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Thread: MAF'd Power Enrichment less than 100% TPS

  1. #1
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    Default MAF'd Power Enrichment less than 100% TPS

    I am having a few issues with Power Enrichment and less than 100%TPS on a MAF'd car. I tend to get on the lean and I can't fix this w/o damaging the 100%TPS zone of the MAF....

    Anyway around this???


    I have tried the settings in the dynamic section, but thus far they do nothing.... and honestly... truck starts to ping when this is happening...

    One more thing.. depending on RPM these MAF Hz will overlap each other so.. if i "fix" the maf on it, I will have issues when in 100% and if I change the PE table, same thing.... Ideas?
    "All that is needed for the triumph of evil is that good men do nothing..."

  2. #2
    Lifetime Member swingtan's Avatar
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    Highlander, it's probably worth posting up your current tune and the log file.

    Looking at the image there appears to be 2 issues....

    1. Excessive Dynamic Fueling: This is evident in the large "rich" spike at the beginning of the PE sections and to a lesser extent at the ends when the throttle is shut. Remember, that dynamic fueling will only come into effect when there is rapid throttle movements.
    2. The VVE / MAF calibration is out, causing the measured WB AFR to go from rich to lean in the image shown. Depending on the tune, the ECM will blend the MAF and VVE settings to get airflow figures and then over a set RPM, use the MAF exclusively ( normally 4000 RPM ).


    Without seeing the tune or having a good look at the log file, I'd return the dynamics back to std and then dial in both the VVE and the MAF to get the AFR's correct for steady throttle states. Then I'd look at the transients to see if anything is needed. Normally if the MAF is turned on, there shouldn't be a great need to change the dynamics too much ( unless there have been other significant changes ).

    Does this make sense?

    Simon.

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    As soon as I get a break I'll post the tune, but for now... Although you are right that the MAF and VVEs are not to the T, nor close on this tune, I do get this issue with the other boosted application I am working with which is to T on BOTH and still get the same issue. On that other one the Dynamic fueling is stock.
    Even still.. wouldn't it stay rich if the dynamic fueling is too high???

    What do you call to low the dynamic fueling?? Stock numbers?

    Thanks man!!!
    "All that is needed for the triumph of evil is that good men do nothing..."

  4. #4
    Lifetime Member swingtan's Avatar
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    For dynamics, enrichment will only occur while the throttle is moving rapidly. One the rate of change drops below a certain level or the throttle is stationary, the additional fuel being added is removed and you are left with the normal commanded fuel. The amount of time that the "dynamic" fuel can effect the final commanded fuel is quite small, maybe only up to 250mS or so. You can adjust the "ramp out" values to extend the dynamic fueling slightly, but not by much.

    Remember that the dynamics / transient fueling, works like a pump jet in a carby. Once you've stomped on the pedal, the available fuel in the pump is gone until you release the pedal.

    Simon.

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    Issue is solved....

    Mayor impact was changing the multiplier tables above 120kpa where it was happening. Both tables made a fuel evaporation and stomp mass....
    "All that is needed for the triumph of evil is that good men do nothing..."

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    Lifetime Member swingtan's Avatar
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    Good work Highlander.

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    Well... I want to update this topic...

    This seems to happen on EVERY SINGLE E38 I am tuning... and for the life of me I have to change different tables to get things under control.

    On the last Z06 I tuned this thing happened and the only thing I did to change it was to change the impact factor at 0%. Now, on the truck this changed with a different table, although it was using an E67 on the 5cyl colorado, but similar codes I believe.

    Now this is an ongoing issue that could lead to potential failures given track racing and the such. Now. Since the factory puts these engines super rich 2 points leaner doesn't matter... but when you start getting to the 12:1 afr range... 2 pt leaner will knock and could slowly kill the engine, SPECIALLY on boosted applications.

    at first my main concern was the lean spike... but now, I want both lean and rich spikes to go away.

    Any thoughts on the matter?

    BTW... VVE has little to no effect on this issue.

    Thank you
    "All that is needed for the triumph of evil is that good men do nothing..."

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