GEN 2 Engine backfire?

[dude1782]

Mine backfired in S-mode at a low speed. I called my Tech and he said that was no big deal since it was in s-mode which doesn't let the truck shift right away when you get off the gas like it does in Drive. I also did ask about Gas. I have always used Valero 91, he recommended Chevron, Mobil, Exxon or Shell. He said that they are the top-tier gas stations! I put Chevron in and it cost about 20 cents per gal more.
No big deal if it will improve the life of my truck.
Can't find 93 oct in CA.

Home | Top Tier Gas

 

[Monster]

Add me to the list. Filled up 91 octane. Left station in sport mode and after my foot was off the gas for a few seconds, I heard the backfire around 40mph. I pushed the gas, let off and was able to make it happen two more times at that speed. Windows were down for the first time and so it was loud.

Don't think it has ever backfired before. Has 1400 miles. It happened again turning into my neighborhood. And two more times in the neighborhood. I was trying to make it happen.

 

[jakeO]

these trucks use the wide band O2 sensor to see octane. They do not have a in tank sensor so a pop is bound to happen. I think

 

[AvoidTheBoyd]

these trucks use the wide band O2 sensor to see octane. They do not have a in tank sensor so a pop is bound to happen. I think

I think that is a partially incorrect statement. The hydrocarbon-alkane chain that is octane is no longer intact by the time it reaches the O2 sensors and they can not detect octane. It is correct that they do not have an inline fuel composition sensor. Lack of sufficient octane is only "detected" on these trucks by the amount ping the knock sensor is picking up. Fuel with a sufficient octane rating and the knock sensor won't retard timing and obviously with insufficient octane rated fuel and the knock sensor retards timing until the knock subsides.

 

[jakeO]

I think that is a partially incorrect statement. The hydrocarbon-alkane chain that is octane is no longer intact by the time it reaches the O2 sensors and they can not detect octane. It is correct that they do not have an inline fuel composition sensor. Lack of sufficient octane is only "detected" on these trucks by the amount ping the knock sensor is picking up. Fuel with a sufficient octane rating and the knock sensor won't retard timing and obviously with insufficient octane rated fuel and the knock sensor retards timing until the knock subsides.

Yes the O2 sensor does not see the oct but it uses a calculation to determan the oct. So to adjust fuel and timing in combination with knock sensor.

 

[AvoidTheBoyd]

In order for the O2 sensor to detect a difference the air/fuel ratio has to change. In order for the air/fuel ratio to change the specific gravity of the fuel needs to change. The specific gravity of most pump gas varies widely even with the same octane rating. The odds of getting a consistent octane measurement using an O2 sensor is very low. There just isn't enough difference in SG of 87 vs 93 octane. I will agree with you, that it will indicate some overall quality of the fuel.

 

[Black&GreenRaptor]

I'm having a similar issue every time I fill up my tank I use 91-93 whichever I can find and when I drive off it randomly pops like 5 or 10 times then stops it happens in normal and sport mode and when I'm on and off the throttle


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[CCole77]

This "backfire" happened to me as well this week. I was slowing down for traffic on the highway and it popped.. Did it again as I was slowing down going into my neighborhood. I have only put one tank of gas in it since if was filled up by the dealer and I used premium 93 oct and I was at about 1/4 tank when it happened and I do not remember it happening earlier in the duration of that tank of fuel.

I had recently put i an Airaid drop in filter and SPD turbo adapters...hope it is not related to either one of those. I have changed the filter back to the stock one to see if that has any effect.

Anyone else have any solutions or found the cause of this propblem?

 

[MTheory]

Why is this considered a problem? Coming from an Biturbo E63 AMG, it popped and backfired on deceleration and between shifts on a daily basis. Just what high-performance turbo vehicles do from what I've seen owning my share over the years.

1800 miles on my 2018 and haven't experienced this though.

 

[MGD]

Backfired on a consistent basis are a sign of an issue though. Occasionally is nothing to worry about.