I recently installed the infamous AC AFS-74 O2 sensor, and just started taking some data logs today. I see that the sensor was up and running way before I had closed loop enabled. Currently enabling closed loop at 104F, but my "warm" timer is at 180sec. Cold timer is at 300 sec and 50F, and "hot" timer is 30sec at 158F. I am assuming the "warm" timer is used between 50 and 158F.

What I saw on my scans was closed loop kicked in at 180 sec, and the coolant temp was way higher than 104, like 149 or so. That would kind of depend on the outside temps, but it does heat up fast.

I was just wondering what you all are using for timers/temps to get get closed loop, with a heated sensor.

I am running 165 MAF, $6E ARAP based bins.

 

I set my three timers using the same heated O2 to 15, 30, and 45 seconds. I've also tried 10, 20, and 30 and they seemed to work fine as well.....

 

Well that is interesting, Vern. Fairly short timers. I did burn a new chip trying 30, 60 and 180 sec for the timers. My car rarely sees engine starts less than 40deg, so i lowered the cold temp down as well.

I was just thinking you should let it be in open loop at cold startup, just so it is a bit richer than when in closed loop. But you can allways experiment!

anyone else have any comments?

 

Like you said, an engine not up to temp might not like running stoich... so why force it?
I run a 300sec cold (5 min), 30sec warm, and 10sec hot.
I could turn down the warm temp but I see no reason for it. The idea is to build heat in the combustion chamber and piston top. Once that's done the engine should run at stoich... the sensor itself doesn't take long to warm up. Even cold it'll warm up rather quickly so long as you're not running a really rich mix... ask me how I know, lol.

 

All good points. Think I'll raise my timers up a bit.... Thanks!

 

So JP, you set the timers based on how long you think the engine needs to warm up, then go in closed loop. NOT based on how long it takes for the heated O2 to warm and activate. I wonder how long it takes to actually heat up the sensor. I bet it is longer than you think. With my WB LM1, you can see how long it takes to warm up. It takes like 25-30sec.

I suppose with the AFS-74, you could experiment with the hot timer, and take some scan data to see how long it takes to activate.

 

As long as the O2 is 600*F and producing a signal you can go into closed loop as soon as you like. I have my TBI going into closed loop after about 30 seconds. SOME OEMs have the O2 sensor heating up so quick that they have their cars going into closed loop about 10 secs after a cold start.

 

Correct. Example; my car HATES to run near stoich when it's less than freezing outside. I tried everything from the choke SA and the CTS SA, AE vs temp, nothing helped so I just left it in open loop longer and ran less timing. I did run the engine leaner but that was because my spark plugs were a step cooler than what was recommended. That turned out to be the sweat spot with this motor. I don't know how it effects engine warm up temps because I never bothered to time it but the thing warms up just as fast as before or so it appears.
It's a balancing act, only trial and error will tell you what your motor wants.
The good thing about stock f-body code is that even when in closed loop, you'll have PE mode to enrich the higher throttle openings. The problem is that the PE mode isn't triggered by the raising MAP, it's TPS based. For a warmed up engine I've liked using the TPS but in a cold motor in closed loop you would (assuming here) want MAP.
Just do whatever runs best and let me know what's working and what isn't.

 

That is interesting, JP. I dont run my car at much below 40degF. Right now I have my timers at 30 sec, 60, and 180. And the coolant temp to enable CL set to about 103F. What I have seen is that on cooler days, starting a cold engine, it takes longer than 60 sec to get the coolant up to temp. So that parameter determines when CL is enabled. But on hot days, like now, starting car in lot after work, the coolant gets warm quick, so I hit CL in 60sec. Kind of cool how how both constants can work against each other, but both doing the same thing, like a system of checks and balances.

The only other benefit I can think of getting to CL sooner would be to save fuel, since when you are in open loop, the AFR is generally richer, for intial warm up.