JDM MAP sensor vs real load value
Nov 6, 2006, 11:10 AM
#1
Evolved Member
Thread Starter
JDM MAP sensor vs real load value
As per attached. This is a run through third gear - I went WOT just before 3000 RPM. Forgive the underdamped boost response with the depression at 4500 RPM. However, this post is not to show off my poor boost control 
I changed request ID 0 and 1 to output the two bytes of load by changing the MUT table that Bez Bashni found in his Evo VII. You can see the divergence at high RPM as the VE falls as we've previously discussed.
Although there is a risk of errors on wraparound as the high byte increments or decrements during a read, for simple datalogging these easily stand out, and this true load value is easy enough to implement and useful to me. It also retains compatibility with factory scan tools and normal datalogging as the baud rate and replies are standard.
I changed request ID 0 and 1 to output the two bytes of load by changing the MUT table that Bez Bashni found in his Evo VII. You can see the divergence at high RPM as the VE falls as we've previously discussed.
Although there is a risk of errors on wraparound as the high byte increments or decrements during a read, for simple datalogging these easily stand out, and this true load value is easy enough to implement and useful to me. It also retains compatibility with factory scan tools and normal datalogging as the baud rate and replies are standard.
Nov 20, 2007, 05:25 AM
#3
Evolving Member
MPA vs Load
My MAP(kpa) vs 2 byte load seems to have wider gap - 20-30.
As you see in attached MAP, then lower Load calculated and the 2byte load. I do not know why the gap between load calc and 2byte load is so huge.
As you see in attached MAP, then lower Load calculated and the 2byte load. I do not know why the gap between load calc and 2byte load is so huge.
Nov 20, 2007, 09:00 AM
#6
Evolved Member
Thread Starter
If your induction system is non standard that can typically lower the airflow readings, which gives lower load values for a given boost level. Sometimes the error is more than 10%.
Nov 20, 2007, 09:15 AM
#7
Evolving Member
Oh well I see now. I have only changed the standard air filter unit for a conic filter. Comparing airflow before and after - I observed a slight increase in airflow readings (cca 120Hz).
One thing that I am unclear is that I am not hitting the 1603Hz peak (when it was like 25 degrees outside - I hit it at 6200RPM) - in the 16degC - it was approximatelly 100Hz lower). Of courser my Evo8 with conic filter and 3"TBE and a mild tune cannot be compared to evo IX where I have seen 1603Hz in their logs far sooner - but anyway I think I am flowing not enough air
One thing that I am unclear is that I am not hitting the 1603Hz peak (when it was like 25 degrees outside - I hit it at 6200RPM) - in the 16degC - it was approximatelly 100Hz lower). Of courser my Evo8 with conic filter and 3"TBE and a mild tune cannot be compared to evo IX where I have seen 1603Hz in their logs far sooner - but anyway I think I am flowing not enough air
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