Where do open loop fuel trims come from?
Where do open loop fuel trims come from? When you first start your car where do the ftc 20 trims come from? Is it simply the cell 18 fuel trims from the previous run time?
Also where do the ftc 22 trims come from? After looking carefully at my logs, it seems that it doesn't usually take the trims from the cell right before going wot. I've seen ftc 15 with trims of 0% and when I go into ftc 22 they're magically 0.8%.
Also I've seen weird stuff like cell 20 trims changing after startup. A couple times I've even seen cell 22 trims change gradually. I thought fuel trims weren't supposed to learn in open loop. Can somebody who has actually looked at the code explain what all goes into open loop fuel trims?
Also where do the ftc 22 trims come from? After looking carefully at my logs, it seems that it doesn't usually take the trims from the cell right before going wot. I've seen ftc 15 with trims of 0% and when I go into ftc 22 they're magically 0.8%.
Also I've seen weird stuff like cell 20 trims changing after startup. A couple times I've even seen cell 22 trims change gradually. I thought fuel trims weren't supposed to learn in open loop. Can somebody who has actually looked at the code explain what all goes into open loop fuel trims?
Yeah, your issue is what got me thinking about this, but i saw this stuff in my logs too. I'd look at your logs but I don't really know what to tell you unless I know where cell 20 and 22 trims come from. I hope magnus or gameover responds to this thread cause youd really have to look at the pcm code to know this for sure.
yeah, i was just saying if you wanted to see if it happened at the same times, but i reread it and thats when my car does it too. i dont know if the car enters open loop on start up for xx amount of time and uses cell 20 for that. and after started up for so long it will enter idle cell 19. when i log today from a cold start ill log my ftc to see waht happens
That really doesn't answer the question. I know (positive) trims are still added to open loop fueling, at least in PE. Are you saying trims aren't applied to any open loop, non pe fueling? And if what you're saying is true, why don't the fuel trims lock at 0 on cold starts? Also, i've seen my trims change in ftc 20 & 22.
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Verdad Gallardo i recieved this response in another post, FTC 20 cold idle, but my car was hot when i was in this cell, 80*c, this was after start up though.
Fuel Trim Group 1, Cells 0 - 3
• FTC 0 - 2 slight deceleration, little to no load
• FTC 3 low load, power enrichment
Fuel Trim Group 2, Cells 4 - 7
• FTC 4 low load, part throttle
• FTC 5 low load, part throttle
• FTC 6 moderate load, part throttle
• FTC 7 moderate load, part throttle, power enrichment
Fuel Trim Group 3, Cells 8 - 11
• FTC 8 - 10 moderate load, part throttle
• FTC 11 moderate load, part throttle, power enrichment
Fuel Trim Group 4, Cells 12 - 15
• FTC 12 - 14 higher load, power enrichment
• FTC 15 higher load, power enrichment, wide open throttle (EPA definition @ 100% Load)
Fuel Trim Group 5, Cells 16 - 19
• FTC 16, Automatic transmission in "Park" or "Neutral", hot idle, a/c on
• FTC 17, Automatic transmission in "Park" or "Neutral", hot idle, a/c off
• FTC 18 hot idle, a/c on (Manual or Automatic transmission in "Drive")
• FTC 19 hot idle, a/c off (Manual or Automatic transmission in "Drive")
Fuel Trim Group 6, Cells 20 - 22
• FTC 20 cold idle, a/c on or off
• FTC 21 moderate deceleration / no load
• FTC 22 higher load, power enrichment
Fuel Trim Group 1, Cells 0 - 3
• FTC 0 - 2 slight deceleration, little to no load
• FTC 3 low load, power enrichment
Fuel Trim Group 2, Cells 4 - 7
• FTC 4 low load, part throttle
• FTC 5 low load, part throttle
• FTC 6 moderate load, part throttle
• FTC 7 moderate load, part throttle, power enrichment
Fuel Trim Group 3, Cells 8 - 11
• FTC 8 - 10 moderate load, part throttle
• FTC 11 moderate load, part throttle, power enrichment
Fuel Trim Group 4, Cells 12 - 15
• FTC 12 - 14 higher load, power enrichment
• FTC 15 higher load, power enrichment, wide open throttle (EPA definition @ 100% Load)
Fuel Trim Group 5, Cells 16 - 19
• FTC 16, Automatic transmission in "Park" or "Neutral", hot idle, a/c on
• FTC 17, Automatic transmission in "Park" or "Neutral", hot idle, a/c off
• FTC 18 hot idle, a/c on (Manual or Automatic transmission in "Drive")
• FTC 19 hot idle, a/c off (Manual or Automatic transmission in "Drive")
Fuel Trim Group 6, Cells 20 - 22
• FTC 20 cold idle, a/c on or off
• FTC 21 moderate deceleration / no load
• FTC 22 higher load, power enrichment
From what I can tell, the fuel trims are carrying over from your last driving session whether you like it or not, regardless of whether it is in open or closed loop. You would technically have to reset the fuel trims every time you start the car to make sure they are all zeroed out every time. I noticed this when tuning in open loop...even though I reflashed the PCM, the trims were still there until I reset them with the HPT scanning tools. Then they stayed at zero (when tuning in open loop, of course )
Again, from what I've seen, fuel trims get remembered no matter what you are doing, as long as you are in closed loop. They then seem to apply to open loop the next time you are in them. I guess to put it another way, they learn only in closed loop, but the car uses this information later in other circumstances. Again, this is just my observation...I haven't paid all that close of attention to it.