Tiger2o69

iTrader: (16)

So with me running closed loop can I target 15.1 under engine--fuel control--general--stoich afr? And that would make me run leaner right.. I assume it would also keep my ltfts right.

I would then have to change my pe by the same percent I assume.


Im sure there is a down side right?

Tiger2o69

iTrader: (16)

Is there another table I could make some area's richer w/o the fuel trims adjusting for it?

Patrick G

iTrader: (14)

I've got mine around 15.0-15.5 A/F ratio in some low load, low rpm situations. MPGs picked up slightly, but not as much as I wanted. I need to spend more time with the wideband and see about going leaner in more cells. I like the option a lot though.

JimMueller

iTrader: (9)

I'm using the pseudo lean cruise via OLSD as well. My MVPI Pro is working better than the serial version of HPT, so I'm spending some more time on the VE tables. But I log my RPM, MAP, ECT, VSS as a baseline to try to find conditions in the chart to translate to the OLFA table.

My idle is between 47-50MAP. Right now I'm commanding a max of 15.5 AFR between 20-45 MAP, and between 176-212 ECT, with the boundaries smoothed in.

smit2732

iTrader: (12)

closed loop trick???
replace both front NB's with wideband o2's that can simmulate NB o2's. (LC1)

On the inovative lc1(What I use), one of the outputs is set up to simmulate the factory NB o2 sensor. You can adjust the settings to fool the pcm. You will need one for each side.
Normally, when cruising around in closed loop, The pcm regulates the fuel to maintain a 14.7AFR. Your o2 sensors measure the exhaust AFR and feeds a mv signal back to the pcm. The pcm knows that 450mv
from the O2 sensor equals close to 14.7afr. What if you change the programmable output of the wideband sensors? Instead of outputting 450mv at 14.7afr, rescale the LC1 settings to produce 450mv at 16.1afr. something like this:
14.7afr= 410mv instead of 450mv
16.1afr= 450mv instead of 492mv
17.5afr=489mv instead of 535mv

by doing this you fool your pcm. It thinks its regulating 14.7afr because it see's 450mv from each sensor. But, 450mv no longer equals 14.7 instead, 450mv equals 16.1arf and you are now using 10% less fuel.

now you must increase your pe enrichment x rpm table by around 10%

wait4me

iTrader: (10)

Efilive custom os 3, you can command any air fuel ratios at any point in the rpm and kpa. No tricks needed.

Rob

iTrader: (6)

I used to run up to 16.7:1 with the stock cam without any problems. Since doing the cam change, I can't go any higher than 15.5:1 or it will start surging/bucking. So I'm running right at 15.3:1. Helps some but not as much as it used to. I see about 2mpg better than without where as before I could get up to 4mpg better with the stock cam.

I'm doing it via lean cruise since the goat can do it

onecamaro1

Hey guys, i changed my stoich to 15.5 and drove 3/4 of a tank, and have noticed no side effects. Just did some WOT runs, and it still seems strong. No pinging or knocking.

MSUGTP

So after adjusting the values in the Commanded AFR Table, I'd think you would need to go and adjust your Primary VE Table to account for the leaner condition, correct? Bring'n this thread back from the dead!

jimmyblue

iTrader: (11)

Before worrying about what you command, worry about whether
what you command (including especially, 1.000 EQ closed loop)
is what you get.

The most recent vehicle I worked on, abnormal though it is, was
showing ~ 13:1 by the wideband in closed loop with the O2s
switching all nice and even (to the eye).

Pushing down the O2 switchpoints to 300mV made it run around
14.5 - 15:1 AFR. If I had pushed them down more I could have
gotten "lean closed loop". But this is a supercharged max effort
race toy that happens to be street driven so I wasn't looking to
get anything more than sensible fuel trimming behavior off it.

Get this cleaned up on your setup and see what the wideband
says you obtain on the highway. You may get what you're
looking for. You just need to be sure it doesn't result in kooky
fuel trimming.

macca_779

100% agree Jesse. In Australia we have Lean Cruise available to us but when I use COS3/5 I don't even bother with it as I can just command my lean values in my primary fuelling table. The only real advantage Lean cruise has is that it can be speed enabled.. But in saying that, I've never had any problems doing it in the COS at any speed.

Frost

iTrader: (45)

When I see this behavior, I usually tell the owners to replace the O2s (if they have some mileage on them) and if they do, and the results are the same, then I do some switchpoint work. In more than 2 out 3 cases though, it seems to be the O2s. It's not always though.