87 vs 89 octane

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KeithP

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2022 5.7: at 18k miles I started experiencing a slight hesitation when accelerating from a dead stop. Didn’t matter if the start/stop feature was on or off. This is my 3rd 5.7 and have always just used 87 octane. Both of the other trucks are still in the family. 17 with my son, 19 with my daughter. I know they both still burn 87 octane with no issues. Dealer tried to tell me it may a transmission shift delay. That didn’t make sense to me. Decided it may be a dirty injector issue so…. simple solutions first. I started burning 89 octane. The hesitation went away about half way through the first tank. Still burning it, running about 50/50 city vs freeway driving and averaging 16 mpg (calculated the old fashioned way). Think I’ll stick with the 89 from now on.
 

BenchTest

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As some others might say, I can go on at length about fuel, quality, and it's storage/dispensing. That was my industry for many years.

Let's start simple - is your truck, by owner's manual showing "Use minimum of 87 Octane Fuel"? If so, your truck should be performing "as normal" with 87 octane. Once we answer that, I have a couple of other ideas.
 

Burla

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Gotta check the 2022 but all 4 gens were tuned for 89, and indeed mine doesnt like 87 at all just like yours even worse, but hums on 91. Costco only has 87 and 91 here, so I go 91.
 

Burla

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2022 owners manual. It seams they still tune the hemi for 89, and I can tell you 91 also with be great.

This engine is designed to meet all
emissions regulations and provide
satisfactory fuel economy and
performance when using high-quality
unleaded gasoline ... The use of
89 octane plus gasoline is recommended for
optimum performance and fuel economy
 

Tulecreeper

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2022 owners manual. It seams they still tune the hemi for 89, and I can tell you 91 also with be great.

This engine is designed to meet all
emissions regulations and provide
satisfactory fuel economy and
performance when using high-quality
unleaded gasoline ... The use of
89 octane plus gasoline is recommended for
optimum performance and fuel economy
My owners manual says 87 octane.
 

Mb7640

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I tried 91 for a month and a half did not see a difference between 91 and 89.
 

BenchTest

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As @Burla posted, my readings show 87 is acceptable, but engines are tuned for best performance on 89 or higher (not to exceed 93 octane on factory tune). This doesn't explain the sudden onset of hesitation (use of 87 octane). @KeithP do you typically fuel from the same location? 87 shouldn't cause this. Also, ethanol content of what you're using may be in question as well. Please advise.
 

Curmudgeon

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I've been using 89 octane Top Tier gas, but the place I frequent offer 93 octane for just a couple dollars more per 1/2 tank fill.

I think I'll switch to the 93 for the next 6 months or so, see how the old girl likes "filet mignon" over "ribeye" :cool:
 
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