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Please be patient with this Newguy, hes still learning.
from the suggested reading list (bar the vp v8 delco bible) i think ive worked out how blm mode works.please correct me if I'm wrong,as i understand blm is a 16 segment list with values preprogramed in from the factory to represent stoich for the engine its installed with at 200rpm increments.I'm guessing this must use the o2 sensor data and load to derive a figure.




Would it be possible to have to blm lists side by side, one for stoich one for say 22:1 and on low load cruise conditions have the ecm program switch to the leanburn list.of course most of these early leanburn systems used some device or the other to increase spark energy and induce swirl in the intake charge(increases combustion efficiency), which for myself are easily taken care of.

lean cruise is in ose 12P and vr onwards cals factory

yep, suggest running 12p and its there.

BLMs are stored in RAM, and are also known as LTFT (long term fuel trim). The ecm updates them when certain conditions are met, to keep the fueling close as physical hardware ages and performs less accurately. Its such low resolution because of the ram limitations in the '808.

so is a later ecm like vt or vx have a greater blm resolution?. also did holden ever switch to linear o2 sensors?
also i went to my nearest library and got some pc of the vp delco bible. would this community like some scans ?

VR, VS, VT, VX all had lean burn as part of their factory tune
VY, VZ (V8s at least) had the lean burn code in place but it was banned because FORD complained.
Everything was there but the enable speed was set to 412 kph and the AFR and spark advance tables
needed to be populated with a tool like EFILIVE.
Strangely after 2 years of playing I found the best economy at an AFR of 15.4, not much leaner than 14.68 as STD.
The difference in fuel economy despite the small change in mixture was huge (relatively).
Highway economy went from around 750km to 1000km per 75l tank. This was driving at the speed limit, seriously.
Cheers: Steve

VECalais-V wrote:VR, VS, VT, VX all had lean burn as part of their factory tune
VY, VZ (V8s at least) had the lean burn code in place but it was banned because FORD complained.
Everything was there but the enable speed was set to 412 kph and the AFR and spark advance tables
needed to be populated with a tool like EFILIVE.
Strangely after 2 years of playing I found the best economy at an AFR of 15.4, not much leaner than 14.68 as STD.
The difference in fuel economy despite the small change in mixture was huge (relatively).
Highway economy went from around 750km to 1000km per 75l tank. This was driving at the speed limit, seriously.
Cheers: Steve

What I wanted to experiment is if the economy can be improved further at 16-17 afr in conjunction of more timing. not sure if there is a way in 12P to have additional timing be added when lean cruise is active.

on a factory code for my VP, I found greenfoam had set the cruise areas in the AFR tables as always to be 16:1 and corresponding areas in the spare table ran around high 40s to mid 50s of timing.

I used to get stupid economy out of that car. Best effort was getting high 800s of Ks out of a tank.


A question, what the hell had ford had against Holden using lean cruise? just because they run pig rich from factory.

Banned by who? because Ford complained to who?. I don't think that's the case. My guess is it didn't work so they turned it off.

last I heard it was because burning lean increased NOX emissions, and so they had to disable it to pass the emission laws at the time?

I too thought it was emissions related.

Fairly sure as well that the later model tunes have a table to add extra timing when in lean cruise. I know my VX L67 has.

Jayme wrote:last I heard it was because burning lean increased NOX emissions, and so they had to disable it to pass the emission laws at the time?

yeah I heard something similar.