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Thread: Highway Cruise - How to raise ATF Ratio?

  1. #1
    Advanced Tuner BigDaddyCool's Avatar
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    Highway Cruise - How to raise ATF Ratio?

    I'm working toward improving economy.....

    I've adjusted many things from the forums.... Anyway I have v4 mode light throttle for around town and want to lean out the highway in v8 mode....

    I've looked around the forums and tried some stuff with no success. I'm looking at 'Spark Correction AFR Correction' and the corresponding 'Multi vs Map'.

    I've added half a degree in there, tried changing the multiplier vs manifold presssure no go.

    I've also went and adjusted the O2 Sensor Rich/Lean vs Airflow but the car seems to be overriding my settings and adjusting itself back to Stoich?

    It's getting annoying, anyone got idea's?

  2. #2
    Since the Gen 4s dont have lean cruise as long as the engine is in closed loop you cant command anything other than stoich, the only way I can think of that you could keep the car in closed loop and get lean cruise would be....
    If you turn off your LTFTs and then set you tune up so that it is deliberately lean in the RPM/load areas of the VE and area of the MAF where the engine runs at cruise to the point the STFTs cant bring it back to stoich you would be able to get your desired lean cruise however this could be very dangerous for your engine if you dont have your tune spot on. This would probably be a bit unpredictable using a MAF/VE blend or MAF only tune as the same air flow can occur at different load/speed combinations so increasing reported MAF air flow in a range to force a lean condition would happen at several different points but with a VE only tune you could accuratly add air in the exact speed/load areas you want lean crusie and leave the rest of the map as normal. However this may also create a condition where the engine goes very lean before the STFT cut into the the desired point.
    I haven't tired this and I dont even know if it would work, its just an idea I had but I thought I'd put it out there.
    2010 GXP Maloo ute, LS3, 6L80E.
    MM heads, 240/252@50 solid cam, 12.75:1 compression, 4500 Dominator converter, 3.46 rears.
    Shooting for 10s eventually.

  3. #3
    Advanced Tuner BigDaddyCool's Avatar
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    Cheers for the response explains a bit .... cause I noticed I could get it lean via the o2 voltage area...... but it'd go straight back to stoich.... thats obviously why.

    I haven't a clue yet as to doing VE tuning on the Gen4's.... just stuck with the normal maf, torque dfco and v4 mode etc.... along with gearbox tuning.

    but yeh.... thinking the only real way to save fuel is to run purely VE so yeh then I can lean out the highway area a touch....