Spark MAP, SD Tuning Question
Thread Starter
TECH Resident
Joined: Aug 2003
Posts: 970
Likes: 4
From: England UK
Spark MAP, SD Tuning Question The spark table workes from RPM and g/cyl (calculated from MAF I guess)
If you remove the MAF then the Spark table would have no depth, you would expect it to run from one line as there is no g/cyl input. When logging you can see the spark advance changing depending on throttle position, therefore it must be using something to substiture the g/cyl, but what is it? is it using MAP?
If you remove the MAF then the Spark table would have no depth, you would expect it to run from one line as there is no g/cyl input. When logging you can see the spark advance changing depending on throttle position, therefore it must be using something to substiture the g/cyl, but what is it? is it using MAP?
TECH Addict
Joined: Mar 2004
Posts: 2,336
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From: Fat Chance Hotel
Calculated airflow. The MAF submits the actual airflow ( via MAF calibration). The computer can then calcuate what the airflow should be and compare. There is a threshold rpm setting for when the MAF is in steady state for the PCM to use the MAF exclusively. If the PCM is in SD mode, it will use the calcuated airflow based on VE...and baro I think.
