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  1. #1

    Default Why would my 99 Suburban run better on 87 octane?

    For about a year now everytime she sits in traffic for a bit, I get an intermitent miss... especialy if I have the A/C on. After stopped for a bit upon initial acceleration she misses until she rolls a bit. Fuel pressure good (new pump), new plugs cap and rotor about a year ago. I always put in High test or mid grade.

    This morning I was low on cash so I got the cheapest gas. I drove to work... and not one miss. I drove back in about 100* weather in traffic... and not one miss.

    What happened? I think I read lower octane means the gas will ignite easier... does this imply that I have an ignition issue?
    Last edited by i_build; 06-14-2010 at 05:09 PM.
    Saint Petersburg FL
    1999 SUBURBAN LT C1500
    1987 BMW 325IS
    1994 Infinti Q45
    1997 Nissan Maxima GLE

  2. #2


    I tried a few tanks of the good stuff in mine too. No question it runs better on the cheap stuff. I wrote it off to computer and timing setup for that grade.

  3. #3


    Thanks. Good to know I'm not the only one who noticed this. Thought I was treating her right feeding her the higher octane. It's been a few days now and I still havent felt 1 miss.

  4. #4

    Cool why would my 99 suburban run better on 87

    Unless you have a performance tune installed than 87 is what your stock computer and truck was tuned for.Save your money.

  5. #5


    I could have saved a nice chunk of change. Dont know why I never seen a post about this before... but I have seen a boat load of intermitent idle miss posts...

    Thanks... is this in the faq or sticky sections?

  6. #6

    Join Date
    Feb 2008
    Red Wing, Minnesota, United States


    Simple rule of thumb, always use the lower octane stuff on factory UNLESS the owners manual specifically says to use higher octane. Higher octane needs higer temps to burn off completely, along with upgraded ignition, plugs and so on.
    99 K1500 Suburban LT "THE BEAST"
    Hypertech III, K&N, true dual

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