Anyone have info on this subject pertaining to lt1's? Is this possible without running in open loop all the time? This really is pertaining to closed loop a/f tables and info on changing the o2 switch points to acheive ~16.5 CLOSED loop. Is a mail-order tuner capable of doing this?

 

They do not use it but remor has it something is burried in the programming. Has to be open loop though since narrowband O2s are very strictly only accurate at 14.7afr.

 

The Holden LS1's have it programmed from the factory and I believe they use standard 02 sensors. Not sure if the lean cruise puts it in open loop on the holden's?

I know some LS1 owner's change the o2 switch points to get better mileage in closed loop but I don't know of anyone who has tried this on LT1's or if it is possible. I would have thought someone would have tried it.

 

any tuners care to comment??

 

Its not possible for LT1s or LS1s except for LS1s overseas. The reason is because of emissions.. the lean cruise while gets better mileage, creates more pollutants.

 

Lean cruise works fine with narrow band o2's.

The ECM knows what correction gets 14.7 to 1 air fuel by watching crossover points. It then caculates a leaner ratio and runs that. On the TPI systems and on my 90 cavalier, the ecm will come out of lean cruise every 60 seconds to check where it 's at.

Any time manifold vacuum goes above 50kpa it comes out of lean cruise as well.

It also has minimum speed for lean cruise. It has nothing to do with changing the o2 crossover points.

 

I think you are confusing lean cruise for closed loop. changing the crossover points for the o2 sensors will cause the computer to only correct the mixture if it is really off. In effect it dumbs down the sensor. LS1 guys do this a lot so it does work. No one here seems to know anything about it though.