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In this video I jumped the gun on a misfire diagnostic. I made an assumption based of pattern failures and it cost me an hours time. It doesn't sound like much but it is frustrating to me because I hate wasting time and making assumptions that are made with out gathering data. Any how, problem solved. -Enjoy!
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48 thoughts on “Stick to your diagnostic game plan!!”
  1. Avataaar/Circle Created with python_avatars MarioDIY says:

    My 2005 Pilot is exhibiting the same symptoms except I'm only getting a p0172 and misfire CEL, misfire codes mainly in Cyl 1 & 3. Mine has 233k miles.

    I've been chasing the rich code with no avail. My fuel trims are normal when accelerating, once I'm at idle or coasting i can see my STFT on Bank 1 go from -3% to -20-25%. Injectors are not leaking. Checked with an oscilloscope. Cylinders were dry. I already have 3 new injectors reading 11.3 ohms. I'm replacing all 3 injectors on Bank 1.

    I hope to call it fixed! This video alone helped me pinpoint that 1 or more injectors on Bank 1 are failing. Not as bad as this one but it's getting there. Bank 2 runs fine. Slightly lean at +2% for both ST and LT FT.

  2. Avataaar/Circle Created with python_avatars Alexander Cahoulan says:

    I search for Eric O. honda v6 videos. How have I never seen this video? I even searched his page. I guess it is exciting to find it randomly though. lol

  3. Avataaar/Circle Created with python_avatars John E. Carr says:

    Another great video.

  4. Avataaar/Circle Created with python_avatars Derek Simenac says:

    Makes sense if they share power and one is shorted that then all injector powers will go to the short, its not isolated.

  5. Avataaar/Circle Created with python_avatars John Atkins says:

    A man who makes no mistakes is not working at all, an old guy I worked with told me believe nothing any one tells you and only believe half what you see. I have set off with a broken down machine with perceived ideas and finished up the wrong tree

  6. Avataaar/Circle Created with python_avatars Bill Scott says:

    Hi Eric, You explain it very well. It can be a buzzer to finding the problem.

  7. Avataaar/Circle Created with python_avatars Nicholas Andre says:

    This sounds like the wonky injector is causing ridiculous fuel trims with the O2 sensors. The longer you go, the worse the fuel trims on the good injectors get and the misfires begin.

  8. Avataaar/Circle Created with python_avatars bass MD says:

    It’s a “Jump-to-conclusion” mat; you literally Jump to conclusions.

  9. Avataaar/Circle Created with python_avatars Brian Hind says:

    Eric: I am NOT a mechanic, even if I do troubleshoot & repair quite a few agricultural implements here where I live. I know nothing about this vehicle you repaired , but without seeing the cabling to the injectors, I would offer a guess that the injector wires are not shielded, are carried in a bundle & then "fanned out" to the individual injectors. I would further suggest that the high current to the shorted injector is inducing current pulses into the other injector wires, causing the affected injectors to have limited pulse height, and/or narrower pulse width. I would guess that the longer the engine idles, the lower the shorted injectors input resistance becomes & the higher the short circuit current becomes, exacerbating the problem. I offer this as a possible explanation for the multiple misses which disappear when the #1 injector cable is unplugged. Once again, I emphasize that I am NOT a mechanic, hold NO qualification as a mechanic ( the local single moms bring vehicles to me to fix because they can't afford to pay the outrageous rates shops charge ) but I lay a modest claim to understanding a bit about electrics & electronics.
    At 80 years of age when I am confronted with a perplexing electronic problem, I wistfully wish I was 16 again when I knew EVERYTHING . It is amazing how much my knowledge & understanding have diminished over the years. Sometimes I even ask for opinions from people who are smarter than I (a significant portion of the population). I love your videos Eric, & you have the best understanding of electrics & electronics in vehicles of any mechanic I have encountered. Keep up the good work & all the best to you & your family.

  10. Avataaar/Circle Created with python_avatars YH says:

    Great job Eric. Great video. I'm curious to know if any other misfire source malfunction (i.e. ignition coil) would have the same effect on the other cylinders, or is this problem unique to the fuel injector. It sounds like perhaps it could be an ECU software issue unique to that make/model car. I'm wondering if the ECU has the latest software update that may affect that issue. Just a thought.

  11. Avataaar/Circle Created with python_avatars Glenn Hamblin says:

    OMG Eric O is human!

  12. Avataaar/Circle Created with python_avatars Bob Johnson says:

    I'm going to apply for a job at SMA. I arrive before Mr. O., walk the lot, diagnose the cars, fill out work orders with "runs like poop", then let Mr. O do the rest. If he can do it, I can do it.

    Your skill level is truly amazing 🏆

  13. Avataaar/Circle Created with python_avatars RussianSokol - Daily Gaming Videos says:

    Part hanger would say need engine, and it would fix it, but way to expensive

  14. Avataaar/Circle Created with python_avatars bookerol says:

    I'm going to have to put my scope to work, from now on. That was very enlightening Eric.
    Recently had an Acura in the shop with all the cylinders throwing misfire codes. I didn't draw that job, but those involved assumed the INTERNET fix of valve adjustment, was the way to go… I doubted it, but if it returns, most likely it will come my way.

  15. Avataaar/Circle Created with python_avatars Larry Ehrlich says:

    So…is the moral of the story…slow is faster?

  16. Avataaar/Circle Created with python_avatars its jesusin says:

    i believe if you do a ecm pcm reset and start it after u can see what cylinder is misfiring.pcm going loco lol

  17. Avataaar/Circle Created with python_avatars C Cameron says:

    In a previous career, I was managing some on aircraft testing (it was a two day test). I had a well defined plan that should have worked. Near the end of day two, some of the crew was getting anxious to clean up. I let them convince me that they could start pulling some equipment unrelated to the test I was performing. All of the sudden my test went to sh!t. It turns out there was one connection that they pulled that they shouldn't have. I was pissed…. almost as pissed as the Major that scheduled two days of aircraft downtime for us to do the testing.

    Since then, I ALWAYS stick to my plan!! Some lessons come hard.

  18. Avataaar/Circle Created with python_avatars Torquing with Larry says:

    This is a funky Honda. They got lucky to have you to found the exact problem.

  19. Avataaar/Circle Created with python_avatars A J says:

    As a pilot we use checklists for everything. Even the for things we have done a zillion times we whip out the checklist and usually follow it line by line

  20. Avataaar/Circle Created with python_avatars Ishmael Patel says:

    This is how ya got to be good. Nothing like spitting on a car an goin to lunch to comeback and see your mistake laughing at yas

  21. Avataaar/Circle Created with python_avatars Dunc Keroo says:

    O2 sensor loop likely make other cylinders to rich to deal with unconsumed O2 — that's where your misfire counts come in.

  22. Avataaar/Circle Created with python_avatars Buff Barnaby says:

    I have a pro mechanic friend…then I go to pick-a-part and get the part it needs for a few dollars.

  23. Avataaar/Circle Created with python_avatars Robinson's Motorcycle and Auto Entertainment Zone says:

    Great job and so true about having a routine.

  24. Avataaar/Circle Created with python_avatars the driveway Man says:

    Problems like this make your channel worth watching

  25. Avataaar/Circle Created with python_avatars John Christopherson says:

    Eric, this is a S.W.A.G., but could the shorted injector cause the injector driver in the module to act up from increased amperage due to the shorted injector ? just wondering.

  26. Avataaar/Circle Created with python_avatars Willem Streutgers says:

    Eric, thanks for this lesson.

  27. Avataaar/Circle Created with python_avatars Moon Moon says:

    I haven't scoped my own car yet so I haven't learned. But I remember you saying something along the lines of a misfire is counted by checking the engine speed at a certain point in time, if the ECU is not what it expects it to be, it counts a misfire. Something along those lines. Generally injectors are driven from the ECU. So It's possible that the injector going short is pulling parts of the ECU low and is making the ECU go wonky? I dunno, this is pure speculation, there's a reason I'm not a mechanic.

  28. Avataaar/Circle Created with python_avatars Billy Smith says:

    Yep stuck to what you normally do. Works for me…….happens to us all

  29. Avataaar/Circle Created with python_avatars Dano C. says:

    Yes, Eric, after all, one of your mottos is "sometimes you need to slow down to go fast". Case and point…

  30. Avataaar/Circle Created with python_avatars ice44567 says:

    That's the weirdest thing I've ever seen. I wonder if the one injector being shorted was pulling down the current for the rest of them and causing them to not fire correctly? But that doesn't explain why their per firing amperage didn't go up after you disconnected #1, or at least I didn't see it go up. I'm curious as to what the fuel pressure was reading during these tests.

  31. Avataaar/Circle Created with python_avatars Dennis 2 says:

    I look forward to how you fixed it.

  32. Avataaar/Circle Created with python_avatars S & A Auto Repair says:

    Sometimes rabbit holes are disguised as diagnostic funnels and we let our smarts out smart us. Nice recovery

  33. Avataaar/Circle Created with python_avatars thehappyTexan says:

    Just a theory- it’s possible that a shorted injector would put too much demand on the injector driver in the ecm, which would then have increased resistance as it started to overheat from being overloaded. I saw that happen twice on Cummins engines about 7 years apart. You can bet your paycheck I remembered real quick the second time around that the computer isn’t always right. They would both misfire until you hooked up the laptop and did a cutout test. As soon as I clicked “start” on both trucks, the miss went away. Cummins said it’s because their t/s software actually forces the drivers to put out max power to all 6 injectors during the test.

  34. Avataaar/Circle Created with python_avatars Rob Buell says:

    Definately a strange one, if the ground is common to all 6 injectors the short could be affecting the firing of the other 5 when plugged in.

  35. Avataaar/Circle Created with python_avatars Christopher Arteaga says:

    Thank you for this video, it reminds us to stick to routine, other wise we go chasing other potential problems.

  36. Avataaar/Circle Created with python_avatars jr neff says:

    almost a pico only tool too fix this car your thoughts

  37. Avataaar/Circle Created with python_avatars Alasdair Munro says:

    Could the shorting injector be pulling the voltage lower for the other injectors, or if the feed to the injectors is current limited, current flowing preferentially in the shorted injector reduces that available to the others, and hence can’t open properly, causing misfires?

  38. Avataaar/Circle Created with python_avatars WykydWaze says:

    is it getting fire?
    is it getting fuel?
    is it getting air?

  39. Avataaar/Circle Created with python_avatars Antonio Claudio Michael says:

    I went down a few of these rabbit trails because I didnt do my normal procedure them days was working on a 2000 4runner with the 3.4l v6 and couldn't figure out why it was missing on 3 different cylinders found out that the timing was fine and the fuel was fine spark was fine but the number 1 cylinder coil was bad causing the other cylinders to not get there spark as well so thought it was spark plugs and these Toyota have 3 coils on passenger side and 3 wires on driver side 2 of the miss fires were on 1 coil because the coil runs one wire and the spark plug connected to the coil and the 3rd was a coil that was going bad if it would have been left longer would of been 4 cylinders missing out of 6 was frustrating to say the least 19 years on factory coils isn't bad though

  40. Avataaar/Circle Created with python_avatars Brian Mason says:

    That was great!!!!!

  41. Avataaar/Circle Created with python_avatars Antonio Claudio Michael says:

    Very interesting diagnostic find Eric O

  42. Avataaar/Circle Created with python_avatars Antonio Claudio Michael says:

    Never seen a injector 1 cause multiply miss fires on other cylinders interesting very interesting

  43. Avataaar/Circle Created with python_avatars Dave DiPetrillo says:

    When I was in my automotive electrical class we would have to diagnose bugs that the teachers would put into the car. One team got a headlamps inoperable on what I think was a Toyota Camry from the early to mid 2000’s. They spent a solid two days trying to figure it out. They checked fuses, current draw, continuity, everything and then some. Turns out that model has a weird switch that is kinda hidden away. It’s this little push button thing. All they had to do was hit the switch and the lights worked perfectly. That team was so pissed. I thought they were going to cry.