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Thread: Rough, miss-like idle

  1. #16
    Join Date
    Feb 2016
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    Cincinnati, OH
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    Well, that's definitely a possible issue on the DIS part. I put thermal paste on the mounting surface, thinking like its a computer part or heatsink. I'll clean it up tomorrow and retry. Though as long as i've had the car, i've never had an issue before... The previous owner did the same thing. This isn't the first time i've replaced the DIS(chasing a bouncing rpm needle).
    Matthew "Dale" Johnson
    ~"If it looks dumb and works, it's not dumb"

  2. #17
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    I meant bare metal where that large accessory bracket attaches to the front of the engine.

    The DIS -does- need the silicone paste that comes with it in the box. Just like this: https://www.autozone.com/miscellaneo...-sink-compound

    As long you used the grease that the DIS module came with then you're ok...leave it alone. The DIS module grounds thru it's corner bolts (and it wouldn't hurt for the metal it sits on to not be painted too).

    There are tests you can make to confirm the ground path is ok if it comes to that. You can also add temporary grounds to test. If the engine or those brackets haven't been painted then you should be ok and you just need to focus on the ground cables in general (what we call low hanging fruit), and at least the front harness specifically.
    Last edited by KMT; 02-18-2019 at 01:10 AM. Reason: Added link

  3. #18
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    Apr 2002
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    St. Charles, MO
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    Quote Originally Posted by Matt_aka_Dale View Post
    Yeah, not trying to just hang parts on it, just suck at diagnosing.

    -I have not re-checked for codes(have not bought a scanner)

    -was going to check plugs when replacing wires

    -I have an in-car fuel gauge that is quite reliable

    -no fuel in the vacuum line off the regulator

    -there hasn't been any major work to recently. Mid last year was when work was done.

    -I have no idea how many miles are on the injectors. They are 38lb's and the car has about 104,000miles on it with 12,000 on the engine.

    -some mods to the engine. Stage 1 cam, long headers, underdrive pulleys, a/c delete, EGR delete, ported 89 SC w/ 10% pulley and raised top, and a double IC.

    -O2's were replaced mid last year with the other work done.
    What type of tuning or chip are you using ? Asking because it would run pretty crappy on stock tune with long tubes and 38# injectors.

    David
    1991 SC AOD 4.2..2.3 Whipple..........10.910 @ 125.61
    2016 SRT Challenger Hellcat.............10.597 @ 135.78

    My Garage

  4. #19
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    Feb 2016
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    Cincinnati, OH
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    I guess it's a basic chip from supercoupesunlimited. Once again, it did fine before, so this time I really messed something up.
    Matthew "Dale" Johnson
    ~"If it looks dumb and works, it's not dumb"

  5. #20
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    Apr 2002
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    St. Charles, MO
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    Need to get codes ran again and post the numbers here. Should be 3 digit codes.

    You can pick up a code reader like this on Amazon, Ebay or at pretty much any auto parts store for around $30

    https://www.amazon.com/Actron-CP9015.../dp/B0006V2BGY

    David
    1991 SC AOD 4.2..2.3 Whipple..........10.910 @ 125.61
    2016 SRT Challenger Hellcat.............10.597 @ 135.78

    My Garage

  6. #21
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    Feb 2016
    Location
    Cincinnati, OH
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    Can electronic contact cleaner eat copper rtv? Saw someone else using it on here to check for vacuum leaks. I sprayed the IC piping then checked other places, and a few minutes later, the joint to the upper intake plenum started leaking.

    I do have a code reader now, but only get 2 digit codes.
    Matthew "Dale" Johnson
    ~"If it looks dumb and works, it's not dumb"

  7. #22
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    Location
    Salem OR
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    Can electronic contact cleaner eat copper rtv? Saw someone else using it on here to check for vacuum leaks. I sprayed the IC piping then checked other places, and a few minutes later, the joint to the upper intake plenum started leaking.
    Copper RTV spec sheet says this about that:

    "Chemical / Solvent Resistance
    The product retains effective properties in contact with most shop fluids, automotive fluids, such as motor oil, transmission fluids, alcohol and antifreeze solutions. Note: Not recommended for parts in contact with gasoline."

    If the joint was tight to begin with, it should be hard to get -anything- in there, so...

    I'd be wary of spraying anything to check for leaks. Small ones the computer will correct faster than you can notice them...big leaks tend to stand out on their own. A smoke test finds them all. You can rent a smoke machine from your local partysRUs, but hey...whatever works.

    I do have a code reader now, but only get 2 digit codes.
    I think 3-digit codes are found w/late model, but you have a chip/tune, so...

    My opinion at this point is you have a combination of vacuum leaks and electrical issues. I'd go after vacuum leaks first. Just remember that vacuum leaks are unlikely to throw CID errors.

  8. #23
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    Messing with the stock IC piping is getting old. I really need a fmic setup, just can't find any upper intake plenums made for it.
    Matthew "Dale" Johnson
    ~"If it looks dumb and works, it's not dumb"

  9. #24
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    Quote Originally Posted by KMT View Post
    Copper RTV spec sheet says this about that:

    "Chemical / Solvent Resistance
    The product retains effective properties in contact with most shop fluids, automotive fluids, such as motor oil, transmission fluids, alcohol and antifreeze solutions. Note: Not recommended for parts in contact with gasoline."

    If the joint was tight to begin with, it should be hard to get -anything- in there, so...

    I'd be wary of spraying anything to check for leaks. Small ones the computer will correct faster than you can notice them...big leaks tend to stand out on their own. A smoke test finds them all. You can rent a smoke machine from your local partysRUs, but hey...whatever works.



    I think 3-digit codes are found w/late model, but you have a chip/tune, so...

    My opinion at this point is you have a combination of vacuum leaks and electrical issues. I'd go after vacuum leaks first. Just remember that vacuum leaks are unlikely to throw CID errors.
    I get 3 digit codes on my 91 SC. I have several memorized like 214 for cam sensor.

    David
    1991 SC AOD 4.2..2.3 Whipple..........10.910 @ 125.61
    2016 SRT Challenger Hellcat.............10.597 @ 135.78

    My Garage

  10. #25
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    Salem OR
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    Quote Originally Posted by David Neibert View Post
    I get 3 digit codes on my 91 SC.
    Noted, thanks. Is your '91 OBD-I or OBD-II?

    I've only seen 2-digit so far on my '90 w/OBD-I, and matt has an '89.

    Ken
    Last edited by KMT; 02-19-2019 at 11:47 AM.

  11. #26
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    Quote Originally Posted by KMT View Post
    Noted, thanks. Is your '91 OBD-I or OBD-II?

    I've only seen 2-digit so far on my '90 w/OBD-I, and matt has an '89.

    Ken
    Ken,

    Yes it's OBD-1, must be different than the 89-90.

    David
    1991 SC AOD 4.2..2.3 Whipple..........10.910 @ 125.61
    2016 SRT Challenger Hellcat.............10.597 @ 135.78

    My Garage

  12. #27
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    Salem OR
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    Quote Originally Posted by David Neibert View Post
    ...must be different than the 89-90.
    David:

    I always assumed 3-digit codes were OBD-II centric, but according to this page, they are '91 (some) and up: http://www.thorssell.net/hbook/3digit.html

    Interesting.

    Ken

  13. #28
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    Quote Originally Posted by KMT View Post
    David:

    I always assumed 3-digit codes were OBD-II centric, but according to this page, they are '91 (some) and up: http://www.thorssell.net/hbook/3digit.html

    Interesting.

    Ken
    Yes, those are the same code numbers I get.

    David
    1991 SC AOD 4.2..2.3 Whipple..........10.910 @ 125.61
    2016 SRT Challenger Hellcat.............10.597 @ 135.78

    My Garage

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