Ross
Goblin Guru
I am near the end of may MAF (Mass Air Flow) tuning, and took the time to compare the stock 2006 Cobalt SS Supercharged MAF tune to the Goblin MAF tune.
The only difference is the shorter DF Goblin intake, with the DF supplied Edelbrock air filter, and the shorter 2.5" DF exhaust with the catalytic converter deleted.
But boy, do those changes make a difference! Or is the difference related to something else? Maybe a 13 year old MAF sensor? Do they wear?
The chart shows "MAF Frequency" in bold along the top. (spreadsheet line 3) The MAF freq. basically follows the engine RPM, with higher freq. at higher revs.
Then for yesterdays tune, the pounds per hour of measured airflow for a given MAF Freq. (line 5)
Then for the stock tune, the pounds per hour of measured airflow for a given MAF Freq. (line 8)
The stock tune is 22% lean at idle... then gets pretty close in the mid RPM range, then gets real lean again when the supercharger is screaming.
Now a stock engine will learn the LTFT (Long Term Fuel Trims) up to 20% richer, as needed... but the first while when I started driving my goblin, I was running lean.
And even after the LTFT table get filled out, the engine will still be lean in places, until the STFT (Short Term Fuel Trims) adjust... which is forgotten every time you start your car.
After I finish the MAF tuning, I am moving on to the VE (Volumetric Efficiency) tuning.
I'm really hoping this makes the throttle easier to drive a supercharged goblin.
The only difference is the shorter DF Goblin intake, with the DF supplied Edelbrock air filter, and the shorter 2.5" DF exhaust with the catalytic converter deleted.
But boy, do those changes make a difference! Or is the difference related to something else? Maybe a 13 year old MAF sensor? Do they wear?
The chart shows "MAF Frequency" in bold along the top. (spreadsheet line 3) The MAF freq. basically follows the engine RPM, with higher freq. at higher revs.
Then for yesterdays tune, the pounds per hour of measured airflow for a given MAF Freq. (line 5)
Then for the stock tune, the pounds per hour of measured airflow for a given MAF Freq. (line 8)
The stock tune is 22% lean at idle... then gets pretty close in the mid RPM range, then gets real lean again when the supercharger is screaming.
Now a stock engine will learn the LTFT (Long Term Fuel Trims) up to 20% richer, as needed... but the first while when I started driving my goblin, I was running lean.
And even after the LTFT table get filled out, the engine will still be lean in places, until the STFT (Short Term Fuel Trims) adjust... which is forgotten every time you start your car.
After I finish the MAF tuning, I am moving on to the VE (Volumetric Efficiency) tuning.
I'm really hoping this makes the throttle easier to drive a supercharged goblin.
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