Narrow band o2 sensor location

[Brickhouse]

I have a interesting question. How far down should my narrow band o2 sensors be? Would moving them farther downstream help with a lean condition? They are currently right on my collectors about 4-6? post heads with Ram exhaust. My wideband is 20? downstream the collector per installation instructions. I have run through all of the tuning cycles. MAF and VE separately multiple times with my wideband through the monitor. The math for my wide band calls for voltage +8 but this reading was lower than the gauge display so I made the 2 match with +9. So everything is dialed in 1-2% and when I go closed loop the ECM is adding 10% to make stoich. If I go with the recommended +8 I would be reading even more rich on the wide band. I?m getting horrible MPG and always have with this engine swap. Any thoughts would be greatly appreciated. Thanks. You

[5FDP]

Moving them further down the exhaust stream shouldn't really make a difference. If there is no exhaust leaks or vacuum leaks before the sensors it's going to read the same things.

On some setups even when tuning with a wideband it will be lean/rich when going back to closed loop. On theses you will just need to hand scale the MAF/VE to bring the fuel trims back closer to zero. If the trims are showing -10% still, it could be as simple as highlighting the area in the MAF curve and VE table where it's cruising at and removing 3-4% worth of fuel and smoothing the table.

I wouldn't expect to gain a ton of miles per gallon fixing that but it's still worth doing. The engine size, tires, aero and how much rpm/speed you are pulling will effect fuel mileage more.

[Brickhouse]

Thanks for the response. 10mpg hwy is pretty bad. No exhaust leaks. Maybe just run a tank open loop. Long trims are 12-15% lean

[5FDP]

What's the whole setup?

Post the tune and logs if you want.

[Brickhouse]

It?s a GMC Savana 0411 ECM into a 85 Landcruiser. Dual exhaust no cats. I know I lose some MPG on my 33?s with 4:11 gears. Just don?t understand going through the entire wideband thing to go closed loop and be even 10% off seems like a big waste. Why toon at all? just leave it stock and let LTFT do all the work. Frustrating that everybody I talk to says I should get 16-18 just tooting around. Funny I get the same MPG towing our 4000 pound trailer as I do just driving around.