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Thread: cold idle hunting (goes crazy lean) & iat rwads 102º on scan tool all the time.

  1. #1
    Mitsu booster
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    cold idle hunting (goes crazy lean) & iat rwads 102º on scan tool all the time.

    My car is an 86 glh omni. I converted to t2 blow through recently. Alk parts were off a 89 Shelby z daytona. Im using mptune & GLHS 2 calibration from boostbutton. Getting it ironed out except for 1st start of the day. Pops rite off goes into normal fast idle. After about 10sec wideband goes off chart lean it about dies. Then catches up wideband goes rich. It does this crazy lean/rich dance for about 30 seconds or so then all is well. How do I go about curing this one? Also I noticed using my solous pro snap-on scanner iat sensor reads 2.50v & 102º all the time. I unplug it stays the same but engine idle is effected & then drops a code. Any help id appreciate!

  2. #2
    Boost, it's what's for dinner... Turbo Mopar Staff Aries_Turbo's Avatar
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    Re: cold idle hunting (goes crazy lean) & iat rwads 102º on scan tool all the time.

    dunno about the solus but is the wideband feeding the LM simulated narrowband signal? this has been a recipe for disaster in my experience.

    leave the wideband as monitoring only and let a stock o2 feed the ECU with its signal.

    Brian

    Quote Originally Posted by turbovanman
    This one is easy, I have myself to blame, I rush things, don't pay attention to gauges when I should, change to much stuff at once then expect miracles, the list is endless.

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    Rhymes with tortoise. Turbo Mopar Staff cordes's Avatar
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    Re: cold idle hunting (goes crazy lean) & iat rwads 102º on scan tool all the time.

    Quote Originally Posted by Aries_Turbo View Post
    dunno about the solus but is the wideband feeding the LM simulated narrowband signal? this has been a recipe for disaster in my experience.

    leave the wideband as monitoring only and let a stock o2 feed the ECU with its signal.

    Brian
    FWIW, I've used multiple brands of WBO2 and the NBO has run very well for me. I have the sensor in the stock location and I use a battery ground for the unit.

  4. #4
    Boost, it's what's for dinner... Turbo Mopar Staff Aries_Turbo's Avatar
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    Re: cold idle hunting (goes crazy lean) & iat rwads 102º on scan tool all the time.

    Quote Originally Posted by cordes View Post
    FWIW, I've used multiple brands of WBO2 and the NBO has run very well for me. I have the sensor in the stock location and I use a battery ground for the unit.
    what was the setup though. i grounded the unit at the battery and mine has a differential ground/signal out. i had the LM sensor ground (black/blue stripe) tied into the wideband sensor signal ground and the signal to the o2 wire at the LM. 2.5L turbonator LM cal, wander central lol. use a stock o2 and it was pretty good idle.

    the only cal that had a good idle on my LM setup with the wideband feeding the o2 to the LM was an old relentless performance cal on 3-bar +40's. the pumping efficiency table was initially incorrect for that cal (i corrected it later) but even with a 2.2L pumping efficiency table and 2.5L map fuel tables, it had a solid idle. it was just a little lean at idle and rich into higher rpms.

    Brian

    Quote Originally Posted by turbovanman
    This one is easy, I have myself to blame, I rush things, don't pay attention to gauges when I should, change to much stuff at once then expect miracles, the list is endless.

  5. #5
    Mitsu booster
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    Re: cold idle hunting (goes crazy lean) & iat rwads 102º on scan tool all the time.

    Nope the wide band is just for me to keep an eye on afr. Using 4 wire n/b 02 sensor in stock location just for the computer. Wideband is in no control of anything.

    - - - Updated - - -

    Nope the wide band is just for me to keep an eye on afr. Using 4 wire n/b 02 sensor in stock location just for the computer. Wideband is in no control of anything.

  6. #6
    Mitsu booster
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    Re: cold idle hunting (goes crazy lean) & iat rwads 102º on scan tool all the time.

    Im not sure what table to begin adjusting. Id heard may coldtableC? I moved the start point up a little bit? Made no difference this morning at all. Pops rite of goes to almost 2k fast idle. Starts to settle down at 1200. Then after about 10-15 seconds can watch afr tank into lean territory & then the severe surging for about 30-45 seconds. Then it gets control of itself again & stays about 14.2-14.7 normal 900 rpm ilde from then on. No hotstart Iissues at all. If I fire it up and don't let it warm up at all & just go stright into gear & start driving. Id never know I had an issue. But I don't just jump in and go.

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    Supporting Member II Turbo Mopar Contributor Shadow's Avatar
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    Re: cold idle hunting (goes crazy lean) & iat rwads 102º on scan tool all the time.

    Sounds like fueling in that spot and while transitioning from cold start to o2 controlled idle is off more than the ECU is capable of controlling smoothly.

    Try unplugging 4 wire o2 and cold start it watching wideband and logging rpm and temp. This will tell you how lean or rich it's going at that spot without o2 correction and you will know what the o2 is trying to correct, a lean or rich condition.

    Once you have figured that out you can adjust the appropriate rpm/temp/ table and fine tune it without o2 feedback till its very close.

    Then plug the o2 back in.

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  8. #8
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    Re: cold idle hunting (goes crazy lean) & iat rwads 102º on scan tool all the time.

    According to wideband its going way lean.

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    Rhymes with tortoise. Turbo Mopar Staff cordes's Avatar
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    Re: cold idle hunting (goes crazy lean) & iat rwads 102º on scan tool all the time.

    Quote Originally Posted by Aries_Turbo View Post
    what was the setup though. i grounded the unit at the battery and mine has a differential ground/signal out. i had the LM sensor ground (black/blue stripe) tied into the wideband sensor signal ground and the signal to the o2 wire at the LM. 2.5L turbonator LM cal, wander central lol. use a stock o2 and it was pretty good idle.

    the only cal that had a good idle on my LM setup with the wideband feeding the o2 to the LM was an old relentless performance cal on 3-bar +40's. the pumping efficiency table was initially incorrect for that cal (i corrected it later) but even with a 2.2L pumping efficiency table and 2.5L map fuel tables, it had a solid idle. it was just a little lean at idle and rich into higher rpms.

    Brian
    I had an old PLX unit in my black omni with D-cal, and Chem based stuff. I had my CSX running well with a newer PLX unit and MP Tune. The omni was an LM and the CSX was a SBEC.

  10. #10
    Visit www.boostbutton.com... Turbo Mopar Contributor ShelGame's Avatar
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    Re: cold idle hunting (goes crazy lean) & iat rwads 102º on scan tool all the time.

    There was an issue with my early GLHS code that I think did what you describe (I don't remember for sure, but it was an idle issue).

    You should update it to the latest .asm - https://drive.google.com/drive/folde...loxSlFUajd5NUE

    I'd offer to do it for you, but I don't do cals anymore, and I don't have any of the equipment anymore.

    What is your name? I can post your cal files for you. It just needs to be re-compiled with the latest .asm and re-burned to the chip(s).

    EDIT: Eh, maybe not. The issue I had with T-GLHS was related to transient fuel. Still, lemme know your name - I can check your cal to see if it had that issue or not...
    https://db.tt/SV7ONZpQ
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  11. #11
    Mitsu booster
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    Re: cold idle hunting (goes crazy lean) & iat rwads 102º on scan tool all the time.

    Phil Fleming. I can p.m. you my email address?

  12. #12
    Mitsu booster
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    Re: cold idle hunting (goes crazy lean) & iat rwads 102º on scan tool all the time.

    I downloaded mptune & the 86-87 GLHS stage 2 zip flies rite fromt the boostbutton wiki page if that helps at all about 2-3 weeks ago. I sent you a mgs (I think I did anyway)

  13. #13
    Mitsu booster
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    Re: cold idle hunting (goes crazy lean) & iat rwads 102º on scan tool all the time.

    Ive confirmed the ect sensor is reading correctly. The only thing ive noticed that soon as it fires it runs good for about 10-15 seconds after that is goes off chart lean & surges like mad and sometimes dies. It does this until on (my scanner) until 90º-100º then comes out of it and runs normal afterwards. The only other bit of info I can give is the iat sensor no matter the temp always reads 102º & 2.50v. Never changes on my scanner. But no codes. & logic module is sending out 5v & back probing if running it does vary. So im not sure if its just giving my scanner false info or not. Any help would be great!

  14. #14
    boostaholic
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    Re: cold idle hunting (goes crazy lean) & iat rwads 102º on scan tool all the time.

    My car was doing exactly the same thing when I was running an LM.

    Do you have a spare IAT, or a bunch of resistors laying around? I'd be interested to see if changing the IAT sensor value had any effect.

  15. #15
    Mitsu booster
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    Re: cold idle hunting (goes crazy lean) & iat rwads 102º on scan tool all the time.

    I have 2 known & working resistance wise I.a.t. sensors. Ive tried them both same results. I can unplug I.a.t. while running & still never moves.

  16. #16
    boostaholic
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    Re: cold idle hunting (goes crazy lean) & iat rwads 102º on scan tool all the time.

    Have you checked the pins at the LM connector? They do get corroded and crushed, make poor contact, and make the ecu do odd things.

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    Moderator Turbo Mopar Staff Force Fed Mopar's Avatar
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    Re: cold idle hunting (goes crazy lean) & iat rwads 102º on scan tool all the time.

    LM's seem to be having issues left and right lately...
    Rob M.
    '89 Turbo GTC

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  18. #18
    Boost, it's what's for dinner... Turbo Mopar Staff Aries_Turbo's Avatar
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    Re: cold idle hunting (goes crazy lean) & iat rwads 102º on scan tool all the time.

    Quote Originally Posted by Force Fed Mopar View Post
    LM's seem to be having issues left and right lately...
    i wonder if its bad electrolytic caps...... has happened to the jeep and dsm guys.

    http://www.jeepforum.com/forum/f12/c...rs-ecu-492597/

    brian

    Quote Originally Posted by turbovanman
    This one is easy, I have myself to blame, I rush things, don't pay attention to gauges when I should, change to much stuff at once then expect miracles, the list is endless.

  19. #19
    Mitsu booster
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    Re: cold idle hunting (goes crazy lean) & iat rwads 102º on scan tool all the time.

    The l.M. im using is the stock one that was in my 86 lebaron GTS 2.2turbo1 automatic. I de soldered the the upper & lower chips. Then socketed them both. That l.m. worked just fine then I swapped in a fwd calibration & its been setting on a shelf ever since. Idk if its in the calibration or a setting in the calibration thats off a bit. But id sure love to get it fixed! As this will be a real nuisance when the weather starts getting colder!

  20. #20
    boostaholic
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    Re: cold idle hunting (goes crazy lean) & iat rwads 102º on scan tool all the time.

    Could be. The newest LM is at least 30 now. Should be easy enough to replace them all.

    Quote Originally Posted by Aries_Turbo View Post
    i wonder if its bad electrolytic caps...... has happened to the jeep and dsm guys.

    http://www.jeepforum.com/forum/f12/c...rs-ecu-492597/

    brian

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