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Thread: Idle afr issues and knowledge needed

  1. #1
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    Idle afr issues and knowledge needed

    88 lancer 2.2 5 speed. Forged bottom end stock head, 2 piece intake, super 60 turbo,2.5" straight thru exhaust, 3bar map +40s on a socketed smec with ostrich.

    My issue is idle tuning mainly. I have many questions but mainly i need the car to idle richer ideally. At 14.7/15ish it idles rough and also pops here and there (not baro). I have tried adjusting the fuel from map baseline. I have messed with the pumping efficiency. But no matter what changes I make it seems as tho the computer will always revert back to the 14.7 afr. It idles way better at low 14afr to higher 13s with no popping or carrying on. The spark scatter seems to be varying the fuel/timing and raising the afr but it could also be other things I don't under or know about. I have been disconnecting the battery after every change to the tune as I'm told to clear the adaptives. Is this necessary? Do I need to change multiple tables to get the afr where I'd like it?

  2. #2
    Rhymes with tortoise. Turbo Mopar Staff cordes's Avatar
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    Re: Idle afr issues and knowledge needed

    You'll need to adjust the target idle AFR, or it will keep chasing the 14:7 fluctuation it's setup for. I've found that if I'm not within the window it can adjust for, then it will run horribly at low vac/idle until I get the fuel dialed in there. Either too rich or too lean will cause that in my experience, though it's always a case of my base cal being too lean after my modifications.

    Have you set the pumping efficiency table by comparing your anticipated AFR to the actual AFR by dragging the brakes and taking a reading once it settles down? Once you have that set right, you can adjust the fuel part throttle table. I really think you'll be chasing your tail by seeing that low of an AFR unless there is something up with your instrumentation.

    I've been working on this with my Lancer Shelby quite a bit this summer. I think I'm on my 6th or so revision and it's running very well now. My injectors don't flow exactly what the drop down in the injector scaling section suggested, so balancing the pumping table with the fuel baseline from map, and fuel part throttle tables has been a little more of a journey than in the past. I think what I have is super close, but we'll see the next time I drive the car.

  3. #3
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    Re: Idle afr issues and knowledge needed

    Quote Originally Posted by cordes View Post
    You'll need to adjust the target idle AFR, or it will keep chasing the 14:7 fluctuation it's setup for. I've found that if I'm not within the window it can adjust for, then it will run horribly at low vac/idle until I get the fuel dialed in there. Either too rich or too lean will cause that in my experience, though it's always a case of my base cal being too lean after my modifications.

    Have you set the pumping efficiency table by comparing your anticipated AFR to the actual AFR by dragging the brakes and taking a reading once it settles down? Once you have that set right, you can adjust the fuel part throttle table. I really think you'll be chasing your tail by seeing that low of an AFR unless there is something up with your instrumentation.

    I've been working on this with my Lancer Shelby quite a bit this summer. I think I'm on my 6th or so revision and it's running very well now. My injectors don't flow exactly what the drop down in the injector scaling section suggested, so balancing the pumping table with the fuel baseline from map, and fuel part throttle tables has been a little more of a journey than in the past. I think what I have is super close, but we'll see the next time I drive the car.
    How and where is the target afr adjusted? I have done a ton of pulls with the car under boost and adjusted the pumping efficiency till it was rock solid 11.5.

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    Rhymes with tortoise. Turbo Mopar Staff cordes's Avatar
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    Re: Idle afr issues and knowledge needed

    Pretty sure that's the O2 controller stuff. There was some discussion years ago in which I seem to remember Frank and Bucar making the oscillation smaller so that it was right at a target AFR while in part throttle. That was a decade or more ago I bet. I'm sure it's been discussed since, and I think there is an outline for how everything works in the .asm file comments. It's been a long time since I looked into any of this though.

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    Re: Idle afr issues and knowledge needed

    Quote Originally Posted by cordes View Post
    Pretty sure that's the O2 controller stuff. There was some discussion years ago in which I seem to remember Frank and Bucar making the oscillation smaller so that it was right at a target AFR while in part throttle. That was a decade or more ago I bet. I'm sure it's been discussed since, and I think there is an outline for how everything works in the .asm file comments. It's been a long time since I looked into any of this though.
    Where are the asm file comments your referencing?

  6. #6
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    Re: Idle afr issues and knowledge needed

    Quote Originally Posted by bgbmxer View Post
    Where are the asm file comments your referencing?
    It's in with all the folder you downloaded with the cal files. It'll be the .asm file which you can open with a text program. I looked in there on TSMEC, but couldn't seem to find the format for everything like I remembered. However, that seems to be the primary and secondary ramps section of MPTune. I would try a search on here to see if you can track down the older discussions regarding this.

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    Re: Idle afr issues and knowledge needed

    Yea reading everything I can but I'm over my head on alot of it. I don't know what to adjust on the 02 controller to richen it up slightly. Adjusting the pumping efficiency didn't make a difference. Adjusting the basefuel from map does but then at a certain point it goes off the deep end

  8. #8
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    Re: Idle afr issues and knowledge needed

    Yea reading everything I can but I'm over my head on alot of it. I don't know what to adjust on the 02 controller to richen it up slightly. Adjusting the pumping efficiency didn't make a difference. Adjusting the basefuel from map does but then at a certain point it goes off the deep end.

    - - - Updated - - -

    And my searching on here didn't produce anything that explains what to change on the 02 controller in which to richen idle up. Maybe I'm doing something wrong who knows

  9. #9
    Rhymes with tortoise. Turbo Mopar Staff cordes's Avatar
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    Re: Idle afr issues and knowledge needed

    I generally search with google and do the "site:turbo-mopar.com" thing at the end. It is much better than the site's search engine.

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