38 MPG in open loop?!

[abogart]

Since installing the TC lockup switch in the Corsica I noticed an erratic shaking/hesitation at lower speeds in 2nd and 3rd gears with TC locked. I must have never noticed it before because the TC must have a dampening effect on torque from the engine. This, combined with rough idle and occasional sputtering just after switching into closed loop (and the ECU throwing a P0140 code) tells me that the downstream O2 sensor is bad. I tried unplugging the connector for that sensor and... Nothing different. So I decided to try unplugging the other (upstream) O2 sensor to see if it would stay in open loop. Success! It doesn't even try to go into closed loop anymore. It doesn't even throw any codes, aside from the TC code that I always get now.

Once its warmed up, SG reports that AFR creeps up to 14.7 at idle and deceleration, down to 14.2 under moderate load, and holds about 14.4 at 55mph cruise. I would have thought that I would see lowered highway MPG, but at least according to SG, I'm using slightly less GPH to maintain cruise speed. Also, the roughness is pretty much gone.

I'm wondering if my WAI has something to do with it. Makes me wonder what other mods might have more of an effect in open loop. I'll get a new O2 sensor when i get the money and see what happens to the MPG.

[Milwaukee]

Originally Posted by abogart

Since installing the TC lockup switch in the Corsica I noticed an erratic shaking/hesitation at lower speeds in 2nd and 3rd gears with TC locked. I must have never noticed it before because the TC must have a dampening effect on torque from the engine. This, combined with rough idle and occasional sputtering just after switching into closed loop (and the ECU throwing a P0140 code) tells me that the downstream O2 sensor is bad. I tried unplugging the connector for that sensor and... Nothing different. So I decided to try unplugging the other (upstream) O2 sensor to see if it would stay in open loop. Success! It doesn't even try to go into closed loop anymore. It doesn't even throw any codes, aside from the TC code that I always get now.

Once its warmed up, SG reports that AFR creeps up to 14.7 at idle and deceleration, down to 14.2 under moderate load, and holds about 14.4 at 55mph cruise. I would have thought that I would see lowered highway MPG, but at least according to SG, I'm using slightly less GPH to maintain cruise speed. Also, the roughness is pretty much gone.

I'm wondering if my WAI has something to do with it. Makes me wonder what other mods might have more of an effect in open loop. I'll get a new O2 sensor when i get the money and see what happens to the MPG.

Order from Rock Auto they cheaper.

On torque convertor lock. On Ford trucks forum they advised not lock torque convertor below 25 mph it will be hard on it.

What speed and rpm in 2 gear when you tried lock? The lower speed with TQ lock isn't good for transmission.


On my 2000 F350 diesel It only lock 4th gear not 1-3 gear. That how they made. Only one thing I wish it lock 3rd gear which I need badly.

[abogart]

Originally Posted by Milwaukee

What speed and rpm in 2 gear when you tried lock? The lower speed with TQ lock isn't good for transmission.

I usually lock it up at about 18mph in 2nd gear, which is about 1250 rpm. Then I hold it in gear until around 2000 before shifting again. I try not to let it get below 1300 rpm while accelerating. Occasionally I will drop it into 3rd at 25 and cruise at about 1050, but I have to unlock or downshift if I need any power because it will lug the engine if I give it much gas at that speed.