Car Issue Input

Discussion in 'The Powder Keg' started by austinjoe13, Aug 9, 2020.

  1. austinjoe13

    austinjoe13 <------------<<<-

    I'm hoping to get a little input on a misfire in my girlfriend's car. It is intermittent. On a cold start, there are no issues. When the vehicle turns off, or returns to a lower rpm, the CEL starts blinking, and you can feel the engine shudder. Every now and then, there's a small backfire through the exhaust, it seems.

    Vehicle Info: 2009 Mercury Mariner AWD with 3.0L V6

    Codes: Cyl 4 Misfire, Cyl 4 Injector Circuit, Bank 2 Lean

    This afternoon, I switched the #4 and #5 coils around and checked the spark plugs. They are worn, but the color is good. The test drive yielded no changes. The same codes came back after being erased.

    I would say, at this point, that the #4 injector is bad, or has issues when it is hot. Has anyone had similar issues with other Ford vehicles, or maybe solved a similar issue? Thanks.
    TXplt, ChaZam, BigEd63 and 1 other person like this.

    SUBMOA G&G Evangelist

    If it is not too difficult, swap #4 injector with one close to it and clear codes . Start and run it and see if your code changes to the cylinder you swapped injectors with.
    neophyte, TXplt, Cyrano and 2 others like this.

  3. ChaZam

    ChaZam G&G Evangelist Forum Contributor

    Or check the wiring and connector for that injector. Possibly it's not making a secure connection all the time or something like that.
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  4. blue fox

    blue fox G&G Evangelist

    Run a few cans of injector cleaner through it and see what happens. also how many miles are on it? If it is worn enough you might have something else like valves starting to get burned off. I had a 2000 Ranger with that engine that started developing the same type of problems. Drove my mechanic crazy trying to solve it. Injector cleaner helped for a while but I finally got rid of it this year because we were looking at the possibility of A rebuilding the engine or B replacing the engine with a rebuilt one. either way we were looking at about $4k-5k cost wise
  5. austinjoe13

    austinjoe13 <------------<<<-

    That will be my next step, but I might have to pull the intake manifold off to do it. That’s not too big of a deal. I’ll probably do spark plugs at the same time.

    Wiring seemed solid. I’m pretty impressed by Ford’s wiring harnesses compared to Jeep’s. Ford looms everything, then wraps the looms. Nothing was broken.

    Injector cleaner will be in the near future. It has just shy of 190k miles. I have a hard time thinking that it’s a valve issue since it’s so intermittent, but I will definitely be keeping it in mind.
  6. TXplt

    TXplt Gun Toting Boeing Driver Forum Contributor

    Sounds like the injector isn’t getting power or is bad. Backfire possibly due to lean mixture in the cylinder.

    My first thought would have been coil as well. Had a bad coil on a mustang years ago and I’d get power loss over certain RPM range as well as a kind of backfire but not really. Intermittent coil caused the unburned fuel/air charge to be expelled into the exhaust manifold where it would later ignite.
  7. Txhillbilly

    Txhillbilly G&G Evangelist

    I'd say it's the injector going bad/clogged. I have a Chevy Colorado with a I-4 cylinder engine. If I ever lug the motor taking off from a stop,it will throw the same code.
    I just clear it,and keep driving it. Once the injector finally gives up,I'll change it.
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  8. blue fox

    blue fox G&G Evangelist

    If I remember correctly, my mechanic also said mine was the no. 4 cylinder. He swapped wires, coils and even put new wires in.
    neophyte, ChaZam and jwrauch like this.