanted to mention

 

[TravisHTX]

not exactly the same conditions, but my 17 will sometimes backfire at slow rpm downshifts around 10-15mpg AFTER the fuel tank is filled up. again i’m sure this is totally different, but just wanted to mention

Yea, slightly different, but good info though that its not isolated to 1 particular scenario. I am assuming in your case, it might be due to timing adjusting with different fuel. I haven't heard backfiring while on concrete in any mode so far, even after a recent fill-up, so the popping this weekend surprised me. Its possible the fuel I got was just really different than what I normally get, I had never stopped at that particular gas station before.

Disclaimer, my engine expertise stops at, "that don't sound right", and "I read on the inter-webs that...".

Baja mode leaves the throttle plate open to keep the turbos spinning when you let off the gas (so they spool faster when you get back on the gas). The truck is always going to be more likely to pop on decel in that mode.

Good info. I knew the throttle response was different in Baja mode, I didn't know about it keeping the turbos spinning though. I just wanted to be sure that a little light backfiring is not something to be concerned about!

 

[FordTechOne]

Hey all,

Just curious if any of you all have noticed this before? I had the truck on the beach this last weekend, in Baja mode, when I would be 3rd gear, and let off off the throttle/engine braking to slow down, and the engine would downshift to 2nd gear, about 2 out of 3 times, I would hear a small pop from what sounded like it was coming from the exhaust. It would also do it from 2nd to 1st.

I didn't get a chance to test 4th to 3rd... Tide was too high, and beach too rutted up.

When I was back on concrete, I put it in normal mode, and did not notice the popping noise anymore. But again, I did not specifically try to reproduce the issue since I didn't want to risk any break down/limp mode that far from a convenient tow. Maybe later today if I have time, I will see if I can reproduce it with Baja, sport, or normal modes while on concrete.

About 4 weeks ago, I was on the same beach, running the same PSI (20 PSI), and I do not recall hearing any popping.

The truck is completely stock mid 2019 build, and running 93 octane (according to the pump).

Absolutely normal. What you're hearing is not actually a "backfire"; it's un-burnt fuel being pushed out on the exhaust stroke and combusting in the manifold. This typically occurs when the throttle is closed quickly after low MAP/positive boost conditions (heavy load/acceleration), causing excess fuel in the cylinder with an overly rich mixture.

Baja mode exemplifies this condition due to the aggressive PCM operating strategy and the TCM holding gears when the throttle is released.

 

[TravisHTX]

Absolutely normal. What you're hearing is not actually a "backfire"; it's un-burnt fuel being pushed out on the exhaust stroke and combusting in the manifold. This typically occurs when the throttle is closed quickly after low MAP/positive boost conditions (heavy load/acceleration), causing excess fuel in the cylinder with an overly rich mixture.

Baja mode exemplifies this condition due to the aggressive PCM operating strategy and the TCM holding gears when the throttle is released.

Thank you for your response. Good to know the detailed reason behind the popping noise. That makes perfect sense. The time when the popping was the worst was when I was on a narrow section of beach at high tide, timing waves. Lots of flooring it involved!

 

[NHDude4]

Yep, I experience this in my '18 (normal and sport modes). I have the Corsa resonator delete which makes it more obvious. With the windows down and rear slider open I notice it all the time on throttle lift when at low speed/low gear in parking lots. I'm sure it does it all the time and it's just hard to hear from inside at higher speed or with the windows up.

 

[TravisHTX]

Yep, I experience this in my '18 (normal and sport modes). I have the Corsa resonator delete which makes it more obvious. With the windows down and rear slider open I notice it all the time on throttle lift when at low speed/low gear in parking lots. I'm sure it does it all the time and it's just hard to hear from inside at higher speed or with the windows up.

It's reassuring to know that my Raptor isn't "special"! When I was hearing it for the first time this weekend, I thought I had a service department trip in my near future.

 

[RaptX4]

Good insights; I found early in on my 2018 SCREW it'll backfire repeatedly on 'cheap' gas (< 93). This weekend though I've run into an issue of it backfiring at a near stop after strong acceleration and hard breaking - and only popping out of the right exhaust. Any ideas? Fixing to find this thing a new owner and go the route of a Super Duty tremor. Also waiting on new front Fox struts as the factory versions have been rattling like a bag of marbles for past 20,000 miles (48K now) - they are backordered indefinitely.
Finally did remedy the rattling pano moonroof with a trip to the dealership who subbed it out to local upholstery shop to have the factory bulletin fix completed on the roof.

Ford for life, but this Raptor is killing me.

 

[RamseyF]

the popping from the exhaust on the raptor is no different then when you hear sports cars do it when they get the rpms up and let the gas off. except those they design the exhaust and tune to make that happen more aggressively. absolutely normal.

 

[RaptX4]

Thanks RamseyF - do you agree there is a definite need to run premium gas in the Gen 2 Raptor's 3.5 for over the road driving? I've been on premium since about 5K miles to remedy repeated backfiring. The acceleration and hard braking just started over the weekend.