Page 1 of 3 123 LastLast
Results 1 to 10 of 21

Thread: Idle issue IAC steps

  1. #1
    Never finishes any verified
    Feedback Score 8 (100%) DrGonzo's Avatar
    Join Date
    Sep 2010
    Owner Since
    2001

    Location
    Wake Forest, NC
    Posts
    2,569
    Thanks
    54
    Thanked 197 Times in 140 Posts

    Angry Idle issue IAC steps

    When I drive the car around and let off the gas the rpm's stay at about 2500-3000 rpm's for almost 25 seconds and then the idle drops down to normal.

    I thought it may have been from a vacuum leak but the pressure test came back with no leaks at all. The just installed a rebuilt TT throttle body with all new seals and adjusted to spec. IAC and TPS all tested fine.

    So I looked at my log files and noticed after I let off the throttle the IAC steps stay between 85-89 then they suddenly drop after 20 seconds.

    Anyone have any ideas what would cause this type of behavior? it is really annoying as when ever I stop at a light or stop sign the car sits there at almost 3000rpms and finally drops back to idle.

    here is the log file and I have the occurance highlighted in red:

    http://3s.gonzoinc.com/albums/userpi...3_16_45_31.xls

    I can't seem to figure this one out!!!!!!

    Check it out on Youtube!!


    93 Stealth TT - The Stealth Project

    Renegade Tech Works ECS Controller on Intrax Springs
    Chrome ECU
    Hybrid 13g's
    EVO 560cc Injectors
    Spec Stage 3 clutch
    Ninja Performance Output shaft & Input spool
    Ninja Performance Solid Tensioner & Gates racing T-Belt
    CX Racing Dual Core FMIC
    Megan SS Exhaust
    Fidanza Cam Gears and Clear Covers
    3rd Gen Lifters
    HKS BOV
    K&N FIPK
    Maximal High flow converter
    Walbro FP & FuelLab FPR
    Maximal and Seattle Solid Mounts
    All -6an Lines
    Custom -6AN coolant neck lines
    AWS/ABS/Cruise Delete
    MP Rear Control Arms
    SS Brake Lines
    99 Front Conversion
    2nd gen Rear Bumper
    99 Combat Wing
    Complete interior LED Swap
    Skillard Fuel channel
    Oohnoo FPR Bracket
    .
    .
    More to Come......

  2. #2
    Here for the party Not Verified Feedback Score 1 (100%) CoreyB's Avatar
    Join Date
    Sep 2010
    Owner Since
    2006

    Location
    Canaan NH
    Posts
    1,749
    Thanks
    368
    Thanked 108 Times in 89 Posts
    Is the TPS set so the idle switch is being triggered ?

  3. #3
    Never finishes any verified
    Feedback Score 8 (100%) DrGonzo's Avatar
    Join Date
    Sep 2010
    Owner Since
    2001

    Location
    Wake Forest, NC
    Posts
    2,569
    Thanks
    54
    Thanked 197 Times in 140 Posts
    TPS was adjusted just like is states in the manual.

    0.65 Feeler gauge was inserted between SAS screw and throttle lever, TPS was turned until continuity was lost between terminals 3-4.

  4. #4
    Here for the party Not Verified Feedback Score 1 (100%) CoreyB's Avatar
    Join Date
    Sep 2010
    Owner Since
    2006

    Location
    Canaan NH
    Posts
    1,749
    Thanks
    368
    Thanked 108 Times in 89 Posts
    Ok, was just the first thought I had. Its a long shot but could your blow off valve be sticking open for a little while ?

  5. #5
    Never finishes any verified
    Feedback Score 8 (100%) DrGonzo's Avatar
    Join Date
    Sep 2010
    Owner Since
    2001

    Location
    Wake Forest, NC
    Posts
    2,569
    Thanks
    54
    Thanked 197 Times in 140 Posts
    It's is not the BOV. If you take a look at the log I attached you will see that the IAC is still sitting at 89 counts even when I let off the throttle. Something "ECU/Electrical" is causing the IAC to stay open when it shouldn't be.

  6. #6
    Forum User verified Feedback Score 2 (100%)
    Join Date
    Sep 2010
    Owner Since
    2008

    Location
    CT
    Posts
    481
    Thanks
    36
    Thanked 14 Times in 12 Posts
    Things that effect ISC speed (usually switches or sensors)
    power steering
    air conditioner
    altitude
    talons had some sort of training function that changes values over time, we might have this as well
    deceleration from cruise or racing speed so that air is not cut off to quickly
    coolant temperature

    loggers should be able to check that stuff as well. what kind of speed are you at while letting off the throttle? im also not sure what this training function is but an ECU reset might fix it.

    I wouldn't take this as anything other than stuff no one has mentioned yet. We know for sure the ECU is keeping that step high, and its got to be for a reason. Because it drops down after a short while im really wondering what it could be.

  7. #7
    Never finishes any verified
    Feedback Score 8 (100%) DrGonzo's Avatar
    Join Date
    Sep 2010
    Owner Since
    2001

    Location
    Wake Forest, NC
    Posts
    2,569
    Thanks
    54
    Thanked 197 Times in 140 Posts
    So after some advise from one of the guys on the other site I found out what the FLG0 - FLG2 means on the logger. They are flags for certain switches being on/off. FLG0 has an entry for Idle switch "I".

    So I checked the logger with the car in just the on position and nothing. I tried moving the TPS around some and still nothing. Can't export the log as it keeps crashing MMCD Tools doing the export.

    I would get random T-AN-- when I would move the TPS around which doesn't make any sense to me! TDC is the only one of those sensors even close to the vicinity of the TPS sensor. The AC was not even turned on.

    T-Top Dead Center
    A-AC load Switch
    N-Neutral

    I took the TPS off and tested it with a multimeter and I am getting continuity through pins 3-4 but I have to run the inside plate a little. When I installed the TPS I adjusted it so that when the throttle plate was closed I had continuity! WTF???

    I have a couple TPS sensors I am going to swap in tomorrow and see what I get then.

  8. #8
    Padawan garage troll Not Verified Feedback Score 1 (100%) Roybatty's Avatar
    Join Date
    Sep 2010
    Owner Since
    2004

    Location
    Newark, DE
    Posts
    672
    Blog Entries
    5
    Thanks
    70
    Thanked 24 Times in 22 Posts
    Sounds like u r following service manual Fuel section. There is a pretty good trouble shooting section there imho, which I suggest u check out and follow. Tps is basically a potentiometer, and sends this signal to ecu as throttle depressed.

    Sent from my Eris using Tapatalk
    91 AWD TT
    K&N FIPK, Precats gutted, Test Pipe, Blitz DSBC, Walbro 255, Vacuum reduction, SM3, MMCd, Krank Vents, 3SX Aluminum Crank Pulley, Aluminum 2PC DS, MAFT Pro (AFC mode atm).

    To do list: Need to check electronic timing, install FP hotwire, install PS poly MM, RUACAs, Setrab oil cooler, Dejon Y-pipe, 3.5 GM Mas, FIC 650ccs & 13Ts.

  9. #9
    Never finishes any verified
    Feedback Score 8 (100%) DrGonzo's Avatar
    Join Date
    Sep 2010
    Owner Since
    2001

    Location
    Wake Forest, NC
    Posts
    2,569
    Thanks
    54
    Thanked 197 Times in 140 Posts
    Quote Originally Posted by Roybatty View Post
    Sounds like u r following service manual Fuel section. There is a pretty good trouble shooting section there imho, which I suggest u check out and follow. Tps is basically a potentiometer, and sends this signal to ecu as throttle depressed.

    Sent from my Eris using Tapatalk
    Followed the manly and double checked everything multiple times. Te idle switch is working and the ECU is seeing it but it refuses to drop the IAC steps back down. Something else is telling it to stay higher and I can't seem to track it down. ECS and ABS have been disabled/deleted so I don't know what else could cause the ECU to see that it needs more airflow.

  10. #10
    Here for the party Not Verified Feedback Score 1 (100%) CoreyB's Avatar
    Join Date
    Sep 2010
    Owner Since
    2006

    Location
    Canaan NH
    Posts
    1,749
    Thanks
    368
    Thanked 108 Times in 89 Posts
    Power steering switch ?

Page 1 of 3 123 LastLast

Tags for this Thread

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
  •  
The 3000GT/Stealth/GTO Web History Project
3000gt.com
3000GT / Stealth International WWWboard Archive
Jim's (RED3KGT) Reststop
3000GT/Stealth/GTO Information and Resources
Team 3S
3000GT / Stealth / GTO Information
daveblack.net
3000GT/Stealth/GTO Clubs and Groups
Michigan 3S
MInnesota 3S
Wisconsin 3S
Iowa, Nebraska, Kansas 3S
North California 3000GT/Stealth
United Society of 3S Owners
3000GT/Stealth/GTO Forums
3000GT/Stealth International
3000GT/Stealth/GTO Event Pages
3S National Gathering
East Coast Gathering
Upper Mid-West Gathering
Blue Ridge Gathering