Hunting idle after cold start up
Welcome guest, is this your first visit? Click the "Create Account" button now to join.

User Tag List

Page 1 of 2 1 2 LastLast
Results 1 to 10 of 12
Like Tree2Likes

Thread: Hunting idle after cold start up

  1. #1
    FST Member Rein_FOST's Avatar
    This user has no status.
     

    Join Date
    Jan 2017
    Posts
    12
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Hunting idle after cold start up

    Hi all

    Trust all is well.

    My cars idling suddenly changed. On cold start (cold engine) for when car stood for overnight or 8 hours moreor less during work day.

    It will idle fine at 1200 rpms and as engine warms up and revs begin to drop to 800rpms it will ilde fine and then suddenly start to spike again to 1200 and drop back to 800.

    This continues for another 30odd seconds till it idles normally at 800.

    I did a visual inspection on the vacuum line that runs from plenum but couldn't see a fault.

    What could be causing this other than perhaps a vacuum leak?

    Car is the st225 2.5l.

    Kind regards

    Sent from my F8331 using Tapatalk

  2. #2
    FST Junkie! elyk864's Avatar
    is here
     

    Join Date
    Feb 2013
    Location
    Anthem, AZ
    Posts
    1,868
    Mentioned
    34 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Rein_FOST View Post
    Hi all

    Trust all is well.

    My cars idling suddenly changed. On cold start (cold engine) for when car stood for overnight or 8 hours moreor less during work day.

    It will idle fine at 1200 rpms and as engine warms up and revs begin to drop to 800rpms it will ilde fine and then suddenly start to spike again to 1200 and drop back to 800.

    This continues for another 30odd seconds till it idles normally at 800.

    I did a visual inspection on the vacuum line that runs from plenum but couldn't see a fault.

    What could be causing this other than perhaps a vacuum leak?

    Car is the st225 2.5l.

    Kind regards

    Sent from my F8331 using Tapatalk
    Iv'e been getting some odd idle issues also, but car has thrown a Evap Leak code a couple times now. I just need to take it in and get that fixed. I googled it a bit and it seems to be a common problem so it should be an easy fix.
    Stratified Custom Tune (91 and E30)
    CPE FMIC
    VelossaTech Intake Snorkel
    FSwerks Shift Bracket (40%)
    FSwerks Shift Bracket Bushings
    Denso ITV22 Spark Plugs
    Green Filter
    Steeda RMM
    Gloss black wrapped roof
    TSW Rivage 18X8 5-108 +40mm
    Husky Liner Floor mats (All)
    Global windows mod
    Fogs on with High Beam mod (Diode Dynamics XML2 Fogs)
    Limo tint rear, Front legal
    Proclip Pillar mount
    Led Interior lights
    Breedt APM

  3. #3
    Super Moderator XRJoe's Avatar
    Premium Member
    is -
     

    Join Date
    Dec 2012
    Posts
    7,297
    Mentioned
    188 Post(s)
    Tagged
    4 Thread(s)
    Quote Originally Posted by Rein_FOST View Post
    Hi all

    Trust all is well.

    My cars idling suddenly changed. On cold start (cold engine) for when car stood for overnight or 8 hours moreor less during work day.

    It will idle fine at 1200 rpms and as engine warms up and revs begin to drop to 800rpms it will ilde fine and then suddenly start to spike again to 1200 and drop back to 800.

    This continues for another 30odd seconds till it idles normally at 800.

    I did a visual inspection on the vacuum line that runs from plenum but couldn't see a fault.

    What could be causing this other than perhaps a vacuum leak?

    Car is the st225 2.5l.

    Kind regards

    Sent from my F8331 using Tapatalk
    Could be a sensor issue as well. Has the weather changed recently where you are? Assuming somewhere in Europe.

    Has the car been remapped? Any mods?
    #LylaStrong

    Joe

    2013 Focus ST
    1985 Merkur XR4Ti

    Confused by acronyms? http://www.focusst.org/forum/focus-s...ons-terms.html

  4. Remove Advertisements
    FocusST.org
    Advertisements
     

  5. #4
    FST Member Rein_FOST's Avatar
    This user has no status.
     

    Join Date
    Jan 2017
    Posts
    12
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Hi @XRJoe

    No, no weather changes. The does have an unknown map. I am planning on doing an stage 2 upgrade at the end of next month.

    Ill remove and clean map and maf sensors on the weekend and see if there is an improvement.

    If not I guess I then need to take it in. I have displaced my obd scanner so waiting on new one to check for any errors.

    Sent from my F8331 using Tapatalk

  6. #5
    FST Junkie! LMStone510's Avatar
    is digging Griot's Garage clay!
     

    Join Date
    Apr 2013
    Location
    Maine
    Posts
    1,596
    Mentioned
    49 Post(s)
    Tagged
    1 Thread(s)
    It's normal, at least according to Alex at Stratified when I asked him.

    There are as you know even in the stock tune a gazillion tables for timing, idle etc. etc. etc...

    The car runs a faster idle driven by some tables to warm up the catalytic converter. There are other tables that control idle speed based on whether the car is warmed up or not.

    Alex described to me that, as the car is warming up, these two (sets of?) tables conflict, and the idle will hunt some for a few minutes. Blip the throttle and it almost always goes away. But if not, no big deal as it will go away when the car warms up anyway.

    BTW, a minor vacuum leak will not result in an idle speed increase, because our cars have MAP, not MAF sensors. The car just adjusts fuel to a desired mixture and doesn't care too much where the air is coming from (within reason).

    Hope that helps,
    Mark
    elyk864 likes this.



    2013 Race Red ST1
    Who is "General Failure"? And why is he reading my hard disk??


  7. #6
    FST Member Rein_FOST's Avatar
    This user has no status.
     

    Join Date
    Jan 2017
    Posts
    12
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Thanks @LMStone510 .

    That makes sense yes, I actually did read about that tables somewhere when I was looking at something else.

    I was only worried because the car never did that. It would have just idled at 1200 at startup and drop to 800. This just started from last week so was a bit worried.

    Sent from my F8331 using Tapatalk

  8. #7
    Super Moderator XRJoe's Avatar
    Premium Member
    is -
     

    Join Date
    Dec 2012
    Posts
    7,297
    Mentioned
    188 Post(s)
    Tagged
    4 Thread(s)
    Quote Originally Posted by LMStone510 View Post
    It's normal, at least according to Alex at Stratified when I asked him.

    There are as you know even in the stock tune a gazillion tables for timing, idle etc. etc. etc...

    The car runs a faster idle driven by some tables to warm up the catalytic converter. There are other tables that control idle speed based on whether the car is warmed up or not.

    Alex described to me that, as the car is warming up, these two (sets of?) tables conflict, and the idle will hunt some for a few minutes. Blip the throttle and it almost always goes away. But if not, no big deal as it will go away when the car warms up anyway.

    BTW, a minor vacuum leak will not result in an idle speed increase, because our cars have MAP, not MAF sensors. The car just adjusts fuel to a desired mixture and doesn't care too much where the air is coming from (within reason).

    Hope that helps,
    Mark
    Quote Originally Posted by Rein_FOST View Post
    Thanks @LMStone510 .

    That makes sense yes, I actually did read about that tables somewhere when I was looking at something else.

    I was only worried because the car never did that. It would have just idled at 1200 at startup and drop to 800. This just started from last week so was a bit worried.

    Sent from my F8331 using Tapatalk
    Just remember we're talking about the Mk2 ST225 (2.5l Volvo motor). I'm not sure what from the Mk3 ports back over to the older engine and management.
    #LylaStrong

    Joe

    2013 Focus ST
    1985 Merkur XR4Ti

    Confused by acronyms? http://www.focusst.org/forum/focus-s...ons-terms.html

  9. #8
    FST Member Rein_FOST's Avatar
    This user has no status.
     

    Join Date
    Jan 2017
    Posts
    12
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Since idling is runnig of tables which is based on air density I guess.

    Could it be that one of the lambda sensors is not working properly or on their way out. As the also measure air and I know some of them have an heating element to warm the sensor for when exhaust is still cold.

    So if cold or not working properly it sends wrong values and then wrong readings is made from idling tables?

    I don't have cel on. Will scan tomorrow to check if I have any dtc codes.

    Sent from my F8331 using Tapatalk

  10. #9
    FST Junkie! LMStone510's Avatar
    is digging Griot's Garage clay!
     

    Join Date
    Apr 2013
    Location
    Maine
    Posts
    1,596
    Mentioned
    49 Post(s)
    Tagged
    1 Thread(s)
    Quote Originally Posted by Rein_FOST View Post
    Thanks @LMStone510 .

    That makes sense yes, I actually did read about that tables somewhere when I was looking at something else.

    I was only worried because the car never did that. It would have just idled at 1200 at startup and drop to 800. This just started from last week so was a bit worried.

    Sent from my F8331 using Tapatalk
    Sorry; until XRJoe pointed it out I didn't realize you had a 225. I have no experience with tuning/mapping of that generation, so can't say for sure if what I offered earlier is correct for your car.

    I can say however that my car didn't start hunting until at least two years after I had it as I recall.

    All the best,
    Mark



    2013 Race Red ST1
    Who is "General Failure"? And why is he reading my hard disk??


  11. #10
    FST Member Rein_FOST's Avatar
    This user has no status.
     

    Join Date
    Jan 2017
    Posts
    12
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    No problem, and thanks for the input.

    Sent from my F8331 using Tapatalk

 

 
Page 1 of 2 1 2 LastLast

Sponsored Links

Posting Permissions

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

Similar Threads

  1. Funny idle on start up
    By HBGeek in forum Focus ST Discussions
    Replies: 4
    Last Post: 03-19-2016, 01:05 AM
  2. Rough Cold Idle
    By rtw07 in forum Focus ST Maintenance
    Replies: 14
    Last Post: 04-17-2015, 02:56 PM
  3. Stalling, hunting RPM and rough Idle repair list
    By Twheeler.stl in forum Focus ST Discussions
    Replies: 25
    Last Post: 08-13-2014, 09:49 AM
  4. Hunting Idle TSB? Ford says NO!
    By komsSTeed in forum Focus ST Performance
    Replies: 11
    Last Post: 01-26-2014, 02:37 PM
  5. Hunting idle, dying out
    By eddog216 in forum Focus ST Discussions
    Replies: 2
    Last Post: 11-03-2013, 05:13 PM
Find us on Google+