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quickieafsetup [2008/01/23 06:42]
76.100.119.159
quickieafsetup [2024/03/15 11:16] (current)
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-====== ​Overview ​======+====== ​Quickie A/F Setup ======
 I was asked to store this post away somewhere for future reference. ​ For now, I'll just dump it in here as is and maybe come back later and edit/expand upon it.  It's really just documentation of my personal process for running through a "​quickie"​ setup with a new car using DSMLink. ​ It's intended to help the user get a handle on whether fuel delivery and airflow metering all make sense. I was asked to store this post away somewhere for future reference. ​ For now, I'll just dump it in here as is and maybe come back later and edit/expand upon it.  It's really just documentation of my personal process for running through a "​quickie"​ setup with a new car using DSMLink. ​ It's intended to help the user get a handle on whether fuel delivery and airflow metering all make sense.
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 ====== Process ====== ====== Process ======
-First, if you don't already know what fuel trims are or how they'​re used by the ECU, then I would strongly recommend you start by reading through [[FuelTrimUpdatePoints]]. ​ Knowledge of this fundamental concept is key to understanding everything else below.+===== Fuel trims ===== 
 +First, if you don't already know what fuel trims are or how they'​re used by the ECU, then I would strongly recommend you start by reading through [[FuelTrimUpdatePoints|Fuel-trims:​ What They Are and How They Work]]. 
 + 
 +Knowledge of this fundamental concept is __**key**__ to understanding everything else below
 + 
 + 
 +===== Idle ===== 
 +I generally monitor ''​CombinedFT''​ and ''​AirflowPerRev''​ at idle.  I want to see ''​CombinedFT''​ cycling around +/- 8% or so. 
 + 
 +You'd expect to see 0.24-0.28 g/rev for ''​AirflowPerRev''​ at idle ((Automatics and 2.3L engines will generally have a slightly higher AirflowPerRev value at idle.)), but I don't get too caught up on that if the fuel trim is inline and global fuel settings make sense for the injectors that are installed. 
 + 
 +If fuel trim at idle is not where I want it, I either use the lower airflow sliders (log ''​MAFRaw''​ to see where to make adjustments) or I use deadtime to tweak things. ​ If I'm running SD, I'll use the SD VE table instead of the airflow sliders. 
 + 
 +Whether I make changes to airflow or deadtime usually depends on whether ''​AirflowPerRev''​ is inline or not. If ''​AirflowPerRev''​ is off from the expected value in the opposite direction from ''​CombinedFT'',​ then I adjust the lower airflow sliders more than deadtime.
  
-I generally monitor ''​STFT''​ and ''​AirflowPerRev'' ​at idle. want to see ''​STFT''​ cycling around 0% with ''​LTFTLo''​ around +/- 5% or so. You'd expect ​to see 0.28 g/rev for ''​AirflowPerRev''​ at idle ((Automatics and 2.3L engines will generally have a slightly higher AirflowPerRev value at idle.))but I don't get too caught up on that if the fuel trims are inline with global fuel settings that make sense for my injectors.+If ''​AirflowPerRev'' ​is around what I'd expect, I might focus on deadtime instead ​for idle fuel trim adjustmentsJust keep an ear out for little misfires ​at idle that can sometimes be introduced with deadtime adjustmentsparticularly ​if the injectors ​are not well matched at low pulsewidth.
  
-If fuel trims at idle are not where want themI either use the lower airflow sliders (50 and //maybe// 150hz sliders) or I use deadtime to tweak things. Which I use usually depends on whether ​''​AirflowPerRev'' ​is inline or notIf ''​AirflowPerRev''​ is off from 0.28 g/rev in the opposite direction from ''​LTFTLo'',​ then I adjust the lower airflow ​sliders ​more than deadtimeIf ''​AirflowPerRev''​ is around 0.28 g/rev, I might focus on deadtime instead for idle fuel trim adjustments. Just keep an ear out for little misfires at idle that can sometimes be introduced with deadtime adjustments,​ particularly if the injectors are not well matched at low pulsewidth.+===== Cruise ===== 
 +Next do some cruising aroundagain watching ​''​CombinedFT'' ​to see where it likes to hang outI don't really have a good airflow ​figure to watch for at cruise because it depends much more on throttle position and road inclination ​than idle airflow doesSo it's hard to pick a value there.
  
-Next I do some cruising around, again watching ''​STFTs''​ to see where they like to hang out. I don't really have a good airflow figure to watch for at cruise because it depends much more on throttle position and road inclination than idle airflow does. So it's hard to pick a value there. ​I just watch ''​STFTs''​ and try to adjust airflow sliders or fuel settings accordingly. I would consider airflow slider adjustments if I know I have reason to suspect airflow to be off a bit (maybe I'm dialing in a hacked MAF or something). I would focus on fuel settings more if ''​LTFT''​ were off for both idle and cruise.+I just watch ''​CombinedFT''​ and try to adjust airflow sliders or fuel settings ​(primarily deadtime and/or global fuel sliders) ​accordingly. I would consider airflow slider adjustments if I know I have reason to suspect airflow to be off a bit (maybe I'm dialing in a hacked MAF or something). I would focus on fuel settings more if ''​LTFT''​ were off for both idle and cruise.
  
-Then I do few pulls and look at ''​BoostEst''​ around 5500-6000 RPM to make sure it matches with what the gauge was readingSome deviation is expectedespecially as revs increase. But more than a psi or two and I feel like I want to tweak the airflow sliders some more.+===== Automated adjustments ===== 
 +**NOTE:** With the release of V3, we've added more "​automated"​ method of doing the above idle/cruise dialing. ​ Be sure to read about it on our [[v3mafadjcombft|MAF Adjust page]] Orif you're running SD, read the [[sdveadjcomft|SD Adjust page]] ​or the [[sdveadjsdratio|SDRatio Adjust page]].
  
-At that point, I'm usually pretty happy with the setup and can start tuning. 
  
-If you have WBO2 wired into the ECU for dataloggingthen you can do even more checks ​and verification. In that case, set the estimated A/F Ratio properties ​to match my global fuel settings ​and see where the estimated A/F Ratio differs from the measured.+===== WOT ===== 
 +Then I do few pulls and look at ''​BoostEst''​ around 5500-6000 RPM to make sure it matches with what the gauge was reading. Some deviation is expectedespecially as revs increase. But more than a psi or two and I feel like I want to tweak the airflow sliders some more.  You can calculate the amount ​to move the sliders if you understand absolute pressure ​and how to calculate scale factors. ​ Otherwise, just lower the MAFComp sliders if BoostEst is above measured boost or raise MAFComp is BoostEst is lower than measured ​boost.
  
-In all cases, I constantly do cross checks. For example, if ''​LTFTLo''​ at idle is positive by a good bit (more than 5%) yet ''​AirflowPerRev''​ is also higher than 0.28 and my deadtime has already been increased a good bit from where I'd expect itthen have to question what's going on because ​the numbers don't add up. Maybe fuel pressure at idle is higher than what I assumed it was, for example.+Once that's done, I'm usually pretty happy with the setup and can start tuning.
  
 +===== Other checks =====
 +If you have a WBO2 wired into the ECU for datalogging,​ then you can do even more checks and verification. In that case, I set the estimated A/F Ratio properties to match my global fuel settings and see where the [[AFRatioItem|estimated A/F Ratio]] differs from the measured.
  
 +In all cases, I constantly do cross checks. For example, if ''​CombinedFT''​ at idle is positive by a good bit (significantly more than 5%) yet ''​AirflowPerRev''​ is also higher than expected (0.24-0.26) and my deadtime has already been increased a good bit from where I'd expect it, then I have to question what's going on because the numbers don't add up. Maybe fuel pressure at idle is lower than what I assumed it was, for example.
  
quickieafsetup.1201088535.txt.gz · Last modified: 2008/01/23 06:42 by 76.100.119.159