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Thread: Unusual idle occurance after injector replacement/IFR adjustment

  1. #1
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    Default Unusual idle occurance after injector replacement/IFR adjustment

    I went ahead and installed a set of injectors I purchased a while back, Accel 42# units as I recall, and after adjusting the IFR to match I've been able to get the car running, however I have the strangest of occurances when the car first starts. For the first 3-5 seconds my LC1 is reporting normal AFR levels (14.6-15.0), but the engine then immediatley changes tone and begins to chop very heavily, almost to the point of stalling and all the while the LC1 begins to report excessivley high AFR levels of 20+!! This will last for approx. 45-60 seconds with no input from me after which the engine magically "snaps out of it" and resumes a normal idle tone and the LC1 immediatley richens up to normal levels. Now i'm not 100% sure on the accuracy of the LC1's readings during the abnormal phase simply because of the heavy lope/reversion and it's possible effects on the numbers but there is no doubt something fishy is going on here.

    I'm attatching my current map in the hopes somebody might catch on to something I've overlooked in my quest to bring my car back to 'normal' since the injector swap, any help or input is much appriciated
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  2. #2
    Lifetime Member hquick's Avatar
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    MIne does the same with the SVO 42's. Doesn't go particularly choppy but does the sudden lean swing thing and then back to commanded after about a minute or so.
    Howard

    YOU ONLY NEED TWO TOOLS IN LIFE - WD-40 AND DUCT TAPE. IF IT DOESN'T
    MOVE AND SHOULD, USE THE WD-40. IF IT SHOULDN'T MOVE AND DOES, USE THE
    DUCT TAPE.
    IF YOU CAN'T FIX IT WITH A HAMMER, YOU'VE GOT AN ELECTRICAL PROBLEM.


    98 K1500 'HOLDEN' Suburban.
    Custom Whipple SC, Mercruiser Marine intake, 0411 PCM, 4L80E w/shift kit

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    Dumb question maybe, but isn't your air pump giving you the high afr reading while it cycles during initial start up?
    2000 Camaro SS Convertible
    M6,
    LTs, AFR 205s, Comp xer 220/224, LS6 intake, Ported TB, AR TT IIs

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    No air, no egr, no cats.. very perplexing, especially since it was just fine on the previous set of squirters. I'm even contemplating swaping out my old injectors and going back to the previous tune just to see if I've developed some odd mechanical issue or if it's truly just a 'weird' case unhappy PCM.
    Dave
    -'07 Acura TL Type-S
    -'07 Honda Ridgeline RTS
    -'00 Pontiac Trans Am WS6

  5. #5
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    Ok I just performed a dead cold start up with the scanner running. I'm going to attatch the log so everybody can take a look but after reviewing it here's what I see. As soon as the engine comes to life it momentarily idles at a normal AFR, at this point I was logging idle properties of approx. 75-78kpa, 25*C ECT and idle speed of approx. 600-620 rpm, than suddenly you see the AFR rocket up to 20+ with the kpa, ECT and rpm remaining basically unchanged.... baffling!! Something is causing the PCM to pull a tremendous amount of fuel for about 45-60 seconds before giving it right back and the car goes back to idling normal. If nothing esle I certainly hope I can pique some curiosity out there

    BTW although my vision is getting blurry from the hours spent pouring over the info in here, its amazing what I'v picked up in just a few hours, good stuff in here guys!
    Attached Files Attached Files
    Dave
    -'07 Acura TL Type-S
    -'07 Honda Ridgeline RTS
    -'00 Pontiac Trans Am WS6

  6. #6
    Lifetime Member jfpilla's Avatar
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    While you're in open loop actual AFR is not tracking Commanded B3605. When it goes to closed loop Stoich is taking over.
    Suggest you look at the VE's. VE's being off is usually what causes AFR to not track in open loop.
    2003 red vert
    Mods:
    LS7 crate engine, wet sump, 24xx reluctor
    LPE 100mm MAF
    Vararam, cold air intake and bridge
    RPM Level 6/4L60e trans
    3.42 gears
    Yank SS3600
    1-7/8" AR headers
    Z06 exhaust
    470rwhp 437rwtq
    1/8th mi-1.526-60'-6.862-1/8th-@100.74mph

  7. #7
    Lifetime Member hquick's Avatar
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    Hi Jf,
    Mine does the same but I'm running OLSD???
    Howard

    YOU ONLY NEED TWO TOOLS IN LIFE - WD-40 AND DUCT TAPE. IF IT DOESN'T
    MOVE AND SHOULD, USE THE WD-40. IF IT SHOULDN'T MOVE AND DOES, USE THE
    DUCT TAPE.
    IF YOU CAN'T FIX IT WITH A HAMMER, YOU'VE GOT AN ELECTRICAL PROBLEM.


    98 K1500 'HOLDEN' Suburban.
    Custom Whipple SC, Mercruiser Marine intake, 0411 PCM, 4L80E w/shift kit

  8. #8
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    Quote Originally Posted by jfpilla View Post
    While you're in open loop actual AFR is not tracking Commanded B3605. When it goes to closed loop Stoich is taking over.
    Suggest you look at the VE's. VE's being off is usually what causes AFR to not track in open loop.
    Question in regards to this, according to B4201 the engine determines to run the 'cold temp timer' if it's less than that particular value (9*C in my case), then according to B4203 it'll run the 'normal engine temp' timer if it's over 75*C, but what happens in between? From what I can see these timers dictate when the PCM can enable CL yet I don't see a value for temps between 'cold' and 'normal'? And as a side note, if I were to enable B4206 'Enable O2 with open loop commanded fuel', then the O2's could assist the PCM in maintaining proper AFR even if my VE's are somewhat askew yes?
    Dave
    -'07 Acura TL Type-S
    -'07 Honda Ridgeline RTS
    -'00 Pontiac Trans Am WS6

  9. #9
    Lifetime Member jfpilla's Avatar
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    Quote Originally Posted by VTC_WS6 View Post
    Question in regards to this, according to B4201 the engine determines to run the 'cold temp timer' if it's less than that particular value (9*C in my case), then according to B4203 it'll run the 'normal engine temp' timer if it's over 75*C, but what happens in between?
    xxxxxxYou should be looking at B4205.

    From what I can see these timers dictate when the PCM can enable CL yet I don't see a value for temps between 'cold' and 'normal'?
    xxxxxxSee B3605.

    And as a side note, if I were to enable B4206 'Enable O2 with open loop commanded fuel', then the O2's could assist the PCM in maintaining proper AFR even if my VE's are somewhat askew yes?
    xxxxxxYou have a wideband, tune it properly. VEs have an impact under
    4000rpms in assisting fueling when the maf can't handle it.
    2003 red vert
    Mods:
    LS7 crate engine, wet sump, 24xx reluctor
    LPE 100mm MAF
    Vararam, cold air intake and bridge
    RPM Level 6/4L60e trans
    3.42 gears
    Yank SS3600
    1-7/8" AR headers
    Z06 exhaust
    470rwhp 437rwtq
    1/8th mi-1.526-60'-6.862-1/8th-@100.74mph

  10. #10
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    Sorry to hijack, but i have a noob question.
    Why is your MAP pressure so high at idle? My logs show around 55-60 KPa at Idle for my car. What would cause this difference?

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