rough at idle only, but no check engine light
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Cadillac CTS First Generation Forum - 2003 - 2007 Discussion, rough at idle only, but no check engine light in Cadillac CTS Coupe, Sport Sedan and Sport Wagon Forums; hi all, i just bought my first caddy, a 03 cts, and im having a few problems already. in my ...
  1. #1
    joshk is offline Cadillac Owners Member
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    rough at idle only, but no check engine light

    hi all, i just bought my first caddy, a 03 cts, and im having a few problems already.

    in my excitement of buying a used car i think i may have overlooked this rough idle and now im at a loss of what it could be. i know there are alot of post attributing it to this or that but somehow they dont seem to apply to me, so sorry if this is a common topic.

    i just changed the air filter and cleaned out the throttle body and neither seemed to do much. i am currently waiting for the engine to cool a bit more before i tackle the plugs but untill then i though i would ask other owners.

    the roughness of the engine is felt more then heard, its like a looping feeling if that makes sense, like it kinda wants to die out but hasnt yet. the rpms do not seem to fluctuate but stay at about 600. when you get to about 1000 the engine smooths out like a baby butt. i am at a loss, if anyone has any tips or tricks let me know, i plan on bringing it to the dealer on tues but really rather not spend alot of money already, but if i have to i will to keep the caddy running like it should.

    thanks in advanced.

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  3. #2
    LouisI's Avatar
    LouisI is offline Cadillac Owners Member
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    Re: rough at idle only, but no check engine light

    I began having the same issue a while back and have still yet to figure out the problem. I also had the throttle body cleaned and the spark plugs changed and it did nothing. My mechanic told me it could possibly be a leak in a hose that could be causing the issue. I had the manifold gasket replaced and the spark plug coils as there was oil in three of my spark plug enclosures or basins, forgive my mechanic terminology ignorance. Mine also had a weird shift in between 3rd and 4th gear I believe. I'm sure someone with more knowledge will chime in, I am very curious myself and have unfortunately just had some more issues present themselves. Good luck.

  4. #3
    joshk is offline Cadillac Owners Member
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    Re: rough at idle only, but no check engine light

    ok so good lord getting to and taking off the coil packs is a pain. i got the drivers side done and what i uncovered is the drivers side rear plug was covered in oil. still working on the other side as there is even more stuff in the way, i will respond with the findings on that side as soon as i can. so any ideas now that i have some new information?

  5. #4
    DavidBoren's Avatar
    DavidBoren is offline Cadillac Owners Enthusiast
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    Re: rough at idle only, but no check engine light

    First start/cold engine, it usually revs up to 1,000rpms... even at idle. Once the engine warms up, gets to operating temp, the idle should calm down to 600rpms.

    Open your hood, leave engine idling, and listen to it from outside the car. Does it sound like what you think a Cadillac should sound like? Your '03 cars are different from the LY7 in 2005, otherwise I would say to service your timing chain. Either way, check your oil. Add as necessary.

  6. #5
    concorso is offline Cadillac Owners Master
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    Re: rough at idle only, but no check engine light

    There was a TSB for the 03's that raised the idle rpms to approximately 750 rpm to combat this issue.

  7. #6
    joshk is offline Cadillac Owners Member
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    Re: rough at idle only, but no check engine light

    ok so i finally finished the passenger side, whoever designed that bracket should be shot. anyways the back 2 plugs on the passenger side had oil, but not as bad as the driver back one did. i changed them all out and i cant say i notice much if any difference. for a second or 2 i though it smoothed out but that could have just been the car idling at 1000 but once it went to 600 it got rough again.

    i know someone said there is/was a tsb for the idle, would that be a free fix that the dealer would do or is it going to cost me because it was a while ago?

    as far as how it sounds, yea i guess oddly enough it does sound ok, especially for a 10 year old car (although it only has 88000 miles) it just feels rough when you touch it or sit inside.

  8. #7
    concorso is offline Cadillac Owners Master
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    Re: rough at idle only, but no check engine light

    Im not sure about how TSBs are treated outside of warranty. If you had to pay for it yourself, Id guess it would be about 70 bucks, or 1/2 hour of labor at the dealer. They would simply hook up a TechII, adjust the idle rpms, and then give the car back. That actual work is about 5 minutes.

  9. #8
    joshk is offline Cadillac Owners Member
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    Re: rough at idle only, but no check engine light

    if thats all it is then im a happy guy.

    but that still doesnt explain the oil covering 3 of the spark plugs, im not sure what to look for to see if they have done the pvc valve job or not, but i suppose the dealer will let me know.

    also im just curious if i got a good deal to begin with, it has 88000 on the 03, body is in good condition, no rust just some pings. and with the obvious oil and rough idle otherwise everything seems perfect. i paid 6900. so did i get a deal? or get ripped off a bit?

  10. #9
    arogers260's Avatar
    arogers260 is offline Cadillac Owners Enthusiast
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    Re: rough at idle only, but no check engine light

    This is what the pcv update looks like


    If you have this oil filler cap and cover on top of the plenum then you have the updated pcv otherwise it hasn't been done yet.

  11. #10
    arogers260's Avatar
    arogers260 is offline Cadillac Owners Enthusiast
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    Quote Originally Posted by joshk View Post
    if thats all it is then im a happy guy.

    but that still doesnt explain the oil covering 3 of the spark plugs, im not sure what to look for to see if they have done the pvc valve job or not, but i suppose the dealer will let me know.

    also im just curious if i got a good deal to begin with, it has 88000 on the 03, body is in good condition, no rust just some pings. and with the obvious oil and rough idle otherwise everything seems perfect. i paid 6900. so did i get a deal? or get ripped off a bit?
    I'd say you got a pretty good deal at 6900. Mine is blue booking a little under 6900 with 144000 miles

  12. #11
    joshk is offline Cadillac Owners Member
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    Re: rough at idle only, but no check engine light

    hmmmm mine doesnt look exactly the same. do the update parts always look like the pictures above or could mine just be different? if i dont have the kit how much does it usually cost with and without install?

    IMAG0141resize.jpg

    IMAG0140resize.jpg

  13. #12
    arogers260's Avatar
    arogers260 is offline Cadillac Owners Enthusiast
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    Quote Originally Posted by joshk View Post
    hmmmm mine doesnt look exactly the same. do the update parts always look like the pictures above or could mine just be different? if i dont have the kit how much does it usually cost with and without install?

    <img src="http://www.cadillacforums.com/forums/attachment.php?attachmentid=119802"/>

    <img src="http://www.cadillacforums.com/forums/attachment.php?attachmentid=119810"/>
    That is the original setup so you don't have the new pcv setup which would explain the oil in your spark plug cavities. The oil is seeping through your valve cover gaskets and settling in those areas. I'd do the pcv upgrade and replace your valve cover gaskets at the same time.

  14. #13
    joshk is offline Cadillac Owners Member
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    Re: rough at idle only, but no check engine light

    ok i brought the car to chevy and since there is no check engine light they really couldnt find anything but they cleaned the throttle body and added cleaner stuff to the gas tank but still runs rough. i cleaned the maf sensor and opened up the throttle body and cleaned those connections but still nothing. i have read that there was an update to the 03 computer that raised the idle, and i asked about the flash to the computer at 2 dealerships and they said they could find nothing about it.

    im at a loss, i dont want to keep throwing money at this problem, so any other suggestions?

    also if you have had the update or know about it can you give me some information about it so i can explain what the chevy service department needs to look for.

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