I lower "IFR" by 2% , did this make PE WOT go up 2% or ??
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Ok, I lowered my "IRF", [injector tables], by 2% to get my LTFT to go negative numbers across the board.
By lowering the "IRF" tables by 2% ,the PCM thinks the injectors are smaller, so PCM commands them on longer, making my LTFT to all go into the negative numbers, because I'm running richer. It works well, I understand this....
But, what is this doing to my WOT PE ???
Did I just go richer by 2% WOT ,because I made the injectors look smaller to the PCM ??
If so, did I cause a "ripple" effect on other parts of the PCM causing other areas to go richer or leaner ???
Thanks,
Dave
By lowering the "IRF" tables by 2% ,the PCM thinks the injectors are smaller, so PCM commands them on longer, making my LTFT to all go into the negative numbers, because I'm running richer. It works well, I understand this....
But, what is this doing to my WOT PE ???
Did I just go richer by 2% WOT ,because I made the injectors look smaller to the PCM ??
If so, did I cause a "ripple" effect on other parts of the PCM causing other areas to go richer or leaner ???
Thanks,
Dave
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Would I changed the whole table? Or just the first column?
joel(Bink)
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#7
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Yes the pe will be richer.
joel
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Yes the pe will be richer.
joel
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Let's assume positive LTFTs directly scale WOT fueling up.
If enrichment based on originally positive LTFTs would be in the same scale as the effect of injector offset scaling at WOT then the WOT fueling would remain the same in case you succeeded dialing LTRIMs to exactly zero. They will be negative though and that means you have scaled IFR in a way that WOT will be richer as IFR is in the equation when calculating WOT fueling. So this applies if we believe the effect of LTFT caused enrichment and IFR scaling is at the same scale.
Though, I've seen some arguments against the negative LTFT theory. At least I wouldn't count on IFR scaling not affecting the WOT fueling or it becoming leaner due to LTFTs not being added on top of PE. By default I would say WOT fueling will be richer if you scale IFR down.
If enrichment based on originally positive LTFTs would be in the same scale as the effect of injector offset scaling at WOT then the WOT fueling would remain the same in case you succeeded dialing LTRIMs to exactly zero. They will be negative though and that means you have scaled IFR in a way that WOT will be richer as IFR is in the equation when calculating WOT fueling. So this applies if we believe the effect of LTFT caused enrichment and IFR scaling is at the same scale.
Though, I've seen some arguments against the negative LTFT theory. At least I wouldn't count on IFR scaling not affecting the WOT fueling or it becoming leaner due to LTFTs not being added on top of PE. By default I would say WOT fueling will be richer if you scale IFR down.
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By default I would say WOT fueling will be richer if you scale IFR down.
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Yes the pe will be richer.
joel
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So should you scale down PE, when scaling down IFR? In the attempt to lower LTFT's?
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Ok you guys are really confusing me now. ![Driving](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_driving3.gif)
Leave positive LTFTs out of the picture...![Happy](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_stretch.gif)
Let's say that you where already negative on LTFT & decreased "IRF" by 2%... would you be 2% richer at PE WOT ???
I say yes, because I told the PCM that I have smaller injectors by 2%, so the PCM is increasing the injector flow by 2%...
Thanks,
Dave
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Leave positive LTFTs out of the picture...
![Happy](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_stretch.gif)
Let's say that you where already negative on LTFT & decreased "IRF" by 2%... would you be 2% richer at PE WOT ???
I say yes, because I told the PCM that I have smaller injectors by 2%, so the PCM is increasing the injector flow by 2%...
Thanks,
Dave
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Ok, you got me to second guess myself now. After muling it over I've concluded that wot will richen up once your ltrims go below 0, not above. Let's say you're at 0 cruise and 0 wot. You will get xx:1 afr. Now if you drop the table enough to change the ltrims to -5 at cruise, they will still go to 0 at wot, but that part of the ifr table is now ~5% richer. The pe will still add the same amount as before, so you'll get a richer afr. If ltrims are positive, then changing the table will keep wot fueling the same, until the ltrims get under 0.
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I would say yes as well but I would not count on scaling both PE and IFR tables by the same factor will keep WOT fueling unchanged.
Or leave everything alone and tune WOT only with PE?
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The way you are supposed to do it is first adjust IFRs until your LTFTs stay slightly negative all the time. Then, adjust PE vs. RPM until you get 890mv's on the O2s. If you do it any other way, it will be very difficult because what ever the LTFTs are just before you went to WOT will be added in. I believe this information is pretty good because it came from someone at GM.
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originally posted by Cal: The way you are supposed to do it is first adjust IFRs until your LTFTs stay slightly negative all the time. Then, adjust PE vs. RPM until you get 890mv's on the O2s
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