random misfire on cold start up 03 sts
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Cadillac Seville / Cadillac Eldorado Forum Discussion, random misfire on cold start up 03 sts in Past Cadillac Vehicle Discussion; It's seems I get a random miss fire on cold start up on cold days ,it usually happens for maybe ...
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    random misfire on cold start up 03 sts

    It's seems I get a random miss fire on cold start up on cold days ,it usually happens for maybe 20 seconds when first started where you can feel the misfire then it will smooth out and idle and drive fine.p0300 is the code, I went to advanced auto to see what cylinder was miss firing but the scanner they loaned out was the smaller cheaper one and it read out p0300 also.shouldn't the better scanner tell me what cylinders are misfiring? Also what direction should I be looking since it only happens on cold start up when it's cold out?

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    Submariner409's Avatar
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    Re: random misfire on cold start up 03 sts

    Might be something in this long thread .............

    http://www.cadillacforums.com/forums...n-takeoff.html

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    Re: random misfire on cold start up 03 sts

    shouldn't the better scanner tell me what cylinders are misfiring?
    Yes, and that would be the p[lace to start.

    Also what direction should I be looking since it only happens on cold start up when it's cold out?
    My guess would be a plug, boot or coil. I assume you are NOT using any coolant?

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    Yeah I'll go to another advanced to see if they have a better scanner, the only coolant that I'm loosing that I know of is the crossover leak.I forgot to mention there have been a couple of times it would misfire after warmed up when sitting at a light.it seems to drive/accelerate fine as of now.I'll try to get a better scanner.

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    I've been to five aap and none of them loan out the better scanners, all little ones.anyways this morning when I started her up it started misfiring to the point the ses light was flashing,I turned the car off then back on and it was fine and the ses light even went out .when I changed my plugs at 100,000 I didn't changed the boots, should of the boots been changed too?

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    Should the spark plug boots be changed at 100,000 miles when the plugs are done?

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    Yup, at least, i would

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    Do the plug boots need to be AC Delco like the plugs?

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    Re: random misfire on cold start up 03 sts

    Several options in RockAuto. ........... or talk to Chris in parts at Rippy Cadillac in Vendors or over there >>>>>>>>>>>

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    Yeah I was looking on rockauto I was just seeing is it important to use AC Delco boots like with the plugs or will any boot do?advanced auto doesn't carry AC Delco spark plug boots they have autolite,ngk or denso , would any of those brands do and if so which one or should I order the AC Delco boots from rock auto?

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    Re: random misfire on cold start up 03 sts

    Any of those boots should be just fine.

    Look at the ones you decide on - if the plug tip end does not already have a smear of dielectric grease in it, buy a small tube and use a toothpick to spread a tad of grease in the first 1/4" of each boot interior.

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    Thanks ,the correct plugs are AC Delco #41-987 right for 03 ?

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    Re: random misfire on cold start up 03 sts

    Yep - here you go - your ignition setup. 2000 - 2004 Northstar series. Go through my albums - The Community tab, Albums, the red Seville.

    NOTE: 2004 Deville may have the newer 4-coil and mounting rack arrangement. Not swappable.

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    Re: random misfire on cold start up 03 sts

    Quote Originally Posted by sts 03 View Post
    Do the plug boots need to be AC Delco like the plugs?
    Unless I am wrong, the boots are simply rubber insulators over a coil spring. It's the spring that makes the connection between the coil and the plug. Unless the boot is carbon tracked (unusual) I see no reason to replace them. I have yet to have a need to have mine off so I've not seen them up close and personal so I could be wrong.

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    the recluse is offline Cadillac Owners Connoisseur
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    Quote Originally Posted by Ranger View Post
    Unless I am wrong, the boots are simply rubber insulators over a coil spring. It's the spring that makes the connection between the coil and the plug. Unless the boot is carbon tracked (unusual) I see no reason to replace them. I have yet to have a need to have mine off so I've not seen them up close and personal so I could be wrong.
    You are right, they are just springs...however, I have seen these springs lose compression, corrode, or even break (from rusting up)...I have also seen the plug "cup" fill with oil when the gaskets go...

    If it just started happening when you changed the plugs, are you sure the caps on the plugs were screwed down all the way?

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