P 0300 Random/ multiple misfire detected - STS 97
Cadillac
 

Cadillac Forums | Help Us Help You | Advertise | Cadillac Parts | Cadillac News | Cadillac Classifieds / (Old System)

Cadillac Technical Archive | Cadillac Dealers | Cadillac Reviews | Cadillac Dealer Reviews | Cadillac Vendors

CadillacForums.com is the premier Cadillac Forum on the internet. Registered Users do not see the above ads.
+ Reply to Thread
Results 1 to 10 of 10
Cadillac Seville / Cadillac Eldorado Forum Discussion, P 0300 Random/ multiple misfire detected - STS 97 in Past Cadillac Vehicle Discussion; First my exhaust was broken for awhile and I still drove the car, about 3 months. I recently had a ...
  1. #1
    zek4964 is offline Cadillac Owners Fanatic
    Automobile(s): 08 cts 68k, 07 STS-V 15K, 97 Sts 160k
    Join Date
    Jun 2010
    Location
    Rochelle IL
    Posts
    302

    P 0300 Random/ multiple misfire detected - STS 97

    First my exhaust was broken for awhile and I still drove the car, about 3 months. I recently had a shop weld it up and it sounds great. Ever since the motor has been running rough, this has been going on for two weeks now and the first code just popped the po300. It seems that the misfire is when the car is first started but then goes away after a few miles, then only returns after siting for awhile. The plugs and wires have about 50k on them. Not sure if I should start there or what.

    Some more info is that I had a EGR recirculating flow low code set before the exhaust break, then it went away while the exhaust was broke, now the exhaust is fixed and no EGR code, but now the engine is running rough now with the p0300 code.

    Mass flow, plugs wires, catalytic converter, TB????????

  2. Remove Advertisements
    CadillacForums.com
    Advertisements
     

  3. #2
    ELDO GUY's Avatar
    ELDO GUY is offline Cadillac Owners Fanatic
    Automobile(s): 2K ELDO WHITE DIAM , 2K TURBO BUG ,69 VETTE ZZ4 2014 CTS
    Join Date
    Sep 2004
    Location
    SKOKIE ,iLL
    Age
    64
    Posts
    353
    Check the coils!

  4. #3
    Submariner409's Avatar
    Submariner409 is offline If it won't run, install a sound system
    Automobile(s): 2002.5 F55 STS/65500mi, 2004 Ford F150 SuperCab4x4
    Join Date
    Feb 2006
    Location
    MD Eastern Shore - Kent Island
    Age
    74
    Posts
    45,596

    Re: P 0300 Random/ multiple misfire detected - STS 97

    Plugs, wires, coils, ICM base contacts, ICM ground wire.

    Use this to make sure the plug wires are correctly connected to the coils and plugs.

  5. #4
    Ranger's Avatar
    Ranger is offline Cadillac Owners Member
    Automobile(s): White Diamond '03 DHS (with DTS floor shift)
    Join Date
    Jun 2004
    Location
    Woodstock Ill.
    Age
    66
    Posts
    74,555

    Re: P 0300 Random/ multiple misfire detected - STS 97

    When was the TB last cleaned?

  6. #5
    basscatt's Avatar
    basscatt is offline Cadillac Owners 10000+ Posts
    Automobile(s): 89 Coupe DeVille, 95 Sedan DeVille, 03 SLS, two 02 DHS's
    Join Date
    Feb 2004
    Location
    Minnesota
    Age
    63
    Posts
    10,356

    Re: P 0300 Random/ multiple misfire detected - STS 97

    P0300 is a generic misfire code -
    our on-board code readers will not display WHICH cylinder/cylinders is/are misfiring -
    only that there IS a misfire -

    take the car to any large auto parts store - they will check your codes for free -

    P0301 is a misfire in cylinder #1 - P0302 is cylinder #2 - P0303 is #3 - etc -

    once you discover WHICH cylinder is misfiring - diagnosis becomes much easier -

  7. #6
    zek4964 is offline Cadillac Owners Fanatic
    Automobile(s): 08 cts 68k, 07 STS-V 15K, 97 Sts 160k
    Join Date
    Jun 2010
    Location
    Rochelle IL
    Posts
    302
    Thread Starter
    Quote Originally Posted by Ranger
    When was the TB last cleaned?
    I cleaned it about 20k miles ago maybe more. I put 93 octane in it to flush out any bad gas that may be in it. The car misfires on the cold first start after that it runs fine.

  8. #7
    Ranger's Avatar
    Ranger is offline Cadillac Owners Member
    Automobile(s): White Diamond '03 DHS (with DTS floor shift)
    Join Date
    Jun 2004
    Location
    Woodstock Ill.
    Age
    66
    Posts
    74,555

    Re: P 0300 Random/ multiple misfire detected - STS 97

    What makes you think you had "bad gas"?

    The car misfires on the cold first start after that it runs fine.
    Hmm, are you by any chance using coolant?

  9. #8
    JimD is offline Cadillac Owners Connoisseur
    Automobile(s): '98 STS (RIP @ 206,xxx miles)
    Join Date
    Sep 2003
    Location
    Atlanta area
    Posts
    4,813

    Re: P 0300 Random/ multiple misfire detected - STS 97

    Quote Originally Posted by zek4964 View Post
    ....It seems that the misfire is when the car is first started but then goes away after a few miles, then only returns after siting for awhile. The plugs and wires have about 50k on them. Not sure if I should start there or what.
    A misfire at cold start can be one of the early symptoms of bad news.

    Are you having to add coolant to the system?

  10. #9
    zek4964 is offline Cadillac Owners Fanatic
    Automobile(s): 08 cts 68k, 07 STS-V 15K, 97 Sts 160k
    Join Date
    Jun 2010
    Location
    Rochelle IL
    Posts
    302
    Thread Starter
    I have not added coolant since I replaced the surge tank. I have been driving it to work and the temp gauge has not been above midway point since the surge tank change.
    What bad news are you talking about head gasket? I really hope not it will be a dead car because I will not fix it.

  11. #10
    Ranger's Avatar
    Ranger is offline Cadillac Owners Member
    Automobile(s): White Diamond '03 DHS (with DTS floor shift)
    Join Date
    Jun 2004
    Location
    Woodstock Ill.
    Age
    66
    Posts
    74,555

    Re: P 0300 Random/ multiple misfire detected - STS 97

    Quote Originally Posted by zek4964 View Post
    What bad news are you talking about head gasket?
    Yes, that's one of the early HG symptoms, but since you have not added coolant and the temp gauge has not moved I think you are OK.

Quick Reply Quick Reply

Register Now

Please enter the name by which you would like to log-in and be known on this site.
If you do not want to register, fill this field only and the name will be used as user name for your post.

Please enter a password for your user account. Note that passwords are case-sensitive.

Please enter a valid email address for yourself.

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Bookmarks

Cadillac Posting Rules

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
Read about Lincoln | Buick | Kia Forte Forum
Need products for your Cadillac? Check out your options at the links below:

custom floor mats | Cadillac Chrome and Black Chrome Wheels | window tinting