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Timing

Discussion in '4th Gen 4Runners (2003-2009)' started by BillC523, Feb 15, 2021.

  1. Feb 15, 2021 at 11:07 PM
    #1
    BillC523

    BillC523 [OP] New Member

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    Had timing belt, idler pulleys, water pump, etc. replaced on 4.7L v-8 4runner. Was getting 15-15 1/2 MPG before work. Getting 12 MPG now. Thought I would clean injectors, put 2/3 gallon of #1 diesel in tank with full tank of gas. Ran great, more power, 21 miles per gallon mileage. Discovered that would harm engine. Haven’t done that since. Was told it shouldn’t run well with that mix of diesel in the tank. So, what is the solution to get back to decent gas mileage?
     
  2. Feb 15, 2021 at 11:54 PM
    #2
    Moon Landing

    Moon Landing AFFTC 1967/68 Eddies Air Patch

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    Diesel is not good for a catalytic converter, but in the amount you're talking about, and depending on how many miles and how worn your engine is? It may or may not be the death knell for your cat. Do some research - possibly starting with Bob the oil guy.

    Your MPG change is most likely a result of a change in timing after the belt install. imo
     
    Last edited: Feb 16, 2021
  3. Feb 18, 2021 at 3:08 PM
    #3
    BillC523

    BillC523 [OP] New Member

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    You mentioned change in timing. I’m not familiar with how the timing is set on a 4.7L v-8. Are there several timing adjustments on this engine?

    another question:
    I had planned on changing out the stock muffler and resonator for a steel pack muffler by Brockman. It’s simular to the cherrybomb straight through muffer...

    Does the 4.7L engine require a certain amount of back pressure to run efficiently and also will running the Brockman muffler damage the engine in any way?
     
    Last edited: Feb 18, 2021
  4. Feb 18, 2021 at 3:15 PM
    #4
    Moon Landing

    Moon Landing AFFTC 1967/68 Eddies Air Patch

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    This will answer your question better than I ever could, on here.

    https://www.youtube.com/watch?v=HPpzLJwoxng

    .
     
  5. Feb 19, 2021 at 8:38 PM
    #5
    BillC523

    BillC523 [OP] New Member

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    Moon landing thanks for your help with the video.
    One other issue, I would like to remove the stock muffler and resonator and replace with a Brockman steel pack muffler. It’s a straight through design similar to the old Smitty mufflers used back in the 50’s. My concern is does the 4.7L engine require a certain amount of back pressure to run properly and not damage the engine in any way?
     
  6. Feb 20, 2021 at 7:05 AM
    #6
    Moon Landing

    Moon Landing AFFTC 1967/68 Eddies Air Patch

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    There's a general rule on that kind of mod - intake or exhaust? One or the other. Doing both in many/most instances will require at minimum, a retune. jmy2c - others opinions may be of a different viscosity.
     
  7. Feb 20, 2021 at 7:27 AM
    #7
    BillC523

    BillC523 [OP] New Member

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    What is entailed in a retune?

    What I had thought about doing was change the intake filter to one that allowed the engine to breath better and change the exhaust system as noted.
     
  8. Feb 20, 2021 at 7:43 AM
    #8
    Moon Landing

    Moon Landing AFFTC 1967/68 Eddies Air Patch

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    The internet is rife with answers. I suggest you Google it.
     

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