Thread: Random very high / fast idle speed...

Results 1 to 6 of 6
  1. #1 Random very high / fast idle speed... 
    SE Level Member
    Join Date
    Feb 2009
    Location
    NE
    Posts
    53
    Thanks (Received)
    0
    Likes (Received)
    0
    Dislikes (Received)
    0
    About every 3 times my daughter drives her 97 GT she says it idles at around 2500 RPMs. I saw it doing it today myself and checked the throttle plate was returning to the stop and it was. I changed the IAC with a know good one off my son's 98 GT a few weeks ago. Also swapped the TPS & MAF sensors. I had put a new upper intake on the 97 last winter so I am not thinking that it could have an upper intake vacuum leak. Any common items I can check or ways to test for vacuum leaks?
    Reply With Quote  
     

  2. #2 Re: Random very high / fast idle speed... 
    GTX Level Member cerick08GP's Avatar
    Join Date
    Sep 2009
    Location
    Wisconsin
    Posts
    782
    Thanks (Received)
    0
    Likes (Received)
    0
    Dislikes (Received)
    0
    I would check the fuel injector O-rings.

    Ten years of continuous driving excitement and counting!
    2008GP
    ||HV3 insert||PowerSlot rotors w/Hawks||LED interior||MSD 8.5mm
    2002GP||sold
    Reply With Quote  
     

  3. #3 Re: Random very high / fast idle speed... 
    Donating Users Liquifire's Avatar
    Join Date
    Jun 2009
    Location
    Wausau, WI
    Posts
    2,373
    Thanks (Received)
    0
    Likes (Received)
    0
    Dislikes (Received)
    0
    take some carb cleaner and start spraying around the intake manifold area, and also around any vacuum lines/connections with the car running. If your car idles pick up in any one area, you have found the leak. Spray liberally....
    98 GTP Coupe- 180* T-stat, GMPP Front Sway Bar, Dual Aeroforce Interceptor's, TDC FWI, TDC Taylor 10.4's, ZZP SS Plog, ZZP 3" SS catted DP, ZZP MPS W/3.4, AL104's gapped @.055, 3800Perf. PCM
    Reply With Quote  
     

  4. #4 Re: Random very high / fast idle speed... 
    The Blue One blueguy's Avatar
    Join Date
    Jun 2008
    Location
    Dirtyzville, Missery
    Posts
    31,287
    Thanks (Received)
    1
    Likes (Received)
    2
    Dislikes (Received)
    0
    I bet dry rot.

    Check all the black rubber "T" fittings around the fuel rail, TB, and LIM
    Sold WBody's: '03 Blue GTP/'98 Green GTP/'98 Silver GT/'05 GXP
    '99 Chevrolet Silverado Classic Z71 4x4 - K&N Intake/Gibson Exhaust #TRUCKTHINGS
    '12 Buick Regal Turbo - ZZP CAI/20% Tint/HID's
    '89 Ford Mustang LX Notchback - LM7 5.3, 4L80, 9", HX40
    '04 Chevrolet Corvette MRM A4/LS1 - TSP LT's, 3"O/R X, AFE S2 CAI
    Reply With Quote  
     

  5. #5 Re: Random very high / fast idle speed... 
    SE Level Member
    Join Date
    Aug 2012
    Posts
    2
    Thanks (Received)
    0
    Likes (Received)
    0
    Dislikes (Received)
    0
    Im having the same problem. The dealer says I need a new PCM. No check engine light. Internal short or something. Sending signal to the throttle. First thing in the morning its ok. I can make the idle stick high almost on demand holding the brake in drive and pushing the peddle. When its doing this it shifts funky like 4500 rpm most of the time. At lights ive been popping into neutral and dropping it befor i go. Hopefully wont cook the tranny befor its fixed.

    700 bux though at dealer is crazy, 20 at the wrecker, but all i read is i cant just swap pcm's. But im gonna try first. then maybe order one on the net for 125 with my vin, and they will program.

    got an 03 gt 3.8,
    Reply With Quote  
     

  6. #6 Re: Random very high / fast idle speed... 
    Turbo is the way to go. Fivefingerdeathpunch's Avatar
    Join Date
    Sep 2009
    Location
    Rogers, MN
    Posts
    21,030
    Thanks (Received)
    21
    Likes (Received)
    45
    Dislikes (Received)
    0
    You can find a 03 PCM and try swapping it for cheap, thats quick atleast. Just unhook the battery, unbolt the PCM and swap it.

    I assume you've tried unplugged the TPS sensor as well as the IAC sensor and seeing if the idle drops or stays the same.

    And made sure the thorttle cable is not kinked and is not stuck sometimes.

    SMGPFC Member #1
    Reply With Quote  
     

Similar Threads

  1. Replies: 25
    Last Post: 09-01-2010, 05:49 AM
  2. High idle?
    By WhiteGT in forum 3.8L V6 Naturally Aspirated (L36)(L26)
    Replies: 15
    Last Post: 10-15-2009, 02:14 AM
  3. 98 GTP high idle problem
    By mikegtp in forum General Tech Discussion
    Replies: 5
    Last Post: 10-09-2009, 02:05 PM
  4. High / Fast Idle - Idle Air Control motor?
    By porshuh in forum 3.8L V6 Supercharged (L67)(L32)
    Replies: 0
    Last Post: 07-30-2009, 11:28 AM
  5. fast high low idle
    By gtchris in forum 3.8L V6 Supercharged (L67)(L32)
    Replies: 1
    Last Post: 02-15-2009, 04:17 PM
Tags for this Thread

View Tag Cloud

Bookmarks
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
  •