Page 1 of 2 12 LastLast
Results 1 to 20 of 30

Slightly rough idle?

This is a discussion on Slightly rough idle? within the General Help forums, part of the LSx Technical Help Section category; My car is a '99 M6 LS1 pretty much stock with 45k miles on the odometer. I'm not sure what ...

  1. #1
    Member Aetos's Avatar
    Join Date
    May 2008
    Location
    Formerly NYC. Strong Island now!!
    Age
    29
    Posts
    641

    White
    1999 Transam WS6

    Slightly rough idle?

    My car is a '99 M6 LS1 pretty much stock with 45k miles on the odometer.
    I'm not sure what has been changed on the car since its purchase since I recently purchased the car.

    Problem: The cars idle is a bit rough/shaky at idle, but the RPMs are always steady at I would say a 800 range or so. While looking in the engine bay with the car in idle you can see the engine pretty steady but every so often you will see it shake/tremor a bit then see it go back to a pretty much steady pace, but the idle will always stay static in this process.

    What could be the cause of this(spark plugs, maybe? random misfire?) I don't have any codes popping up.

    Could this also have something to do with my seemingly bad MPG? I was thinking that about 150miles on a tank was standard, but after reading some threads about people getting 200-300mpg on a tank I'm having my doubts.

  2. #2
    Internet Tough Guy Fury_786's Avatar
    Join Date
    Nov 2007
    Location
    Oregon
    Age
    31
    Posts
    698

    Sinister, SixGun
    2001 SS, 2002 L36 M5

    mine does it sometimes...its an LS1 thing

    changing the plugs/wires sometimes makes it smoother, sometimes not

  3. #3
    Member Aetos's Avatar
    Join Date
    May 2008
    Location
    Formerly NYC. Strong Island now!!
    Age
    29
    Posts
    641

    White
    1999 Transam WS6

    Quote Originally Posted by Fury_786 View Post
    mine does it sometimes...its an LS1 thing

    changing the plugs/wires sometimes makes it smoother, sometimes not

    how about the low MPG? lol

  4. #4
    Just a slow Camaro KING Z28 HAWK's Avatar
    Join Date
    Oct 2007
    Location
    Fresno Ca
    Posts
    2,228

    LPM
    2002 Z28 Camaro

    Quote Originally Posted by Aetos View Post
    My car is a '99 M6 LS1 pretty much stock with 45k miles on the odometer.
    I'm not sure what has been changed on the car since its purchase since I recently purchased the car.

    Problem: The cars idle is a bit rough/shaky at idle, but the RPMs are always steady at I would say a 800 range or so. While looking in the engine bay with the car in idle you can see the engine pretty steady but every so often you will see it shake/tremor a bit then see it go back to a pretty much steady pace, but the idle will always stay static in this process.

    What could be the cause of this(spark plugs, maybe? random misfire?) I don't have any codes popping up.

    Could this also have something to do with my seemingly bad MPG? I was thinking that about 150miles on a tank was standard, but after reading some threads about people getting 200-300mpg on a tank I'm having my doubts.
    Sounds like a normal LS1 but MPG might want to change you fuel filter and air filter see if that hels any

  5. #5
    Member Aetos's Avatar
    Join Date
    May 2008
    Location
    Formerly NYC. Strong Island now!!
    Age
    29
    Posts
    641

    White
    1999 Transam WS6

    Quote Originally Posted by KING Z28 HAWK View Post
    Sounds like a normal LS1 but MPG might want to change you fuel filter and air filter see if that hels any
    The air filter seems fine, but haven't checked the fuel filter. The shake isn't only visual on the engine though. You can feel the car and the shifter shaking at idle also.

  6. #6
    Internet Tough Guy Fury_786's Avatar
    Join Date
    Nov 2007
    Location
    Oregon
    Age
    31
    Posts
    698

    Sinister, SixGun
    2001 SS, 2002 L36 M5

    i get 28hwy, 18/city with 3.90 gears

    and yes, i drive it like i stole it

    mine shakes like a epileptic on crack

    2001 M6 SS - few mods...

  7. #7
    Member Aetos's Avatar
    Join Date
    May 2008
    Location
    Formerly NYC. Strong Island now!!
    Age
    29
    Posts
    641

    White
    1999 Transam WS6

    Quote Originally Posted by Fury_786 View Post
    i get 28hwy, 18/city with 3.90 gears

    and yes, i drive it like i stole it

    mine shakes like a epileptic on crack
    I get nowhere near that!!!! I'm lucky to get 150-160 a tank!!
    I don't always push it either, a lot of times I'm shifting at like 2krpm


  8. #8
    Internet Tough Guy Fury_786's Avatar
    Join Date
    Nov 2007
    Location
    Oregon
    Age
    31
    Posts
    698

    Sinister, SixGun
    2001 SS, 2002 L36 M5

    geeze

    1. fuel filter
    2. spark plugs
    3. wires
    4. 02 sensors

  9. #9
    Member Aetos's Avatar
    Join Date
    May 2008
    Location
    Formerly NYC. Strong Island now!!
    Age
    29
    Posts
    641

    White
    1999 Transam WS6

    Quote Originally Posted by Fury_786 View Post
    geeze

    1. fuel filter
    2. spark plugs
    3. wires
    4. 02 sensors
    If either of these bad wouldn't it throw some kind of code? atleast the 02/plugs would?

  10. #10
    Internet Tough Guy Fury_786's Avatar
    Join Date
    Nov 2007
    Location
    Oregon
    Age
    31
    Posts
    698

    Sinister, SixGun
    2001 SS, 2002 L36 M5

    not necessarily. they can be performing badly, and the PCM wont notice

    alot of times they can mess up the AFR and have a code, but never a SES light.

  11. #11
    Senior Member INMY01TA's Avatar
    Join Date
    Jan 2006
    Location
    The great red state of MD.
    Posts
    5,755

    Black
    2001 Trans Am (sold)

    Clean the maf too.

  12. #12
    Member Aetos's Avatar
    Join Date
    May 2008
    Location
    Formerly NYC. Strong Island now!!
    Age
    29
    Posts
    641

    White
    1999 Transam WS6

    Quote Originally Posted by Fury_786 View Post
    not necessarily. they can be performing badly, and the PCM wont notice

    alot of times they can mess up the AFR and have a code, but never a SES light.


    Think it would be worth a shot to check for codes even if no dash light pops?

  13. #13
    Internet Tough Guy Fury_786's Avatar
    Join Date
    Nov 2007
    Location
    Oregon
    Age
    31
    Posts
    698

    Sinister, SixGun
    2001 SS, 2002 L36 M5

    wouldnt hurt any adv. auto could do it for free.

    and as 01TA just said, check the MAF, sometimes they get a piece of fuzz or something in there and makes them go crazy

  14. #14
    O U 8 1 2 Spaz's Avatar
    Join Date
    Nov 1999
    Location
    over here...
    Age
    39
    Posts
    25,693

    []D [] []V[] []D
    1999 trans am

    Quote Originally Posted by Fury_786 View Post
    geeze

    1. fuel filter
    2. spark plugs
    3. wires
    4. 02 sensors
    Quote Originally Posted by INMY01TA View Post
    Clean the maf too.


    check your air filter as well...

    fuel filters should be changed with every 3rd oil change... easy to swap out and cheap...

  15. #15
    Junior Member ws_sick's Avatar
    Join Date
    Jul 2008
    Location
    Cape Coral, Florida
    Posts
    15

    white
    2002 ws6

    I would start with the normal maintence mentioned above, if that doesnt work, you could have a leaking injector, that would explain the poor fuel mileage and rough running, also, does it shake when the a/c is on, off, or both? could be your compressor cycling

  16. #16
    TunedbyFrost.com Tuner Frost's Avatar
    Join Date
    Jul 2007
    Location
    Richmond VA
    Posts
    2,415

    LS1.com Sponsor
    GM Tuner

    To maintain fuel economy, you need to replace your front O2s every 40K miles or 3 years if internally stock / still running manifolds or every 15-20K (with monitoring) if running headers, even if internally stock.

    The problem with them is that they hardly ever fail outright (unless the heater fails), and over time they drift off. As they foul, the senor's exposure area is naturally fouled as well. This layer of "insulation" causes them to report leaner conditions, since more of the oxygen that they "see" is kept away from the sensor. As they report a little leaner, the engine responds by adding a little more fuel than it needs in closed loop. Basically, this is any time that the engine is over about 92 degrees and not at WOT. What I am saying is that they are basically in charge of your car's fueling all of the time except near WOT.

    If mileage is really suffering, these guys are hands-down the most likely culprit.

  17. #17
    Internet Tough Guy Fury_786's Avatar
    Join Date
    Nov 2007
    Location
    Oregon
    Age
    31
    Posts
    698

    Sinister, SixGun
    2001 SS, 2002 L36 M5

    sometimes you can temp. fix an 02 sensor by cleaning the carbon/buildup off od the tip

    but its much better to just spring for some new ones at about $100/pr

  18. #18
    Member Aetos's Avatar
    Join Date
    May 2008
    Location
    Formerly NYC. Strong Island now!!
    Age
    29
    Posts
    641

    White
    1999 Transam WS6

    Scanned the codes and no codes were thrown

    I think the first thing I'm gonna do is change out the 02s... now.. wheres the best price for 02s?


    edit:

    Without throwing any codes whats the thing that could affect the mileage the most? (shouldn't bad 02's throw codes?)
    Last edited by Aetos; 07-31-2008 at 05:01 PM.

  19. #19
    Old Enough to Know Better Crimson Sin's Avatar
    Join Date
    Feb 2006
    Location
    Seattle..Land of Constant Rain..
    Posts
    1,426

    Red Fire
    2007 Mustang GT/CS

    Read what Frost said about the sensor's, pretty spot on. I would just change them.. And it doesn't matter where ya get them.. a Bosch O2 is a Bosch O2..Just get the OEM style ( not the universal, wire the plug on yourself crap)..And yep, your mileage is in the toilet. I get 25 on the hwy. 3.73's with an stalled A4...Hell, do a tune up. Seafoam it, clean the maf and change your filters.
    Do Not Anger the Horsepower Gods ! MOD !!

    2007 Mustang GT/CS
    2001 SS Cammed. Stalled. Geared. Tuned...Gone but not forgotten..
    Quote Originally Posted by bluefields88 View Post
    pornhub.com has a tribute thing for MJ at the top of page. I can't even jerk off without being bombarded by the bastard.


  20. #20
    Old Enough to Know Better Crimson Sin's Avatar
    Join Date
    Feb 2006
    Location
    Seattle..Land of Constant Rain..
    Posts
    1,426

    Red Fire
    2007 Mustang GT/CS

    Most code *scanners* are crap, that's why they are 100 or so. Unless you have a MODIS or an OTC Genisys or similar, you can't read live data or freeze frame data. SO, unless they have failed, you can't tell dick. I have NO codes on my car, but lo and behold. I hooked up the Genisys and there's 125 or so items in stored memory. Most of it is normal stuff. But some is shit that should be looked into. A/F rates off etc..Hell, I had random misfires on all cylinders a few months back ( wires were WAY over on resistance) No SES light tho ( codes ). The local parts shops will pull codes for free, sure. You get what ya pay for tho. Most quality scanners are a few thousand dollars for a reason.. If you really wanna know, pay a reputable shop the 80-100 bucks to scan your PCM and show you the results. I do it all the time for guys that ask and aren't a dick about the charge.

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: Rough Idle
    By 1WickedWS6 in forum GM Trucks
    Replies: 12
    Last Post: 01-04-2012, 08:16 AM
  2. Help: intermittant rough idle, off idle hesitation
    By Matto4785 in forum General Help
    Replies: 1
    Last Post: 09-21-2009, 06:12 AM
  3. Help: rough idle
    By RLamas in forum Firebird / WS6
    Replies: 8
    Last Post: 05-01-2009, 05:59 PM
  4. Rough Idle
    By kinsey850 in forum General Help
    Replies: 8
    Last Post: 06-13-2008, 07:49 PM
  5. Z28 Still Has Rough Idle Wtf????
    By LETHALxLS1 in forum Camaro / SS
    Replies: 72
    Last Post: 02-01-2008, 03:07 PM

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
  •