Idles rough after being started in the morning
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
Page 1 of 2 1 2 LastLast
Results 1 to 15 of 28
Northstar Engines and System Technical Discussion Discussion, Idles rough after being started in the morning in Cadillac Engine Technical Discussion; 1994 STC Over the Summer I have performed several repairs and general maintenance. Water pump replaced, spark plug wires, spark ...
  1. #1
    29Roadster is offline Cadillac Owners Member
    Automobile(s): 1994 Eldorado STC
    Join Date
    Dec 2008
    Location
    San Francisco Bay Area
    Age
    58
    Posts
    17

    Idles rough after being started in the morning

    1994 STC

    Over the Summer I have performed several repairs and general maintenance.
    Water pump replaced, spark plug wires, spark plugs, two ignition coils, coolant replaced, etc.

    All was running well, until recently when gradually over a couple of weeks time the engine began to run rough after being started in the morning or after setting for more than an hour. It smoothes out after 20 seconds and runs smooth afterwards. I have noticed gas mileage has slipped slightly.
    Any ideas

  2. Remove Advertisements
    CadillacForums.com
    Advertisements
     

  3. #2
    Submariner409's Avatar
    Submariner409 is offline If it won't run, stick on fender vents
    Automobile(s): 2002.5 F55 STS/65500mi, 2004 Ford F150 SuperCab4x4
    Join Date
    Feb 2006
    Location
    MD Eastern Shore - Kent Island
    Age
    75
    Posts
    45,995

    Re: Idles rough after being started in the morning

    What engine ?

    Two ignition coils replaced sounds like early Northstar.

    What wires, plugs, coils ?

    Do some searching for FPR - Fuel Pressure Regulator - for just those symptoms.

  4. #3
    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
    74,815

    Re: Idles rough after being started in the morning

    Coolant levels and temperatures holding constant?

  5. #4
    29Roadster is offline Cadillac Owners Member
    Automobile(s): 1994 Eldorado STC
    Join Date
    Dec 2008
    Location
    San Francisco Bay Area
    Age
    58
    Posts
    17
    Thread Starter

    Re: Idles rough after being started in the morning

    Temp appears to be holding (198-207) and with the help of a small ruler to check the level it appears to have lowered a little over a 1/4" over the past week or so. But I was losing coolant before the current rough idle appeared.

  6. #5
    V-Eight's Avatar
    V-Eight is offline Cadillac Owners Connoisseur
    Automobile(s): 1991 Sedan Deville
    Join Date
    Mar 2009
    Location
    Winnipeg, MB
    Age
    23
    Posts
    2,937

    Re: Idles rough after being started in the morning

    Has it been getting cold in the morning?

  7. #6
    29Roadster is offline Cadillac Owners Member
    Automobile(s): 1994 Eldorado STC
    Join Date
    Dec 2008
    Location
    San Francisco Bay Area
    Age
    58
    Posts
    17
    Thread Starter

    Re: Idles rough after being started in the morning

    Temps have been in the low 60's at night and low 70's during the day. Perfect really.

  8. #7
    V-Eight's Avatar
    V-Eight is offline Cadillac Owners Connoisseur
    Automobile(s): 1991 Sedan Deville
    Join Date
    Mar 2009
    Location
    Winnipeg, MB
    Age
    23
    Posts
    2,937

    Re: Idles rough after being started in the morning

    Ok I was gonna say, if it was getting below 0 at night...not sure what that is in F, it could have just needed to warm up. I know my car runs rough for a few mins until it warms up in the winter.

  9. #8
    29Roadster is offline Cadillac Owners Member
    Automobile(s): 1994 Eldorado STC
    Join Date
    Dec 2008
    Location
    San Francisco Bay Area
    Age
    58
    Posts
    17
    Thread Starter

    Re: Idles rough after being started in the morning

    Quote Originally Posted by V-Eight View Post
    was getting below 0 at night...not sure what that is in F, it could have just needed to warm up.
    That would be 32F and it never gets that cold here, I'm in the San Francisco area. No it idles rough for a short time, then smooths out. I'm guessing it may be either something to do with a censor or in the fuel system. But I'm just guessing.

  10. #9
    29Roadster is offline Cadillac Owners Member
    Automobile(s): 1994 Eldorado STC
    Join Date
    Dec 2008
    Location
    San Francisco Bay Area
    Age
    58
    Posts
    17
    Thread Starter

    Re: Idles rough after being started in the morning

    New info

    I just took the Eldorado out to run a short errand; I noticed that at 45 mph the tach displayed 2000 rpm in overdrive. Then on the way back the tachometer showed the engine running at 3100 rpm while running at 45 mph (72kph)! I got home and parked the car.

  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
    74,815

    Re: Idles rough after being started in the morning

    Keep a close watch on the coolant level. Rough idle at start up and coolant usage are initial head gasket symptoms.

  12. #11
    29Roadster is offline Cadillac Owners Member
    Automobile(s): 1994 Eldorado STC
    Join Date
    Dec 2008
    Location
    San Francisco Bay Area
    Age
    58
    Posts
    17
    Thread Starter

    Re: Idles rough after being started in the morning

    Any ideas on teh high rpm?
    Trans?

  13. #12
    Krashed989's Avatar
    Krashed989 is offline Cadillac Owners Connoisseur
    Automobile(s): 94 Eldorado, and a 99 ETC
    Join Date
    Sep 2004
    Location
    Hilo, Hawaii
    Age
    27
    Posts
    3,887

    Re: Idles rough after being started in the morning

    High rpm at that speed sounds like your TCC (Torque Converter Clutch) failed to engage. That would usually throw a code. Check the codes by pressing and holding the OFF and warmer (red) buttons at the same time until the whole dashboard lights up (key in the "on" position with or without the engine running). It will then tell you the codes and finish with "PCM?" At that point you can either press the OFF button once again to have it repeat the codes or you can turn the key off to exit diagnostics mode. Post your codes up here and we will help you.

  14. #13
    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
    74,815

    Re: Idles rough after being started in the morning

    TCC would only raise the RPM by about 200. Not sure what is causing that kind of an RPM increase.

  15. #14
    Submariner409's Avatar
    Submariner409 is offline If it won't run, stick on fender vents
    Automobile(s): 2002.5 F55 STS/65500mi, 2004 Ford F150 SuperCab4x4
    Join Date
    Feb 2006
    Location
    MD Eastern Shore - Kent Island
    Age
    75
    Posts
    45,995

    Re: Idles rough after being started in the morning

    Those 45 mph engine speeds look like both a 4th gear engagement/TCC issue.

    The TCC rpm drop upon engagement/disengagement (brake tap) is on the order of 300 rpm +/-.

    4th is one pressure control, TCC is the solenoid, and the 1-2 and 2-3 shifts are a different set of solenoids.

  16. #15
    eyekandyboats.inc's Avatar
    eyekandyboats.inc is offline Cadillac Owners Connoisseur
    Automobile(s): 2001 DTS(140K), 2000 ETC(284K), 1990 allante( 80K)
    Join Date
    Mar 2007
    Location
    Tottenham, Ontario,Canada
    Posts
    1,914

    Re: Idles rough after being started in the morning

    hey sub i got a question semi related to the TCC.
    before my TCC went out at 130 Km/h ( 81 mph i think) the rpm was at 2600 or so.
    now that my TCC is gone and i see the slippage. i only see the slippage from any where from 80-120 after that or so. my rpm at 130 km/h is exactly the same!! so i was wondering does the tcc disengauge after a certain speed?

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