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Thread: My car/truck entered Reduced power mode, WHY!!!

  1. #1
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    My car/truck entered Reduced power mode, WHY!!!

    In MOST forced induction applications & in SOME NA applications some vehicles will experience this when the actual airflow exceeds the predicted airflow.

    Generally the fix is to go under the Engine Diagnostics tab & raise the P1514/P0068 table to its max.

    There have been some instances where the IFR/VE tables need to be tweaked as well, but these instances are very rare.
    It doesn't have to be perfect, it just needs to be done in two weeks...

    A wise man once said "google it"

  2. #2
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    hey lookie there i had this ?> a week or so ago and now here is my fix. thanks..now to go and see..

  3. #3
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    ok i just went to it, should i just multiply it buy like 3or 4 or is there a max value???

  4. #4
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    A few comments here. I believe this only affects the
    electric-throttle vehicles and it's a complaint about
    the alpha-N, throttle angle based airflow disagreeing
    the speed density airflow from what I make out. The
    fail-safe position is to not allow big throttle. Oh, fun.

    If you "fix" the code by opening up the maximum
    amount of disagreement, that disagreement is still
    there bugging its mind. Like a mental patient on
    their meds, yeah, OK, getting by.

    I don't know that we have any access to whatever
    alpha-N "stuff" the comparison is based on and it's
    likely you'd want to at least fix up the speed-
    density side back to realistic. But doing so, without
    the alpha-N gets schooled too, probably leaves some
    discrepancies and will need the error box widened.

  5. #5
    Senior Tuner Russ K's Avatar
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    Yes, the P1514/P0068 table affects ETC vehicles only. Just make sure that the g/cyl values are higher than your engine's g/cyl airflow.
    Multiply the whole table by 1.25 at a time until the values in the 100% TPS column are higher than your WOT scan data.

    Russ Kemp

  6. #6
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    Quote Originally Posted by Bill@HPTuners
    In MOST forced induction applications & in SOME NA applications some vehicles will experience this when the actual airflow exceeds the predicted airflow.

    Generally the fix is to go under the Engine Diagnostics tab & raise the P1514/P0068 table to its max.

    There have been some instances where the IFR/VE tables need to be tweaked as well, but these instances are very rare.


    rare occasion here

  7. #7
    Супер Модератор EC_Tune's Avatar
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    Yep,
    You have A LOT of airflow though Nick! LOL
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    Senior Tuner eficalibrator's Avatar
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    Quote Originally Posted by Bill@HPTuners
    Generally the fix is to go under the Engine Diagnostics tab & raise the P1514/P0068 table to its max.
    If I may correct you a bit, the solution should NOT be to simply max out the table. This is potentially dangerous since it completely eliminates the safety check!

    In reality, one should really just raise the values in this table to an amount slightly above the actual airflow at each cell (plus some small "fudge" margin) rather than completely max them out. This will prevent the failsafe code from setting during "normal" use, but still provide a safety net in case something legitimately goes wrong. Trust me, you WANT this safety check active.

  9. #9
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    Quote Originally Posted by eficalibrator
    If I may correct you a bit, the solution should NOT be to simply max out the table. This is potentially dangerous since it completely eliminates the safety check!

    In reality, one should really just raise the values in this table to an amount slightly above the actual airflow at each cell (plus some small "fudge" margin) rather than completely max them out. This will prevent the failsafe code from setting during "normal" use, but still provide a safety net in case something legitimately goes wrong. Trust me, you WANT this safety check active.
    Another rare occasion here!

    The safety check might be nice, but what if you have already maxed out the P1514 table and still are hitting the limit.

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    Quote Originally Posted by EC_Tune
    Yep,
    You have A LOT of airflow though Nick! LOL
    Nick can't get enough airflow-have you seen his combo? SICK!!!!
    GO RAIDERS!!!!!!!!!!

    02 C5 Z06
    8.8@160

  11. #11
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    Quote Originally Posted by eficalibrator
    If I may correct you a bit, the solution should NOT be to simply max out the table. This is potentially dangerous since it completely eliminates the safety check!

    In reality, one should really just raise the values in this table to an amount slightly above the actual airflow at each cell (plus some small "fudge" margin) rather than completely max them out. This will prevent the failsafe code from setting during "normal" use, but still provide a safety net in case something legitimately goes wrong. Trust me, you WANT this safety check active.
    Absolutely, whenever possible I would say learn how to create a histogram & a custom PID that would do this for you as that would be one of the better ways to do things.

    -Bill
    It doesn't have to be perfect, it just needs to be done in two weeks...

    A wise man once said "google it"

  12. #12
    Супер Модератор EC_Tune's Avatar
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    Quote Originally Posted by CrazyChris
    but what if you have already maxed out the P1514 table and still are hitting the limit.
    Look at your dynamic cylinder airflow. On the LS1 series, if you go over 2.32 g/cyl the P1514 sets regardless. You will have to fudge the VE & IFR to get the g/cyl below 2.32.
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    I've reduced my VE and IFR almost 60% and it's still doing it? But this time the max I saw was 2.11-WTF is going on? HELP!!!!!!!!!!!
    GO RAIDERS!!!!!!!!!!

    02 C5 Z06
    8.8@160

  14. #14
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    I occassionally have the issue that when it gets nailed, then cruised for a while and instantly nailed again that engine goes into reduced power mode and MIL comes on. Shutting engine off and restarting it and it goes away.

    would that be same category as above. It is a 12:1 compression, big cam 427 LS1 engine

  15. #15
    Супер Модератор EC_Tune's Avatar
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    Could be. Check your dynamic cylinder air. It could be injector settings, fuel pump issues, or a clogged fuel filter.
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  16. #16
    I've run into this issue with my Corvette. At first I wasn't able to get the car to move under any power until I scaled the entire table up 50%. After that, the car would go down the road fine until I got to 4000rpm in any gear. Then P1514 would return. I scaled >=4000 another 20% and was able to do the 1-2 shift at 4200rpm. The 2-3 set the code again. I scaled >=4000 another 10%. After that, I was able to turn any gear to 4000rpm or just above. This was all done a few nights ago.

    Today I was driving around and attempted to go to 5000rpm and beyond, but set the code at about 5200rpm. I scaled >=5000 another 10% and was then able to turn the motor to 6000rom without issue. Here is where I got confused.

    I've been tuning the car with the MAF enabled (wrong for VE, I know), so I decided that I would disable it. As soon as I disabled the MAF and the associated MIL codes that come along with it (P0100/P0101), I got P1514 again well under 2000rpm.

    Here are the questions I have:

    1. If the MAF is disabled, are any numbers in the Airflow vs. Frequency table going to matter at all? I assume not, but I'm not above asking the dumb/obvious question.

    2. It is common to set a P1514 code with the MAF disabled?

    3. Should one max out the P1514 table in Engine Diags while tuning with the MAF disabled?

    4. Should the P1514 table be scaled with the MAF disabled and not changed once the MAF has been re-enabled, or should it be rescaled after the VE tuning has taken place and the MAF re-enabled?

    Throttle body is a 95mm on a FAST 92 if that will help.

    Sorry for the long post and barrage of questions.

  17. #17
    Супер Модератор EC_Tune's Avatar
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    To answer the question you need to create a histogram that mimics the P1514 table. IF your dynamic cylinder air goes above the P1514 table anywhere, the P1514 code sets and you get "Reduced Engine Power".
    Fix the P1514 table FIRST. If you are still getting REP and dynamic cylinder air is above 2.32 g/cyl then you need to scale your IFR table down.
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  18. #18
    Quote Originally Posted by EC_Tune
    To answer the question you need to create a histogram that mimics the P1514 table. IF your dynamic cylinder air goes above the P1514 table anywhere, the P1514 code sets and you get "Reduced Engine Power".
    Fix the P1514 table FIRST. If you are still getting REP and dynamic cylinder air is above 2.32 g/cyl then you need to scale your IFR table down.
    Do I do this with the MAF enabled or disabled? I was able to set the code either way, but with the MAF disabled the happened far sooner than with it enabled.

    I would assume that I would want to set this table with the MAF enabled, since it's measuring airflow. If that's the case, what do I do if I disable the MAF and set the code again?

  19. #19
    So, I was dinking around with VCM scanner and a log that I had of me driving around after scaling the P1514 table up quite a bit.

    Here is what I did:

    Configured a Histogram with the Calculated Airflow vs. TPS vs. RPM table. For the sensor to monitor, I chose Cylinder Airmass in g/cyl. I then replayed my log and I'm getting decimal numbers that *seem* to make sense with the table in VCM editor. So here are my two questions:

    1. Should this table be scaled with the MAF enabled or disabled? If enabled, what does one do if the error returns when disabling the MAF to VE tune?

    2. Would it be a safe assumption that one could scale this table as high as possible, drive around logging, and then paste the numbers that appear in this histogram into the P1514 table and scale up by say 20% as a margin of error?

    ...perhaps, scale the table up as high as possible, disable the MAF then log and tune VE. Once completed, re-enable the MAF and paste the contents of the histogram into the P1514 table in editor and scale up 20% for margin of error.

    Thoughts/opinions? Have I lost my mind? Am I doing the typical noob thing and over thinking this too much?

  20. #20
    Супер Модератор EC_Tune's Avatar
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    You should be able to copy and paste the info into the P1514 but copy using the [+] values from the histogram as you are looking for max airflow values. Then I would probably add 10-15% for buffer space.
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