I don't know if there is any interest in some information I discovered releative to air fuel ratios, timing, and other changes in the E38 ECM for the LS9, but if so, I would be happy to share some calibrations I found. Some are pretty amazing. For instance:
The target air fuel ratio for Open Loop in now 39% added fuel to the stoichiometric value in Closed Loop. That means that at full tilt, the ZR1 has an air fuel ratio of 10.56:1 compared with the Z06 ratio of 11.25:1. Stoichiometric for E10 fuel is 14:1. That means that every drop of fuel enrichment below that ratio goes out the tailpipes. That is just the beginning of GMs fuel parameters. The IVT Gain is over 50%!!.
What do you think your throttle position is to enter Open Loop?
As much as 64% more fuel to cool the Intake Valve Temp.
The ZR1 goes into Open Loop at 19% throttle position. This means that if you drive with your foot just north of 20% throttle position, you are always running 10.5:1 air fuel ratios.
E85 fuel has a stoichiometric value of 9.8:1, and the ECM is set up to run E85 by the looks of it. 105 native octane could mean some big numbers on this fuel with the right timing. E85 has its own Open Loop table, with is much less aggressive than the E0 tables.
I do not recommend trying E85, but my E85 Escalade has the same computer and tables as the LS9.
Tommorow, I will post the airflow tables, which are now wideband. The MAF tables are good to 1897 Gm/sec now, in case you get the desire to put a thimble in place of the pulley from the factory. Stock Z06 goes to 512 Gm/Sec and does not use that much until you poke a Katech cam into it.
I will compare the airflow tables with the LS3 airflow tables which should be interesting since both motors come from the 6.2 L platform.
You will see the difference just the blower makes.
I don't know if there is any interest in some information I discovered releative to air fuel ratios, timing, and other changes in the E38 ECM for the LS9, but if so, I would be happy to share some calibrations I found. Some are pretty amazing. For instance:
The target air fuel ratio for Open Loop in now 39% added fuel to the stoichiometric value in Closed Loop. That means that at full tilt, the ZR1 has an air fuel ratio of 10.56:1 compared with the Z06 ratio of 11.25:1. Stoichiometric for E10 fuel is 14:1. That means that every drop of fuel enrichment below that ratio goes out the tailpipes. That is just the beginning of GMs fuel parameters. The IVT Gain is over 50%!!.
What do you think your throttle position is to enter Open Loop?
I thought the LS9 used the E67 ECM for use with a 2-Bar Map Sensor?
so what are the cliffs notes for those of us not up on the terminology?
Rich = conservative, safe
Lean = risky, potential damage
Perfect Stoichiometric balance means that it is neither too rich or too lean. You will see that there are different values for each fuel type.
The air fuel ratio is set up very conservatively meaning there may be more power to be had with tuning. The computer in the car monitors the air fuel ratio and makes adjustments to achieve the proper mixture as defined in the set of perimeters within the computer this is referred to as the table, like a spread sheet. When the car is in open loop the fuel level is fixed without monitoring the air fuel ratio. When the car is in closed loop the car monitors the feed back from several sensors including the O2 sensor and makes on the fly adjustments. It's not unlike the climate control system in your car. You set a temp and the cars climate control system measures the temp inside the car and adjusts the output to match the set point. If you set the car to MAX AC then the system just cranks out 100% of it's capacity all the time.
As you go from rich towards lean the power level generally increases. If you get too lean the fuel in the cylinder will auto ignite before the cylinder reaches top dead center. This is called a ping or a knock and it can just make a bad sound, burn a hole in the piston or the forces may cause a component to fracture under the stress. Auto manufactures attempt top avoid this condition by tuning on the conservative side especially with forced induction motors. Tuners attempt to take advantage of the generally conservative tune and adjust parameters in the table to move the air fuel ratio closer to the perfect stoichiometric balance there by increasing power.
Corvette Store
Inside the ZR1 ECM
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rather than put down someone helping out with some interesting info.
Stock Z06 goes to 512 Gm/Sec and does not use that much until you poke a Katech cam into it.
