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Thread: Cant find my misfire

  1. #1
    Join Date
    Jan 2012
    Location
    Anacoco, La
    Posts
    433

    Cant find my misfire

    Problem started if im running cruse control, when i go down hill and decelerate the converter unlock, no codes, but if i force clear computer it locks back up instantly. So i go to the trans shop. They said trans is in great shape everything is right, but have 2 cylinders misfireing and low volt on mass air meter, i replace the mass air meter, new injectors, msd coil packs, and a set of taylor plug wires, if im in park and hold the motor at 2500rpm for a min, light comes on for p0300. What can it be? Gonna change plugs today, but there only couple months old.

  2. #2
    Join Date
    Jan 2012
    Location
    Anacoco, La
    Posts
    433
    Fixed it, was a combanation of things, i knew i had an injector messing up, all the ignition parts was off my old motor so they had 173000 miles on em. So it didn hurt my feelings to change them. New injectors, coil packs, plug wires. But still couldnt find my misfire. Swaped plugs with some ngks and its fixed, my old plugs wasnt 3 months old but i guess bad injectors and weak coil packs killed them.

  3. #3
    Join Date
    Mar 2003
    Location
    San Antonio, TX
    Posts
    11,038
    or carbon tracking or a tiny crack in the plug.

  4. #4
    Join Date
    Feb 2009
    Location
    NC
    Posts
    104
    Glad you found the problem.
    I'm having an issue with mine, I have multiple misfires. When it locks up at cruising speeds I get a TC shudder. Only when it locks and when I stay at a consistent speed it will shudder after roughly 46mph it will stop.
    When its cold the shudder is bad, when its warm out, its almost like there's nothing wrong. Its very weird.
    Mine is an 07 Tahoe with DOD. I'm going to replace everything you had and also in the near future delete my DOD all together.
    I did replace my plugs and wires. I'd hate to have to do my plugs again after spending so much for the Delcos but, looks like I may have to do after reading about yours.

  5. #5
    Join Date
    Jan 2012
    Location
    DFW, TEXAS
    Posts
    594
    throwing parts at it always works. I hope you guys are not mechanics

  6. #6
    [QUOTElist.star;522994]throwing parts at it always works. I hope you guys are not mechanics[/QUOTE]

    What would you do in this scenario? They've been systematically checking each component Down the list.

  7. #7
    Join Date
    Feb 2009
    Location
    NC
    Posts
    104
    Quote Originally Posted by blacstar View Post
    throwing parts at it always works. I hope you guys are not mechanics
    You are obviously more experienced and have the right contacts.

    Me, not only am I new to the state, I don't know anyone. I have gone with mechanics who were recommended by people I work with or from google.
    Every mechanic I have talked to or made appointments with have come up empty handed and come up with two responses 1. no codes no problems 2. replace the converter.
    This is after about 10 hours worth of appointments and my time completely wasted.
    It seems that I have moved to a place that is lacking competent mechanics.

  8. #8
    Join Date
    Jan 2012
    Location
    DFW, TEXAS
    Posts
    594
    think about what is happening and all the possible causes. intake, compression, ignition, fuel. 4 stroke cycle. go down that list and you will always find the culprit.
    im not there in the flesh; therefore I don't know if you are going thru the check list correctly. example:there is dry compression and wet compression... what is the difference?
    don't take my words as me being a smartass... read the spark plugs. swap components from a good cylinder and write down the difference.
    move spark plugs, move injectors, move coils, noid light, check resistance in coils.

  9. #9
    Join Date
    Feb 2009
    Location
    NC
    Posts
    104
    There is certainly a lot more involved with my 07 than my previous 99. Everything is electronic. I did my plugs and wires because of the miles and thought it would help with the miss. What I am confused about is if I have a miss in all cylinders. This is why I have been in search for a capable mechanic with a scan tool to see if he can help me pinpoint where the misses is coming from. Is that the order I should check? Intake, compression, ignition and fuel? I have read about intake, ignition and fuel but have not seen about compression.
    By no means do I take what you are saying as being a smartass. It has been a very rough road the past few months and I have spent more than I would like to admit. My funds are running low and being in a new place does not help one bit.
    If you are referring to a compression test. I had recently done a compression test on my old AE86, both wet and dry. It determines more or less if you're going to need rings or if its going to be on the valve side.
    With having a miss in all cylinders. How is it possible for me to move each item around and see what's wrong when supposedly they are all out of wack?
    I have not seen a noid light. I'll have to see if my local auto shop carries them. What kind of meter would I need to check the coils?
    Thanks, I appreciate the assistance.

  10. #10
    Join Date
    Jan 2012
    Location
    DFW, TEXAS
    Posts
    594
    in terms of the compression test; that is verifying the mechanical side of the engine in relation the other cylinders. rings, headgasket, head, valves, etc.
    I have had my fluke volt meter for 10+ years.
    summit racing has noid lights from $5 for a single to 14 or 15 for a kit.
    im trying to help but its kinda hard

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