2001 Seville PCM P0300 Code
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Cadillac Seville / Cadillac Eldorado Forum Discussion, 2001 Seville PCM P0300 Code in Past Cadillac Vehicle Discussion; Ok, i have the P0300 code and no lean fuel codes. Ive pulled the intake apart and checked the Plenum ...
  1. #1
    Midianite is offline Cadillac Owners Member
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    2001 Seville PCM P0300 Code

    Ok, i have the P0300 code and no lean fuel codes. Ive pulled the intake apart and checked the Plenum boot, no tear or crack. The engine runs rough and i getting a red glowing Cat Converter. I was told the its not burning all the fuel to get the Cat hot like that. 87k miles on it not sure where to go from here. Seems like the Plenum Boot is the sure fix for this problem when i search the forums. Any help is much appreciated.

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  3. #2
    basscatt's Avatar
    basscatt is offline Cadillac Owners Master
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    Re: 2001 Seville PCM P0300 Code

    0300 is a generic misfire code -
    unfortunately - our on-board code reader does not tell us WHICH
    cylinder/cylinders are misfiring -

    go to AutoZone or any large auto parts store
    and have them read the codes for you -

    the misfire code 0301 is for cylinder #1 -
    0303 is cylinder #3 - 0305 is for cylinder #5 - etc -

    your cat glowing red tells me you are not burning all the fuel -
    my guess is probably a bad ignition coil -

    if you continue driving like this -
    you WILL be buying a new cat in addition to fixing the original problem -

  4. #3
    Ranger's Avatar
    Ranger is offline Cadillac Owners Member
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    Re: 2001 Seville PCM P0300 Code

    Check for a leaky FPR.

  5. #4
    Midianite is offline Cadillac Owners Member
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    Re: 2001 Seville PCM P0300 Code

    I have the car pulled apart right now, wanted to fix it b 4 i burnt out the Cat. Ive pulled the cassets and the boots and plugs. All the plugs looked bad, easily over .050 gap. Wondering if Autolite is the original plug that came with the 2001 sls. Will have to wait till tomorrow to get new plugs AC Delco right.. The boots dont look like much more then coiled wire housed in a boot, do they really need changed? Will check the FPR and the Ignition coil, and I'll post more when I know more. Thanx for the fast replies!

  6. #5
    Ranger's Avatar
    Ranger is offline Cadillac Owners Member
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    Re: 2001 Seville PCM P0300 Code

    NO! It did not come with Autolight plugs. It came with A/C Delco 41-987 plugs and that is what you should replace them with.

    No need to change the boots unless they are carbon arced or damaged.

    Wouldn't hurt to check the PCV hoses as well as all the other vacuum lines for tightness.

  7. #6
    Midianite is offline Cadillac Owners Member
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    Re: 2001 Seville PCM P0300 Code

    Just pulled the FPR and not sure if its bad or not, just looks like its been used per shape of the O rings. The boots look good still have electrical grease in them. I had checked the vacuum lines and the hoses before I started pulling everything apart. Im going to replace the FPR and the plugs tomorrow if I can get the parts after work. Thank you again for the quick reply!


    Also was told to replace the dle Air Control. will post after i get it all back together and list results.

  8. #7
    Submariner409's Avatar
    Submariner409 is offline If it won't run, stick on fender vents
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    Re: 2001 Seville PCM P0300 Code

    Instead of replacing a $200 IAC for no reason, remove it and clean the top hat and bore carefully, using throttlebody cleaner spray and lint-free rags.

    Your engine takes AC Delco #41-987 Platinum plugs only. Don't get creative. (If it wasn't you, a previous owner, tracking down an elusive miss, replaced the plugs with incorrect Autolites.) As posted, suspect a coil cassette. Junkyard. They're both the same - black or gray - and the 2 ICM's are the same part number. Make sure the ground spring is clean and "springy".

    Pictures of all this in my albums - click my username, open the profile. 2 albums, 6 pages of parts and diagrams for our engines and cars in the left column. (I see that you've already been there.........)

  9. #8
    Ranger's Avatar
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    Re: 2001 Seville PCM P0300 Code

    Quote Originally Posted by Midianite View Post
    Just pulled the FPR and not sure if its bad or not, just looks like its been used per shape of the O rings. The boots look good still have electrical grease in them. I had checked the vacuum lines and the hoses before I started pulling everything apart. Im going to replace the FPR and the plugs tomorrow if I can get the parts after work. Thank you again for the quick reply!
    No need to replace the FPR. Just pull the vacuum line at idle and look for fuel at the nipple. There should be none. If there is no sign of fuel there, it is good.

  10. #9
    Midianite is offline Cadillac Owners Member
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    Re: 2001 Seville PCM P0300 Code

    Autozone Just opened up here and was able to get the 41-987 plugs and gaskets for the plastic intake unit(?), the IAC and the FPR were not in stock, so i cleaned and replaced the old ones. There was no fuel in the vaccuum line from the FPR so i will avoid replacing that and said IAC. I did look up what a bad IAC does to the car and it starts fine and runs ok cold and in park/nuetral so I hadn't planned on replacing it. My coil cassettes looked good as far as i could tell, i checked the springs were making good contact and were clean whenIi reinstalled the cassettes. She ran good for about an hour, and was shut off for about 10 mins then when I started her back up she was back to rough idle and I didnt want to risk burning into the Cat Converter again. I will look into finding the Coil Cassette. Any way to troubleshoot which cassette or ICM could be giving me fits?

    The pics in your profile albums were very helpfull Submariner409. Thank you for the availability of them!

    Thank you both Ranger and Submariner409 for the replys and quick responses!

  11. #10
    CadillacSevilleSTS is offline Cadillac Owners Fanatic
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    This is one of the rare events that an external code reader is better than the onboard diagnostics since p0300 is a generic code for misfire and does not specify which cylinder is misfiring, but simply there is a misfire. Use an external reader and figure out which cylinder is misfiring. At that point you can easily see if the coil cassette is the problem and which to replace. For example if you get p0301 switch the cassettes and run the codes again. If the code changes to p0308 you know the cassette or icm is bad. At that point you can pinpoint if it is the cassette or ICM by switching the ICMs and seeing if the code switches again. If the ICM is bad let me know. I have one you can have.

  12. #11
    basscatt's Avatar
    basscatt is offline Cadillac Owners Master
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    Re: 2001 Seville PCM P0300 Code

    Quote Originally Posted by Midianite View Post
    Autozone Just opened up here and was able to get the 41-987 plugs and gaskets for the plastic intake unit(?), the IAC and the FPR were not in stock, so i cleaned and replaced the old ones. There was no fuel in the vaccuum line from the FPR so i will avoid replacing that and said IAC. I did look up what a bad IAC does to the car and it starts fine and runs ok cold and in park/nuetral so I hadn't planned on replacing it. My coil cassettes looked good as far as i could tell, i checked the springs were making good contact and were clean whenIi reinstalled the cassettes. She ran good for about an hour, and was shut off for about 10 mins then when I started her back up she was back to rough idle and I didnt want to risk burning into the Cat Converter again. I will look into finding the Coil Cassette. Any way to troubleshoot which cassette or ICM could be giving me fits?

    The pics in your profile albums were very helpfull Submariner409. Thank you for the availability of them!

    Thank you both Ranger and Submariner409 for the replys and quick responses!
    ---------------------------------
    Any way to troubleshoot which cassette or ICM could be giving me fits?
    read post #2

  13. #12
    CadillacSevilleSTS is offline Cadillac Owners Fanatic
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    Quote Originally Posted by basscatt

    ---------------------------------
    Any way to troubleshoot which cassette or ICM could be giving me fits?
    read post #2
    His question was which cassette or ICM. Post #2 will only tell him which cylinder. My method above will pinpoint in more detail.

  14. #13
    Midianite is offline Cadillac Owners Member
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    Re: 2001 Seville PCM P0300 Code

    Ive been messing with it on and off today, seems like it will be all right to get it down and tested at autozone if my store here can do that. Just didnt want to burn the Cat up per Basscatt's post #2. I did try to just disconnect it for the time being to get it tested/worked on somewhere but I am limited in ways to lift the car far enough to get thoes bolts loose. (no emissions laws here) Will take it down and do the process of elemination as per CadillacSevilleSTS's instructions.

    Thank you both for your posts in regards to my problem!

  15. #14
    Midianite is offline Cadillac Owners Member
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    Re: 2001 Seville PCM P0300 Code

    Autozone pulled cylinder #8 as the misfireing one, priced one out there at about $200, so I bought it. Its the wifes car and we dont own a spare automatic for her to drive. My truck is a manual. I just needed to get it fixed fast, but it worked, Ive taken it out about town and on the interstate, ran like a champ! I suppose i should have stopped at RiZzLe7's thread 2001 SLS misfire cylinder #8 but there was nothing on there about the Cat Converter heating up like mine was so I had thought I had a different problem.

    You all have my deepest thanks for your help with my repair, if not for this forum and everybody on here theres no way i could have done this as cheaply and easily as it was!

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