Lean Cruise Settings

[L67PSI]

Hi all,

Just wondering what the table "Lean Cruise Spark Advance Trim" actually does??
I see it has figures like 1.76. Is this timing that is added or removed.

Also what does "Lean Cruise AFR Correction Vs mg/cyl Vs RPM" do? Is it say 14.7 commanded afr, then +2.4 to make new afr of 17.1:1?? or is it a percentage??

If anyone can explain that would be great.

With a 82c thermostat, is enabling lean cruise at 74/75c ok?

Thanks

[The1]

yep, spark trim is just that, so it trims the amount off the spark, so if it's 3 degrees then it will remove 3 degrees. The AFR table is an adder ontop of 14.7, so 1.0 will make 15.7 as the target, you will see the result in the datalogs by checking the AFR target item. That coolant is fine, i would even make it 70c as the coolant temp will drop below that in winter even while highway driving.

[Dylan]

Is it best to remove spark over adding spark at a leaner AFR?

[The1]

use the Knock Active Loops and Knock Retard to gauge that, like any normal tuning. The best torque point would then save throttle causing more fuel.

[immortality]

Doesn't it add timing? Doesn't a lean mixture takes longer to burn so you would want to ignite it sooner to get peak pressure at the right time.

[Holden202T]

are those AFR offsets stock holden ? 14.7 + 3.45 = 18.15 .... that's pretty lean!

[immortality]

are those AFR offsets stock holden ? 14.7 + 3.45 = 18.15 .... that's pretty lean!

Yep

[L67PSI]

are those AFR offsets stock holden ? 14.7 + 3.45 = 18.15 .... that's pretty lean!

Yes I believe its standard. I'm using The1 enhanced bin, VT L67 bin file.

[L67PSI]

If I was to add timing could I for example use Table (Lean Cruise Spark Advance Trim) -1.76 or -2.76??? Would that work?

[VL400]

That spark table will already be adding spark, negative numbers are to reduce advance. You can log this though, will see it enter lean cruise and modifiy timing and target AFR.

Its worth changing the AFR offset to something a little less though. An offset of 1 AFR or less tends to be better. Wont really gain economy above mid 15 AFRs as you start losing torque and run the risk of a lean misfire.