Page 1 of 2 12 LastLast
Results 1 to 20 of 34

stumble when accelerate/rough idle

This is a discussion on stumble when accelerate/rough idle within the General Help forums, part of the LSx Technical Help Section category; couldnt find anything on any other threads, but lately my car will have a rough idle and stumble for a ...

  1. #1
    Member godless-phoenix's Avatar
    Join Date
    Jan 2010
    Location
    culver city, Ca.
    Posts
    459

    Blackened fire chicken
    2000 Pontiac Trans Am WS6

    stumble when accelerate/rough idle

    couldnt find anything on any other threads, but lately my car will have a rough idle and stumble for a second or two when accelerating from a stop. Its on and off and only happens after the car has warmed up. ive cleaned my MAF, throttle body, and ive also run fuel injector cleaner though it. i changed the plugs and wires last year in march, replaced all O2 sensors, and replaced the fuel filter last year as well...no check engine light either, any ideas? thanks!

  2. #2
    Electrical Engineer KMdef9's Avatar
    Join Date
    Jul 2009
    Location
    North of the Motorcity
    Posts
    2,611

    Custom Swirly Black
    2001 WS6 M6

    Check fuel pressure at the rails.

  3. #3
    Member godless-phoenix's Avatar
    Join Date
    Jan 2010
    Location
    culver city, Ca.
    Posts
    459

    Blackened fire chicken
    2000 Pontiac Trans Am WS6

    yeah i hope its not my fuel pump whats the pressure supposed to be at? like 60-65 lbs.?

  4. #4
    Electrical Engineer KMdef9's Avatar
    Join Date
    Jul 2009
    Location
    North of the Motorcity
    Posts
    2,611

    Custom Swirly Black
    2001 WS6 M6

    About there, I think 48 @ idle Iirc.

    Jon has the numbers.

  5. #5
    Member godless-phoenix's Avatar
    Join Date
    Jan 2010
    Location
    culver city, Ca.
    Posts
    459

    Blackened fire chicken
    2000 Pontiac Trans Am WS6

    its weird cause it only happens after the engine has warmed up to operating temperature, its on and off, and the car runs fine after i accelerate from a stop...just a rough idle and stumble when accelerating from stop for like a second

  6. #6
    None Shall Pass Knight's Avatar
    Join Date
    Jan 2010
    Location
    East of Cleveland, Ohio
    Posts
    3,828

    Black
    99 WS.6 - Modified

    You should see around 58 psi at the rail. You could still have it scanned, as it may have a code pending.

  7. #7
    None Shall Pass Knight's Avatar
    Join Date
    Jan 2010
    Location
    East of Cleveland, Ohio
    Posts
    3,828

    Black
    99 WS.6 - Modified

    When you replaced the O2 sensors, what brand did you use? Also, if you did it while installing LT's, did you splice the wiring, or run ones with longer harnesses?

  8. #8
    Member godless-phoenix's Avatar
    Join Date
    Jan 2010
    Location
    culver city, Ca.
    Posts
    459

    Blackened fire chicken
    2000 Pontiac Trans Am WS6

    Quote Originally Posted by Knight View Post
    You should see around 58 psi at the rail. You could still have it scanned, as it may have a code pending.
    i have a code scanner, and i actually did that just to check anyway...zero codes

  9. #9
    Member godless-phoenix's Avatar
    Join Date
    Jan 2010
    Location
    culver city, Ca.
    Posts
    459

    Blackened fire chicken
    2000 Pontiac Trans Am WS6

    Quote Originally Posted by Knight View Post
    When you replaced the O2 sensors, what brand did you use? Also, if you did it while installing LT's, did you splice the wiring, or run ones with longer harnesses?
    i used cheap ass SMP (standard motor products) O2 sensors from ebay that were like $20...i have stock manifolds

  10. #10
    Member godless-phoenix's Avatar
    Join Date
    Jan 2010
    Location
    culver city, Ca.
    Posts
    459

    Blackened fire chicken
    2000 Pontiac Trans Am WS6

    btw...what does iirc mean?

  11. #11
    None Shall Pass Knight's Avatar
    Join Date
    Jan 2010
    Location
    East of Cleveland, Ohio
    Posts
    3,828

    Black
    99 WS.6 - Modified

    iirc - if I recall correctly.

  12. #12
    Member godless-phoenix's Avatar
    Join Date
    Jan 2010
    Location
    culver city, Ca.
    Posts
    459

    Blackened fire chicken
    2000 Pontiac Trans Am WS6

    Quote Originally Posted by Knight View Post
    iirc - if I recall correctly.
    ahh, derrrr! damn acronyms haha

  13. #13
    Junior Member smokestack's Avatar
    Join Date
    May 2011
    Location
    Terre haute IN
    Posts
    74

    blue
    2001 silverado

    If you have a scanner make sure the cheap sensors are in spec or working. I bet if they are working not within spec and have your fueling messed up. Went through that myself. No codes but did not work.... Had to replace them

  14. #14
    Member godless-phoenix's Avatar
    Join Date
    Jan 2010
    Location
    culver city, Ca.
    Posts
    459

    Blackened fire chicken
    2000 Pontiac Trans Am WS6

    Quote Originally Posted by smokestack View Post
    If you have a scanner make sure the cheap sensors are in spec or working. I bet if they are working not within spec and have your fueling messed up. Went through that myself. No codes but did not work.... Had to replace them
    i have a cheap $80 scanner that only tells me what codes pop up. Doesnt even tell me what the code means, so i have to look them up...

  15. #15
    Senior Member JayTA98's Avatar
    Join Date
    Dec 2007
    Location
    Orlando, FL
    Posts
    3,351

    Mean Black
    1998 Trans Am

    It might be the O2 sensors out of specs like mentioned. Alot of the members use the boschs. Have you check the IAC? I had a few cars that it was stuck and dirty with carbon deposits. It never threw a SES light. I pulled it out cleaned it real good and made sure it was not stuck. It solved the idle problems.

  16. #16
    Junior Member
    Join Date
    Oct 2009
    Location
    katy, tx
    Posts
    1

    white
    2000 trans am

    I have been chasing the same problem for about a year now and followed the same path you're on (changed plugs 4 times - never had a car that was so painful to change plugs!) Anyway, after cleaning and/or replacing all of the things mentioned above with no fix, this week we found that the MAP sensor is not working. I finally found a guy who had the right equipment ( a sophisticated scanner) and he had time to go through everything, like what does the computer think the O2 is and what does a gauge in one of the bungs see, etc. Another often-quoted possiblity was a leak in the intake - we sprayed carburetor cleaner around the hoses, manifold, etc., with the idea that if it hits a leak the engine will respond. Good luck!

  17. #17
    Junior Member Intimidator02SS's Avatar
    Join Date
    Aug 2006
    Location
    Georgia
    Posts
    13

    Black
    2002 Camaro SS

    try disconnecting your mass air flow sensor and see if symptoms disappear.

  18. #18
    Member godless-phoenix's Avatar
    Join Date
    Jan 2010
    Location
    culver city, Ca.
    Posts
    459

    Blackened fire chicken
    2000 Pontiac Trans Am WS6

    Quote Originally Posted by JayTA98 View Post
    It might be the O2 sensors out of specs like mentioned. Alot of the members use the boschs. Have you check the IAC? I had a few cars that it was stuck and dirty with carbon deposits. It never threw a SES light. I pulled it out cleaned it real good and made sure it was not stuck. It solved the idle problems.
    how do i check to see if the iac is stuck? i know take it out, but do i just push it in or turn it? dont want to mess that up, cause for that little part its expensive! taking it in next tuesday to have it checked out cause im stumped...

  19. #19
    Electrical Engineer KMdef9's Avatar
    Join Date
    Jul 2009
    Location
    North of the Motorcity
    Posts
    2,611

    Custom Swirly Black
    2001 WS6 M6

    Quote Originally Posted by godless-phoenix View Post
    how do i check to see if the iac is stuck? i know take it out, but do i just push it in or turn it? dont want to mess that up, cause for that little part its expensive! taking it in next tuesday to have it checked out cause im stumped...
    It moves by electricity, controlled from the PCM. Just give it a good spray/wipe down and reinstall. DON'T pull on it.

  20. #20
    Member godless-phoenix's Avatar
    Join Date
    Jan 2010
    Location
    culver city, Ca.
    Posts
    459

    Blackened fire chicken
    2000 Pontiac Trans Am WS6

    Quote Originally Posted by KMdef9 View Post
    It moves by electricity, controlled from the PCM. Just give it a good spray/wipe down and reinstall. DON'T pull on it.
    should i spray it with maf cleaner or throttle body cleaner? thanks for the tip on not pulling it btw haha
    Last edited by godless-phoenix; 01-19-2012 at 08:29 AM.

Page 1 of 2 12 LastLast

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Help: intermittant rough idle, off idle hesitation
    By Matto4785 in forum General Help
    Replies: 1
    Last Post: 09-21-2009, 06:12 AM
  2. Help: rough idle
    By RLamas in forum Firebird / WS6
    Replies: 8
    Last Post: 05-01-2009, 05:59 PM
  3. Rough Idle
    By smkeater911 in forum General Help
    Replies: 13
    Last Post: 08-30-2008, 12:32 PM
  4. Rough Idle
    By MSz28 in forum General Help
    Replies: 19
    Last Post: 04-23-2007, 12:48 PM
  5. Rough Idle
    By damac in forum General Help
    Replies: 8
    Last Post: 05-25-2006, 06:43 AM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •