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v3mafadjcombft [2009/06/11 14:16]
twdorris
v3mafadjcombft [2024/03/15 11:16] (current)
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 A good understanding of [[v3combinedft|CombinedFT]] and [[fueltrimupdatepoints|fuel trim in general]] will help a lot with your understanding of this function. A good understanding of [[v3combinedft|CombinedFT]] and [[fueltrimupdatepoints|fuel trim in general]] will help a lot with your understanding of this function.
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 ====== STEP 3: Data Capture ====== ====== STEP 3: Data Capture ======
 Add the following log items to your captured values (F10): CombinedFT, MAFRaw and ClosedLoop Add the following log items to your captured values (F10): CombinedFT, MAFRaw and ClosedLoop
  
-Make sure the engine is at full operating ​temperatures.  You don't want to mess with coolant based variations at this point. ​ You want to stabilize everything you can first and then adjust based on the one variable left (presumably airflow variation).+Make sure the engine is at full operating ​temperature.  You don't want to mess with coolant based variations at this point. ​ You want to stabilize everything you can first and then adjust based on the one variable left (presumably airflow variation).
  
 Once you're satisfied that the requirements above have been met, you're ready to grab a datalog. ​ Let the car idle for about a minute. ​ Then go drive. ​ Try to keep the car in closed loop mode as much as possible (more on that in the advanced section). Once you're satisfied that the requirements above have been met, you're ready to grab a datalog. ​ Let the car idle for about a minute. ​ Then go drive. ​ Try to keep the car in closed loop mode as much as possible (more on that in the advanced section).
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 The image below shows a fairly typical setup for the various open loop threshold tables you can use to extend closed loop mode for this test.  Keep in mind what you're doing here, though. ​ You're basically telling the ECU to maintain stoich air fuel ratios under more load (LoadFactor) and with more throttle. ​ This could very well produce a hotter mixture than you'd like to maintain for any lengthy period of time.  So monitor EGTs if possible or if not, just try not to stay under high load/closed loop mode for very long. The image below shows a fairly typical setup for the various open loop threshold tables you can use to extend closed loop mode for this test.  Keep in mind what you're doing here, though. ​ You're basically telling the ECU to maintain stoich air fuel ratios under more load (LoadFactor) and with more throttle. ​ This could very well produce a hotter mixture than you'd like to maintain for any lengthy period of time.  So monitor EGTs if possible or if not, just try not to stay under high load/closed loop mode for very long.
  
-{{ http://​www.ecmtuning.com/​images/​forums/​mafadjcombft/​olthresholds.png }}+{{ https://​www.ecmtuning.com/​images/​forums/​mafadjcombft/​olthresholds.png }}
  
 With that table in place, you can grab a datalog with a bit more load variation. ​ Personally, I like to find a nice hilly area and apply light throttle to vary LoadFactor between 0.9 to 1.3 while maintaining closed loop operation. ​ This driving combined with the typical flat road driving (with LoadFactors around 0.6-0.9), combined with typical idle and free rev (LoadFactors around 0.3-0.4) really produces a good set of data for this function. With that table in place, you can grab a datalog with a bit more load variation. ​ Personally, I like to find a nice hilly area and apply light throttle to vary LoadFactor between 0.9 to 1.3 while maintaining closed loop operation. ​ This driving combined with the typical flat road driving (with LoadFactors around 0.6-0.9), combined with typical idle and free rev (LoadFactors around 0.3-0.4) really produces a good set of data for this function.
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 I'll walk through a sample calibration of my own car below. ​ This is a 1995 AWD Talon with 850 injectors running E85 and a GM 3" MAF connected to the ECU.  The MAF is installed just before the throttle body using upper IC piping that has flared 3" ends as shown below. I'll walk through a sample calibration of my own car below. ​ This is a 1995 AWD Talon with 850 injectors running E85 and a GM 3" MAF connected to the ECU.  The MAF is installed just before the throttle body using upper IC piping that has flared 3" ends as shown below.
  
-{{ http://​www.ecmtuning.com/​images/​forums/​gmmafinstall.jpg }}+{{ https://​www.ecmtuning.com/​images/​forums/​gmmafinstall.jpg }}
  
 Download the datalog below to review the initial drive cycle (20 minutes or so) and setup. ​ The things to note include the global fuel setting and the MAF compensation. Download the datalog below to review the initial drive cycle (20 minutes or so) and setup. ​ The things to note include the global fuel setting and the MAF compensation.
  
-[[http://​www.ecmtuning.com/​images/​forums/​mafadjcombft/​talon2ggm30-mafadj.2008.12.26-01.elg|Initial drive cycle and setup log]]+[[https://​www.ecmtuning.com/​images/​forums/​mafadjcombft/​talon2ggm30-mafadj.2008.12.26-01.elg|Initial drive cycle and setup log]]
  
 Global fuel is set appropriately for 850s on stock base pressure running E85 using the following formula: Global fuel is set appropriately for 850s on stock base pressure running E85 using the following formula:
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 Once that drive was done, I did the "MAF Adj: CombinedFT"​ function and got the following results. ​ The white dots below are the "​suggested template"​ values produced by this function.  ​ Once that drive was done, I did the "MAF Adj: CombinedFT"​ function and got the following results. ​ The white dots below are the "​suggested template"​ values produced by this function.  ​
  
-{{ http://​www.ecmtuning.com/​images/​forums/​mafadjcombft/​initialresults.png }}+{{ https://​www.ecmtuning.com/​images/​forums/​mafadjcombft/​initialresults.png }}
  
 I have selected (highlighted) the data points for which the function provided some adjustments for clarity. ​ Looking at these points, I'm pretty happy with the values. ​ Nothing is maxed out and there aren't huge variations from point to point. ​ So I'm just going to click "Use template"​. I have selected (highlighted) the data points for which the function provided some adjustments for clarity. ​ Looking at these points, I'm pretty happy with the values. ​ Nothing is maxed out and there aren't huge variations from point to point. ​ So I'm just going to click "Use template"​.
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 Looking at the 1700 and 1800hz points, I feel a need to tweak them a bit.  They'​re just flat where as the points before and after are not.  So I'm going to slightly adjust those two points so that they make a more natural transition between the 1600 and 1900 points. ​ After doing that, you can see the new results below. Looking at the 1700 and 1800hz points, I feel a need to tweak them a bit.  They'​re just flat where as the points before and after are not.  So I'm going to slightly adjust those two points so that they make a more natural transition between the 1600 and 1900 points. ​ After doing that, you can see the new results below.
  
-{{ http://​www.ecmtuning.com/​images/​forums/​mafadjcombft/​resultsmod1.png }}+{{ https://​www.ecmtuning.com/​images/​forums/​mafadjcombft/​resultsmod1.png }}
  
 So what about the points above the 1900hz? ​ Well, that will involve some sort of wide open throttle tuning and will need to be covered in more detail in a different article using a different approach. ​ For now, what I did was to make one quick pull in that datalog above. ​ You can find it around 1194 seconds into the file. So what about the points above the 1900hz? ​ Well, that will involve some sort of wide open throttle tuning and will need to be covered in more detail in a different article using a different approach. ​ For now, what I did was to make one quick pull in that datalog above. ​ You can find it around 1194 seconds into the file.
  
-{{ http://​www.ecmtuning.com/​images/​forums/​mafadjcombft/​resultslog.png }}+{{ https://​www.ecmtuning.com/​images/​forums/​mafadjcombft/​resultslog.png }}
  
 What you see in that log section is BoostEst lined up with measured boost (GM3Bar). ​ Notice how the two slowly separate for a short period of time and then the difference between them stabilizes around 4700 RPM (2481 hz).  I'm going to pick that stabilizing point as my next adjustment index. What you see in that log section is BoostEst lined up with measured boost (GM3Bar). ​ Notice how the two slowly separate for a short period of time and then the difference between them stabilizes around 4700 RPM (2481 hz).  I'm going to pick that stabilizing point as my next adjustment index.
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 So I'm going to move the 2500hz adjustment point (and all the others above that) down to around -9.1%. ​ Then I just need to interpolate a smooth line between the 1900hz point where we had some data before and the 2500hz point where we have new data now.  The final results are shown below. So I'm going to move the 2500hz adjustment point (and all the others above that) down to around -9.1%. ​ Then I just need to interpolate a smooth line between the 1900hz point where we had some data before and the 2500hz point where we have new data now.  The final results are shown below.
  
-{{ http://​www.ecmtuning.com/​images/​forums/​mafadjcombft/​resultsfinal.png }}+{{ https://​www.ecmtuning.com/​images/​forums/​mafadjcombft/​resultsfinal.png }}
  
 This is my new, final configuration. ​ To get that centered nicely, I'll click the "​Change..."​ button next to "​Global scalar"​ field and then click "Auto Adj" on the dialog that pops up.  The application will center the current set of adjustments for me and produce an appropriate global scalar value. ​ I'll then do an "​ECU->​Reset fuel trims" and go drive. ​ Everything should line up much better now. This is my new, final configuration. ​ To get that centered nicely, I'll click the "​Change..."​ button next to "​Global scalar"​ field and then click "Auto Adj" on the dialog that pops up.  The application will center the current set of adjustments for me and produce an appropriate global scalar value. ​ I'll then do an "​ECU->​Reset fuel trims" and go drive. ​ Everything should line up much better now.
v3mafadjcombft.1244744202.txt.gz ยท Last modified: 2009/06/11 14:16 by twdorris