Tuning with the EBL
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Re: Tuning with the EBL
I've noticed a discrepancy on some descriptions for AE Filters within the EBL documentation vs what I have found in this thread.
In documentation it says " A table of TPS filter coefficients based on coolant temperature. Used to lag the TPS value used to create the delta MAP term for AE PW. A smaller value will be a greater lag. Used to determine the duration of the TPS based AE. Also affects the magnitude of the TPS based AE." Within this thread I see it mentioned several times that the filter would be lowered to make AE come in sooner. So opposite of what the documentation says.
I want to make sure I have it correct as I am actively making changes to my AE and also want my modified XDF to be correct as well with the descriptions I added for each parameter. Can anyone verify which is correct? Intuitively a higher number is more filtering with greater lag...
In documentation it says " A table of TPS filter coefficients based on coolant temperature. Used to lag the TPS value used to create the delta MAP term for AE PW. A smaller value will be a greater lag. Used to determine the duration of the TPS based AE. Also affects the magnitude of the TPS based AE." Within this thread I see it mentioned several times that the filter would be lowered to make AE come in sooner. So opposite of what the documentation says.
I want to make sure I have it correct as I am actively making changes to my AE and also want my modified XDF to be correct as well with the descriptions I added for each parameter. Can anyone verify which is correct? Intuitively a higher number is more filtering with greater lag...
Curious what part of the EBL documentation you are referring to, so that it can be corrected in the future. Anyway, I did a deep dive on what you posted and this is what came up, which makes sense and appears the forum is correct. Have a look.The key technical explanation was captured in the search snippet. Here's a clear breakdown of what's actually correct:
The Documentation is Wrong (or at best, misleading) — The Forum Consensus is Right
Your intuition is correct, and so is the forum thread. Here's the precise technical explanation:How the Lag Filter Actually Works
The ECM reads the TPS sensor and lag-filters it every 12.5 milliseconds (80 times per second). The filter coefficient controls how quickly the filtered output chases the raw input. Third Generation F-Body Message BoardsThe math that matters: Delta TPS = Current TPS − Lagged (filtered) TPS
This delta value is what drives AE. So:
- Smaller coefficient → slower filter → output lags further behind input → LARGER delta → more AE, sooner and longer
- Larger coefficient → faster filter → output catches up quickly → SMALLER delta → less AE
So What's Wrong With the Documentation?
The documentation statement — "A smaller value will be a greater lag" — is technically correct on its own. A smaller coefficient does produce greater lag. The problem is the phrasing implies this is a bad thing or means AE comes in slower, when in fact greater lag = larger delta TPS = AE kicks in harder and faster from the tune's perspective.The forum saying "lower the value to make AE come in sooner" is correct in practice — lowering the coefficient increases the lag between raw and filtered TPS, which inflates the delta, which triggers a stronger AE response.
For Your XDF Description
Here's how I'd word it accurately:AE TPS Filter Coefficient (vs. Coolant Temp): Controls the lag rate of the TPS filter used to calculate delta TPS for AE. A smaller value = more lag = larger delta TPS = stronger and longer AE. A larger value = less lag = smaller delta = weaker, shorter AE. Affects both the magnitude and duration of TPS-based AE.
Smaller filter values result in larger delta TPS values, impacting the AE threshold, volume, and duration. Scribd
Your intuition that "higher number = more filtering with greater lag" is actually backwards — it's a counterintuitive parameter. Higher number = faster response (less lag), lower number = slower filter (more lag = more AE). The forum thread has it right
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Re: Tuning with the EBL
Originally Posted by dabomb6608
I want to make sure I have it correct as I am actively making changes to my AE and also want my modified XDF to be correct as well with the descriptions I added for each parameter. Can anyone verify which is correct? Intuitively a higher number is more filtering with greater lag...
- Rob
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Joined: Mar 2006
Posts: 309
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From: Arizona
Car: 82 Corvette - CFI
Engine: 383 - Renegade, AFR 195, Bullet cam
Transmission: 700R4 - 3,200 Yank TC
Axle/Gears: 3.31
Re: Tuning with the EBL
Thanks Rob for chiming in on this. You know this probably better than anybody on here. You always give great advice.
Also, can you contact me when you get the time? Thanks.
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