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Thread: Lean on 1/8 to 1/4 throttle.

  1. #1
    DX User
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    Apr 2009
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    1989 Honda Accord LX
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    Hamilton Canada
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    Lean on 1/8 to 1/4 throttle.

    Is it normal or I have a problem?
    When engine is cold a/f meter slowly goes up from 0 until it reaches end of stoich. Then I press the gas and rpms drop to idle but mixture drops as well to mid of lean. I wait until engine warms up and take off. a/f meter stays in mid lean on slow acceleration but once I pass 1/4 a/f jumps to edge of rich and stays there. When I let go the gas a/f jumps back to 1/2 lean. Sometimes when I cruse on 1/8 throttle I have 0. On hard acceleration I have 1/4 rich.

    O2 sensor is new.

    I bypassed temperature valve for second carb barrel and now I have more average stoich. But still on 1/8 trottle I have lean.

    When engine is warm idle is jumping around stoich area but sometimes it doesn't and stays in lean area. My old O2 sensor when I took it out was in white ash.

    Any idea? pump? vacuum leak?

    Also I need some time to start car in the morning. Takes about 10 seconds cranking starter before car comes to live. And even then when I take off it can stall.

    Thanks



  2. #2

    A20A1's Avatar
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    Re: Lean on 1/8 to 1/4 throttle.

    Is it a wideband O2 sensor?

    If I remember correctly the sensors also need to warm up to a proper operating temp too before they give accurate results.
    - llia


  3. #3
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    Re: Lean on 1/8 to 1/4 throttle.

    Quote Originally Posted by A20A1 View Post
    Is it a wideband O2 sensor?

    If I remember correctly the sensors also need to warm up to a proper operating temp too before they give accurate results.
    No standard NKG O2 sensor for Honda accord 1989 LX but I will check maybe it is.

    But readings are the same even after driving for 1 hour. The only difference I noticed that after long drive idle stays 90% of the time in stoich. I remember from my old days tuning my car I always programmed ECU to be always in stoich or little in rich zone. Basically it never dropped below lowest stoich mark no matter what conditions are. Turbo boost no boost, idle.But it was Injection. Should carb ever drop to lean?

  4. #4
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    Re: Lean on 1/8 to 1/4 throttle.

    Adjusted the float level and idle mix. Now mix on idle is perfect and stays around middle of stoich. Now car starts no problem. Also warming up procedure is fine too. Fast idle is around 2500rpm and then after pressing gas it drops to ~800rpm. Mix gauge shows no problem. The problem starts when I shift into gear and press gas. Mix gauge drops to 0 (super lean) When I let gas go it jumps back to normal. Under hard acceleration mix goes to normal and stays there for entire acceleration but If I press gas less then 1/2 then mix gauge goes up slowly from 0 to normal. And I reach normal mix around 3000rpm.
    Car accelerates hard and fast. For ~90hp it is good but that lean cruising condition. If I drive on a empty highway at night I can have super lean for entire trip. But again when I press gas hard it jumps to normal mixture. Then I let it go and press gas about 1/8 it jumps back to 0. Any idea?

  5. #5
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    Re: Lean on 1/8 to 1/4 throttle.

    Fixed the problem. First it was a cracked air jet hose. Replaced it. Airbox is replaced with a open filter mod. EGR return to carb air box is disconnected. Now it pulls very hard. Mixture stays in stoich area even under light acceleration. Adjusted idle mix as well. Now it's in stoich region. Will try to plug ERG hose back. Will see if it will make a difference.

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