lean cruise in OS3

[horsepower1]

Is it possible to enable lean cruise in OS3 - It would be nice to get a 14.7 cruise, over 65mph

[Tordne]

Lean Cruise is only available on Holden platforms. It is hard coaded in the PCM OS and will not be changed by EFILive. The best you can do is use the B3647 table to command leaner mixtures.

You will want to run leaner than 14.7:1 more then likely as well. 15.4:1 seems like a common target.

[horsepower1]

I really need a lean cruise, set by MPH. I need the richer mixture down low for low speed driving, but once over 65, the car could take a leaner mixture without bucking. Lean cruise would work perfect, as it toggles by MPH and steady state. I was hoping to use lean cruise as a kind of closed loop mechanism only on highway speeds...not really to run lean, but to run at 14.7 at highway speeds. The MAP/RPM or TP/RPM won't cut it, because the same points are used at low speeds, but the difference is the bucking at low speeds. The low-speed driveability is more important than saving some fuel at cruise. Any suggestions?

[Tordne]

Were you going to try the TPS VE in OS5?

[horsepower1]

Were you going to try the TPS VE in OS5?

I originally planned to, but my MAP is surprisingly steady enough that I don't think the TPS VE is necessary/advantageous for this cam/car. I'm running OS3 and it works beautiful - AFR is right on, idle is smooth, transcient is smooth, minimal cam-buck. Only thing I'd like to do is score a slightly leaner cruise AFR - big cube engine could use the diet :)

[TAQuickness]

I've found more fuel savings in DFCO than lean cruise.

[horsepower1]

I've found more fuel savings in DFCO than lean cruise.


Thanks - yes, that looks like it might be the only option -
how has the transition in/out been? I'll have to play with it -

[TAQuickness]

I have mine set pretty agressive. You can definately feel the transition.

[minytrker]

I leaned my h/c z06 out to about 15.1-15.5 and my milage went down. It could have been because of the huge cam, not forsure. I still get 31mpg with 500hp.

[TAQuickness]

I leaned my h/c z06 out to about 15.1-15.5 and my milage went down. It could have been because of the huge cam, not forsure.

I went from 15.6 at cruise to 13.8 and picked up 3 mpg.


I still get 31mpg with 500hp.

:Eyecrazy: Not bad. I was happy to get 21mpg on the hiway. I'd like to see how you did this.

[Tordne]

I went from 15.6 at cruise to 13.8 and picked up 3 mpg.

Have you revalidated this. It just seems strange to run rich and gain mpg :eek:

[TAQuickness]

Have you revalidated this. It just seems strange to run rich and gain mpg :eek:

Every day for the last month. I think it has more to do with the actual AFR in the cylinder than what the WB is reading. It takes x amount of power to hold the vehicle at a steady speed. The less work it takes to make that power, the more economy you'll realize.

[oztracktuning]

Tuning for torque seems to be the key. I got a customers car to give 43mpg over a 60mile period at about 60mph. It was a M6 3.45 VX LS1 running OS3. Desired afrs at cruise 15.6:1 , very active DFCO and a lot of timing near cruise cells maximizing just off cruise torque. The car is super smooth.

Its mods are 4 into 1s, metal cats, improved CAI, 160 thermo

[minytrker]

I went from 15.6 at cruise to 13.8 and picked up 3 mpg.



:Eyecrazy: Not bad. I was happy to get 21mpg on the hiway. I'd like to see how you did this.

Autotune and timing I think gets great results for gas mileage on the highway. Im running C.O. #3 but at cruise its still running off the o2s going for 14.7. I get on the highway with the cruise set at 70-80mph I get 28-31mpg. Now around town the way I drive it sucks down gas pretty bad. Whats funny is when the car was bone stock untuned it only got 28mpg. I have added 100hp at the wheels and get 3 more mpg now, got to love it.

[oztracktuning]

Get DFCO happening more aggressively and work on getting more timing advance at low loads particularly at low rpms.

[Extinct]

What sort of DFCO is working best ?

[horsepower1]

Autotune and timing I think gets great results for gas mileage on the highway. Im running C.O. #3 but at cruise its still running off the o2s going for 14.7. I get on the highway with the cruise set at 70-80mph I get 28-31mpg. Now around town the way I drive it sucks down gas pretty bad. Whats funny is when the car was bone stock untuned it only got 28mpg. I have added 100hp at the wheels and get 3 more mpg now, got to love it.


How do you get cruise to run off 02s -- this is exactly what I am after. Seems like lean cruise could do it perfect, if enabled.

[oztracktuning]

Lean cruise doesnt run off the 02s - it needs an accurate VE table - i think thats how it works anyway.

[horsepower1]

Lean cruise doesnt run off the 02s - it needs an accurate VE table - i think thats how it works anyway.




it must have some feedback, as it has correction parameters. To correct, it must have some feedback, I'd assume from 02s.