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Bad misfire at idle...

Discussion in 'Stock 2002 - 2005 Explorers' started by shadowless127, November 30, 2017.

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    1. shadowless127

      shadowless127 Well-Known Member

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      This pertains to my 04 Aviator...

      So for about the past year every 6-8 weeks Cylinder 6 would miss once then never do it again. Mechanic A confirmed what I was thinking and said the coil was most likely dying and that as long as it's not doing it very often to just leave it till it worsens. Cut to the end of September and I'm getting ready to take a 6hr each way trip to Penn State to go to a football game so I figure let's just change it out now and not worry about it. So I have Mechanic B (who has done tons of great work for me over the last 5 years) swing by and swap out the Cylinder 6 coil and plug (even though the plug was only a year old). This is where it all starts going downhill. We start getting misfire codes for Cylinder 6 at a rate far far far worse than previously. So we get back from Pennsylvania and I take it to Mechanic A to look at since I can just drop the truck off and pick it up after I get out of work (I commute via train and Mechanic A's shop is right in the parking lot for the train station by my dad). He see's the misfire, cleans the MAF, cleans the TB, resets the fuel map, drives it around and it improves a lot. Still not a 100% smooth but honestly at 145K miles it's smooth enough and he said there was nothing of concern on his Live-OBDII while he was driving it.

      So I drive it around for about a month and a half with no issues; no misses, no CELs, no nothing. So last week we take it 3hrs to the Poconos for Thanksgiving. Drives great the 160mi there and drives great the 160mi back; no misses, no CEL, nothing. So about 4hrs after I get home I go out and run some errands and grab some dinner aaaaaand then it starts missing and throwing a CEL For misfire detected on startup and cylinder 6 misfire. ffffuuuuuuuuuuuuuuuuuuu.... But the thing is, it only does it when idle, and if it starts missing and the CEL starts flashing, if i start driving and give it throttle it just clears up. And I can be sitting at a light and it can be idling perfectly and then BAM it starts missing. But I never have any misses when I'm driving or on the highway cruising, but if I stop at a light it's like a coin flip if it's gonna start missing.

      Could this just be something like a clogged fuel filter or a weak/clogged injector? I don't think it's something catastrophic since it only started happening after I had the coil changed, and about 2 weeks before it was changed I drove to south jersey and Philadelphia with no issues.

      P.S. I hate cars....but I love them....but I reaaaaalllly hate them.
       
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    3. Gilligan

      Gilligan New Member

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      Had a similar issue for over a year a couple of years ago. Pesky miss only at idle. Finally pulled the throttle body and gave it a good cleaning making sure I got into everyone of those tiny little passages. After it dried for the night I installed it and it has never come back.
       
      Last edited: December 5, 2017
    4. shadowless127

      shadowless127 Well-Known Member

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      Was this miss on a single cylinder or random?
       
    5. Gilligan

      Gilligan New Member

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      Single cylinder. #5
       
    6. Number4

      Number4 "I'm counting to 3, then I'm getting your dad." Elite Explorer

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      You mean #6?

      Might have the injector checked out. Including wiring
      Compression test.

      It takes 1000 misses to throw a code.
      One misfire won’t necessarily be felt at highway speeds, even though it’s missing.

      You can swap the new coil to a different cylinder and see if the miss moves. Though unlikely, you could have a bad new coil.
       
    7. TechGuru

      TechGuru Well-Known Member

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      Compression test.

      Check the valves with a boroscope.

      Use only top tier gas and run a tank with techron added.
       
    8. shadowless127

      shadowless127 Well-Known Member

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      Took it to Mechanic A Monday night as I didn't need a car yesterday because it was my company's Christmas party so I was planning on getting loaded and not driving so it worked out well.

      He said the coil is a dud. He also said he doesnt feel it's an internal engine issue.

      I only ever run top tier 93-octane in it. I dumped Liqui-Molly Jectron in the tank that is currently in it.
       
      Last edited: December 6, 2017
    9. shadowless127

      shadowless127 Well-Known Member

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      Picked it up last night, put about 80mi on it, 25% city 75% highway. I honestly don't remember the last time this thing idled so smooth and drove so good. Saw an instant gain in MPG as well.
       
    10. IIGood

      IIGood Active Member

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      Okay, this kind of bothers me. Why is this a thing now? Why aren't all gas stations on the same level, even within the same brand? This "Top Tier" nonsense just seems so ridiculous to me. I can only surmise one answer... $$$$$$$$$$$$$$$$$$$$$
       
    11. TechGuru

      TechGuru Well-Known Member

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      It's not really a thing now...it's been a thing since 2004...

      In 2004 representatives of BMW, General Motors, Honda, and Toyota got together to specify what makes a good fuel. Using recommendations from the Worldwide Fuel Charter, a global committee of automakers and engine manufacturers, they established a proprietary standard for a class of gasoline called "TOP TIER" Detergent Gasoline The new standard required increased levels of detergents, and restricted metallic content. Volkswagen/Audi joined the group of automakers in 2007. Gas brands can participate and get a TOP TIER license if they meet certain standards, which includes performance tests for intake valve and combustion chamber deposits, fuel injector fouling, and intake valve sticking. Additive manufacturers pay for the testing, the cost of which varies from year to year, while gasoline companies pay an annual fee based on the number of stations it operates to participate in the program.

      http://newsroom.aaa.com/2016/07/aaa-not-gasoline-created-equal/

      http://newsroom.aaa.com/wp-content/uploads/2016/07/Fuel-Quality-Fact-Sheet-FINAL.pdf

      http://www.aaa.com/AAA/common/AAR/files/Fuel-Quality-Full-Report.pdf

      http://newsroom.aaa.com/wp-content/uploads/2016/07/Fuel-Quality-Infographic-1.png

      http://newsroom.aaa.com/wp-content/uploads/2016/07/Fuel-Quality-Infographic-2.png

      Most of the major gas retailers are TopTier, just avoid Walmart and grocery store gas and the few no name ESL (English as a Second Language) type owner 1 man operation type places.

      [​IMG]

      We actually have a scammer chain (Alon ex Fina) out here selling 86 octane to be able to have their prices "appear" to be much lower than all the other fuel stations in town. Most if not all modern vehicles require 87 octane at a minimum (our explorers do!). So after driving up to the pump and seeing it's only 86 one has to get the "plus" 88 or "premium" 90 to meet the required octane requirements. Also any car I've seen that requires premium requires at least 91 minimum so this chain would not even be able to provide anything for those.
       
    12. imp

      imp Well-Known Member

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      I fail to see how a problem with the Throttle Body could cause misfiring in one cylinder only. It valves in only air, distributed to all the cylinders through mostly equal-length passageways. I am presuming the Aviator has the same drive by wire TB as Explorer? imp
       

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