Running leaner than "Stoich" with MAF meter still being used?

[rel3rd]

Probably a dumb question, but is there a way to force the vehicle to cruise at a leaner than stoichemetric AFR without doing a Speed Density tune?

I guess I'm wondering if MAF can somehow be less involved in cruise AFR?

[vic_dahn]

I have the same exact question. Thank you for asking this!

[Mr.IH]

I`m no expert but how about Lean Cruise mode?

[rel3rd]

I`m no expert but how about Lean Cruise mode?

I'd always read here that "Lean Cruise Mode" wasn';t functional on US vehicles?

[vic_dahn]

I'd always read here that "Lean Cruise Mode" wasn';t functional on US vehicles?

That is what I have read also..

[rel3rd]

Probably a dumb question, but is there a way to force the vehicle to cruise at a leaner than stoichemetric AFR without doing a Speed Density tune?

I guess I'm wondering if MAF can somehow be less involved in cruise AFR?

Anyone???

[98vortecSilverado]

O2 rich/lean vs airflow. I'm not sure how far you could get it to go, and I'm sure it would take a bit of trial and error, but I believe you could lean it out some. You should figure out which airflow mode you're in when cruising and just change those cells. I'm pretty sure there's several threads about it on here if you want to try searching.

[2xLS1]

Speed density itself won't do it if still running closed loop. You would have to run open loop or enable lean cruise with other tuners. You can't enable LC with HPT. Even with LC you don't gain much MPG without other tune changes to go along with it.

[rel3rd]

O2 rich/lean vs airflow. I'm not sure how far you could get it to go, and I'm sure it would take a bit of trial and error, but I believe you could lean it out some. You should figure out which airflow mode you're in when cruising and just change those cells. I'm pretty sure there's several threads about it on here if you want to try searching.

I had tried that a few years ago, and saw no change whatsoever. I was hoping there was another way found in the time it's been. I guess not.

Speed density itself won't do it if still running closed loop. You would have to run open loop or enable lean cruise with other tuners. You can't enable LC with HPT. Even with LC you don't gain much MPG without other tune changes to go along with it.

Yeah, this is just for my truck, trying to gain a little more MPG...probably not worth the aggravation. Thanks for the replies.

[vic_dahn]

I am new so I may be talking nonsense..

Why dont we change the O2 Rich/lean vs Airflow bank 1 and bank 2 tables to a lower voltage?Capture 4.JPG I may try this but I will have a WB hooked up soon. Do you think we can tune more fuel into it with the PE table for hard acceleration?

[jimmyblue]

Changing the O2 switchpoint will pull your closed loop AFR.
I've played with this. Below about 300mV I started to see
a bit of surge in cruise control. I did not play with timing.

PE mode is open loop and a totally separate issue. If I were
you I'd tune for open loop stoich and then use closed loop
to put the steady stare mixture where you want it, on the
highway. As far as PE goes, factory tunes are over-fat to
begin with (I expect, so as not to pay a lot of warranty
on blown up motors). It's unlikely you want even as rich as
stock, let alone richer.