Setting up closed loop fueling
 

Hello
How much setting up is required to run closed loop? Is it something that should be setup by a tuner or is it easy and safe like cold start etc?
The reason im asking is my car has a 20B and is mainly used for highway cruising. I know that it will never be good on fuel but, I would like it to be better for cruise and Idle. It has a wide band o2 sensor setup on it.

step one is to get the normal maps right, and close to the target AFR. so the car needs to drive well, and have a consistent AFR in the cruising range.

then you can turn on the closed loop. you can do closed loop on a not tuned very well map, but it can drive weird, as its supposed to make small changes in fuel.

anyways, factory style setup would have closed loop ON between 1500-3200, under about 25-30% throttle. the factory emissions tune, does closed loop @14.7:1 afr, but without a cat you can go a little leaner.

we found with the 20b, 70mph is over 3200rpms and the factory ecu is out of closed loop, runs rich, and gets like 10mpg. with the haltech you can leave it on later, or just tune the map leaner, and keep the mileage

the factory idles the engine fairly rich, since a misfire = high emissions, and they just add more air with the airpump.

if you have no emissions to worry about, you can go leaner with the idle, but it takes some playing. cirspeed has posted plenty of info about how to tune a leaner idle, in the 13:1-13.5:1 area

my old e11/20B FC would got 19.9mph on its long trip to sevenstock, which is like 1000miles round trip.

i should add we just tuned the cruise area (1500-3500, in vacuum) for about 14.4 afr with the cat and about 15-15.5 without

and actually now that i'm thinking about it, the e11 wouldn't read the o2 sensor so we couldn't use closed loop

It's very simple! Anybody can do it. Just need to figure out the narrowband's O2 sensor stoic millivolts reading. O2 loop setup takes about 10 minutes or so. Pretty easy and is done while cruising down the highway.

B

before running closed loop, have your mixtures spot on. the closed loop will only add or minus a maximum of 25% fuel.

25% is a LOT. You'll need your mapping to be much closer than that. Closed loop should never need to pull more than 5% to maintain mixture. Also, notice I said pull. You'll always want to setup your base maps and closed loop control to pull fuel to maintain the desired mixture. In case there is a failure of the O2 sensor, you never want to depend on closed loop to add fuel.

+1, that is how the stock ecu is too