PE addder vs IAT
08-23-2015, 05:58 PM
#1
PE addder vs IAT Can someone tell me how this table works? Does a positive number add fuel to that segment. I am running olsd and want to richen the car up at lower IAT.I bracket race the car and I am trying to stop it from speeding up as it cools down. I am thinking if I add some fuel as it cools down this will accomplish what I am after.
08-27-2015, 01:45 PM
#2
The PE adder vs IAT is there to keep AFR consistent throughout IAT changes. As IAT increases, the car will get richer as the air is thinner and the same amount of fuel is added. The PE Adder vs IAT reduces fueling at higher temps and increases fueling at lower temps. Should be noted that all of the stock files I just looked at had this table zeroed out. Anyway, it functions by adding to the PE multiplier. As in, if your PE multiplier is 1.17 and you want the cooler temps to be even richer, you would put in .05 and your PE would be 1.22.
08-27-2015, 02:57 PM
#3
The PE adder vs IAT is there to keep AFR consistent throughout IAT changes. As IAT increases, the car will get richer as the air is thinner and the same amount of fuel is added. The PE Adder vs IAT reduces fueling at higher temps and increases fueling at lower temps. Should be noted that all of the stock files I just looked at had this table zeroed out. Anyway, it functions by adding to the PE multiplier. As in, if your PE multiplier is 1.17 and you want the cooler temps to be even richer, you would put in .05 and your PE would be 1.22.
08-27-2015, 09:33 PM
#4
Hence why I added the note that said most every configuration I checked in my library has it zeroed out. This includes my own tune. I imagine it might be useful to those with SD tunes and/or open-loop tunes that don't have fuel trims to take up the slack or the MAF to compensate for intake charge density changes. Remember, not everyone runs o2 sensors or MAFs....I ALMOST used this table once when I was running OLSD.
08-27-2015, 09:59 PM
#5
Hence why I added the note that said most every configuration I checked in my library has it zeroed out. This includes my own tune. I imagine it might be useful to those with SD tunes and/or open-loop tunes that don't have fuel trims to take up the slack or the MAF to compensate for intake charge density changes. Remember, not everyone runs o2 sensors or MAFs....I ALMOST used this table once when I was running OLSD.
08-27-2015, 10:55 PM
#6
Hey man, it's there for you to use it if you want. If this guy wants to experiment with it to compensate for tiny variables at the track he should go ahead and do it. It's actually a very useful but rarely used and over-looked table. Many forced induction guys find it's the only way to cure heat-soak induced lean conditions. More than one way to skin a cat, and just because it's not your way that doesn't mean it's a bandaid or a poor tune.
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08-28-2015, 04:56 AM
#8
I am looking to use it to keep my car within .001 of a second between runs. We start racing in the afternoon and race into the night. My car barely swings .05 all day long but sometimes that is not good enough. My car is olsd Car runs fine (11,50 cam only) but I am looking to use the table for a very specific purpose. If you understand bracket racing you will understand what I am trying to achieve .I want 11.50 in the sun at 88 degrees and I want 11.50 in 65 degree in the dark. Thanks for the responses. Might experiment some tonight just needed a place to start.
08-28-2015, 11:39 AM
#11
I am looking to use it to keep my car within .001 of a second between runs. We start racing in the afternoon and race into the night. My car barely swings .05 all day long but sometimes that is not good enough. My car is olsd Car runs fine (11,50 cam only) but I am looking to use the table for a very specific purpose. If you understand bracket racing you will understand what I am trying to achieve .I want 11.50 in the sun at 88 degrees and I want 11.50 in 65 degree in the dark. Thanks for the responses. Might experiment some tonight just needed a place to start.
How was the car tuned, on a dyno or all at the track?
08-28-2015, 02:32 PM
#13
What year model or OS? I just checked 99-07 and they all had it zeroed out except one had some number for IAT being 248+. I just randomly opened a 5.3 or 6.0 truck tune from each year when I looked. Since there are multiple OS for some years I could have not just opened the correct OS that used that table.
08-28-2015, 03:09 PM
#14
Found an interesting quote over on HP Tuners forum that claims that this table only exists because Holden requested it and then they never used it. Sounds like orphaned engineering. Not surprised though that you might find it used in some truck tunes. Trucks seemed to like to use a lot of tables for whatever reason. Spreading out variables? Redundancy? Compartmentalized programming? I started with a truck computer...the amount of crap that was deleted is amazing!
08-28-2015, 04:11 PM
#15
What year model or OS? I just checked 99-07 and they all had it zeroed out except one had some number for IAT being 248+. I just randomly opened a 5.3 or 6.0 truck tune from each year when I looked. Since there are multiple OS for some years I could have not just opened the correct OS that used that table.
08-28-2015, 09:14 PM
#16
I like the table for meth injection.
08-28-2015, 11:05 PM
#17
Moderator
A standard formula will calculate how air density changes with temperature. I'm pretty sure this formula is built into every PCM/ECM so that it can properly fuel the engine at different intake air temperatures. Therefore this table is normally zero as the built-in formula calculates the fueling correctly.
I too can think of various "special" reasons for using that table to tweak the formula, but would be about the last thing I fiddle with.
I too can think of various "special" reasons for using that table to tweak the formula, but would be about the last thing I fiddle with.
Last edited by mrvedit; 08-29-2015 at 08:29 AM. Reason: Clarify sentence
08-29-2015, 12:22 AM
#18
a standard formula will calculate how air density changes with temperature. I'm pretty sure this formula is built into every pcm/ecm so that it can properly fuel the engine at different intake air temperatures. Therefore this table is normally zero as the built-in formula calculates the fueling correctly.
I can think of various "special" reasons for using it too, but would be about the last thing i fiddle with.
I can think of various "special" reasons for using it too, but would be about the last thing i fiddle with.
08-29-2015, 12:05 PM
#20
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One important question is the IAT's real fidelity. Staging
lane heat soak on the sensor has nothing at all to do
with the big-end in-taken air temp. Do you, or don't you,
really want to respond to recent history (as opposed to
putting the IAT out of the engine bay and ducting the
intake air such that its temperature equals, close enough,
the outside air temp)?
lane heat soak on the sensor has nothing at all to do
with the big-end in-taken air temp. Do you, or don't you,
really want to respond to recent history (as opposed to
putting the IAT out of the engine bay and ducting the
intake air such that its temperature equals, close enough,
the outside air temp)?
