Engine Knock After Fill Up

[Dadawada]

On rare occasions, I've noticed engine knock at certain RPMs. Tonight, I filled up with gas at a different station than usual, a BP. I usually fill up at an Exxon near my home. I do always fill up with Premium.

After filling up at the BP station I had a noticeable loss of power. I also noticed the engine was knocking more than normal. Eventually after a few miles, this went away. Just curious if this was a case of bad fuel or if I may have a sensor going bad.

2018 JLUR 3.6 with 65,000 miles

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[m3reno]

BP is crap gas. I always use Exxon or Shell. I had some knocking issues in the summer months and recently changed my PCV valve to the updated version and have 0 issues now even with 87. I'll know more once the weather warms up as that's when I had the low rpm knock.

 

[Deleted Member RoadNomad]

Since you always use premium I wonder if the fuel you got at BP was crap or lower octane then the engine was use to having it in.

With Premium the timing will be advanced much more and if the engine tries to use that much of an advance it will more than likely ping or experience a detonation knock. More then likely the engine re-adjusted the advance much lower to accommodate the crappy fuel and prevent engine damage from the detonation.

Take a run to autozone or oreilys and pick yourself up some octane booster and add it to the remaining fuel. If it is a fuel issue all your problems should totally disappear, the ECU will re-adjust the timing for the higher octane and your performance should return.

I have had issues like your describing while on some road trips, I use to keep a bottle of 104+ octane booster in the back storage area just in case I had a repeat of crappy gas.

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