Rough running

Discussion in 'Frequently Asked Questions' started by grmpyoman, Oct 19, 2015.

  1. grmpyoman

    grmpyoman New Member

    Messages:
    11
    Likes Received:
    0
    Joined:
    Mar 14, 2015
    Location:
    Phoenix
    Hey everyone.
    I'm driving a 03 with 3.7. 180.000 miles. This thing is running really bad. Codes are 300 301 302 303 304. I know what they mean.
    But whenever the weather is cooler it runs ALMOST perfect.
    High idle on startup.
    Any thoughts...
     
  2. renegade 04

    renegade 04 Full Access Member

    Messages:
    1,443
    Likes Received:
    3
    Joined:
    Jan 3, 2014
    Location:
    Albany New York
    Sounds like bad spark plugs!
     
  3. ouroboros

    ouroboros Full Access Member

    Messages:
    315
    Likes Received:
    0
    Joined:
    Jun 27, 2015
    Location:
    Montrose, MI
    Tune up time. I bought mine with 114,xxx and it needed plugs badly, I got ambitious and did all 6 coils with all the plugs as well. The electrodes on the plugs were practically fried off. I stick with copper core only plugs, from my understanding that's what these motors like.
     
  4. nullptr

    nullptr Full Access Member

    Messages:
    344
    Likes Received:
    0
    Joined:
    Jan 18, 2015
    Location:
    Port Orange, FL
    Yep, those are misfire codes... for lots of cylinders. Change the plugs to start out with since those are cheap and probably need it anyway, make sure they are gapped correctly. :)
     
  5. ouroboros

    ouroboros Full Access Member

    Messages:
    315
    Likes Received:
    0
    Joined:
    Jun 27, 2015
    Location:
    Montrose, MI
    If you pop the hood there will be a placard or two that state the proper plug gap. NGK R plugs are what I use and what the manufacturer recommends.
     
  6. grmpyoman

    grmpyoman New Member

    Messages:
    11
    Likes Received:
    0
    Joined:
    Mar 14, 2015
    Location:
    Phoenix
    Got under the hood, pulled the coils and plugs on 1 3 5, plugs looked brand new, gapped correctly. Switched the coils 3 to 5 and 5 to 3.
    Disconnected batt to clear codes, about 20 min. Started It up, ran beautifully for a day and a half. Then started misbehaving again, codes same but didn't bring up cyl 2. Could this be the ECU?
     
  7. uss2defiant

    uss2defiant Full Access Member

    Messages:
    3,354
    Likes Received:
    35
    Joined:
    Jun 25, 2014
    Location:
    Tucson, Arizona
    switch ignition coil #4 to #5 or #6.
    see whether you get 305/6 instead of 304.
    If so then your coils are bad.
     
  8. mase

    mase New Member

    Messages:
    2
    Likes Received:
    0
    Joined:
    Oct 23, 2015
    Location:
    Seattle, wa
    You said the plugs looked new..Spend the $5 per new NGK plugs and replace them first. NG K OEM plugs work the best and gap correctly per under hood.
     
  9. grmpyoman

    grmpyoman New Member

    Messages:
    11
    Likes Received:
    0
    Joined:
    Mar 14, 2015
    Location:
    Phoenix
    Maybe I'm missing something here. But my question is why when I disconnect the battery, does it run perfectly for a day and a half, then start running badly again.
     
  10. tinyejp

    tinyejp New Member

    Messages:
    11
    Likes Received:
    0
    Joined:
    Oct 14, 2015
    Location:
    Chicora, PA
    Could be a sensor on it's way out. Crank sensor, TPS?
     
  11. JasonJ

    JasonJ Full Access Member

    Messages:
    1,521
    Likes Received:
    43
    Joined:
    Jul 8, 2013
    Location:
    Michigan
    Disconnecting the battery does not "clear the codes". You must do that with a code scanner, or the problem must be corrected and remain so for a large number of key cycles.

    Otherwise the codes are left as Pending. Just because the check engine light goes out, does not indicate that the codes are cleared.

    It will run differently after disconnecting the battery for a short while until the ECM relearns basic settings and drivability parameters as well. In all likelihood you may have a sensor of some sort going bad, a sensor whos inputs are listened to very much until the ECM starts running off of a re-learned mapping.

    However I too suspect possibly faulty coils. I'd throw new plugs in there (do you know how many miles or years are on them now?) and be prepared to buy new coils for each cylinder that had misfire code set. Looks like cyls 1, 2, 3 and 4. Also check for damaged vacuum lines and torn or cracked intake tube.
     
  12. grmpyoman

    grmpyoman New Member

    Messages:
    11
    Likes Received:
    0
    Joined:
    Mar 14, 2015
    Location:
    Phoenix
    Ok. I hope this helps someone out there, we've got this thing figured out. Cheap gas. These engines will not operate on cheap gas. It's got to be 91 octane . My buddy told me about this, I went and added some octane booster to what was already in the tank, and topped it off with 91 octane, and it is running beautiful now.
     
  13. grmpyoman

    grmpyoman New Member

    Messages:
    11
    Likes Received:
    0
    Joined:
    Mar 14, 2015
    Location:
    Phoenix
    Okay, we got this thing figured out. With the help of a good mechanic that I know he told me these engines will not run on low octane fuel. It was acting up again and he told me to put good 91 octane fuel in it, after I did with a little bit of octane booster, it is running beautiful.
     
  14. JasonJ

    JasonJ Full Access Member

    Messages:
    1,521
    Likes Received:
    43
    Joined:
    Jul 8, 2013
    Location:
    Michigan

    That's not true.

    I'm glad it fixes your problem, but as a general blanket statement about the 3.7 (and consequently the 4.7 v8), this is false. Most people do not even know what octane does and what the rating means.

    That's not to say that they run well on cheap gas, but cheap gas is different than saying "the cheapest gas option at the pump". The only difference between 87 and 91 octane in most stations, is LITERALLY the amount of octane (C8H18) added to reduce spark knock and pre-ignition. There is no quality difference.

    Now, if we're talking about top tier gasolines from higher quality refineries... as opposed to Admiral or no-name brand gas pumps..... that's different.

    Since your KJ runs better on higher octane fuel, you likely have high amounts of carbon buildup in the combustion chamber that is interfering with the proper engine cycle, possibly burning the fuel/air mix before the spark plug is meant to do so, that leads to misfires.

    Only about almost all of us run 87 octane every single day of the year without issue... so I'd just be cautious about generalized statements painted with broad strokes.

    But it's good you found a solution.
     
  15. Leeann

    Leeann Full Access Member

    Messages:
    2,331
    Likes Received:
    98
    Joined:
    Mar 9, 2013
    Location:
    Maryland
    If you have to add octane booster to 87 octane to make it run right, the cheap gas you've been buying isn't actually 87 octane.

    I don't know about Arizona, but the state actually tests the fuel here in MD - every year. If you're caught selling gas below the rating on the pump, it's a pretty hefty fine.
     
  16. JayPoecy

    JayPoecy New Member

    Messages:
    1
    Likes Received:
    0
    Joined:
    Mar 10, 2020
    hey guys,

    so the story is a local dealership had this ski for sale. it had 11 hours on it and last tag was 2017. it was a killer price that i couldnt pass up. picked it up on friday and took it to the lake to take it off the trailer to adjust my bunks so it would sit better. they fired it up for me at the dealership for a few seconds, ran great. took it to the lake, started it up in the water, ran great to reverse it off of the trailer and park it on the dock. pulled out of the water and thought that i would just take it on a 5-10 minute cruise for the hell of it. took it out, ran great at low rpms for a little bit big no wake zone. got past the no wake zone and eased on the throttle to go about 25-30mph for a few. still running great. then i gave it more throttle, got up to about 45 and it started to sputter and vibrate. turned around to where i was and the whole time it is running rough/sputtering/not wanting to rev/etc.. also, i put it in sport mode and tried to punch it and it sputtered, revved great for a second, then sputtered again. its just running rough. seeming to feel like it is misfiring. no check engine light, no overheating issue, nothing in the prop area.

    anyone have any insight before i talk to the dealer about it? i like fixing my own stuff rather than have someone else do it. just not sure if there is a common issue or anything. any help would be greatly appreciated