Hey guys,

I am confused.. My car does not always stay in closed loop.. Even AFTER it is warmed up. My understanding was that the ECM goes into closed loop once everything warms up (roughly after 2-3 mins of driving say). My car warms up to about 180* and then that's when the fans turn on, but sometimes even when it gets to around 180, the ALDL flags report it as being in OPEN loop.. I am confused?? Are the ALDL flags reporting this wrong, do I have a faulty Oxygen sensor? It is brand new.. So that wouldn't make sense. I did accidently spill oil down the heads and onto the header once, could that maybe be causing it? OR maybe because I have headers, the O2 sensor (I have a 1 wire) is just not warming up? I have Edelbrock Shorty headers.. They are not long tube so I thought they should be okay for a 1 wire..

Any thoughts? In the bin the closed loop temp is around 104* minimum temp.. So that doesn't make sense either..

It is possible the 02 sensor is not getting hot enought. Option is to move location of sensor or better yet to use a heated sensor...

Yes, a heated O2 sensor seems to be what is needed... Also, kinda off topic here, but is it normal that when I tune the BLM's for 128 in open loop, then in closed loop (when it rarely goes in) it throws it off to like 132+? How is that possible? Isn't it supposed to bring it back to 128 if it's 'off'?

I dont fully understand your question. You say not in Cl but in OL. OL no feedback from 02 sensor so no INT change occurs and therefore no BLM change is done. If in OL with WB02 you could tune OL based upon A/F you see and want. In OL it uses the VE tables as is. If you are seeing a short period of CL and see a 132 that is pretty close to 128(+or-4). If you expect to see 128 day to day hour to hour it may not happen. lately I have been doing more smoothening without regard to a 132 here there. VE table wont be lineear but will not show raw peaks/valleys. From 90 deg days in PM to 60 in morn you will see trends. I will run a warm environ .bin and a cool BLM .bin. as in summer-spring/fall.

So in OL, there is no way to see BLM's accurately?? I thought that the whole point was to Tune in OL first, then tune it more precisely in closed loop.!

What I meant was, I see myself running open loop 80% of the time it seems, I go back into open loop FAR too often (i'm not talking about WOT, just idle and part throttle). That's why I was having difficulty seeing changes in my readings then... I was changing MAF tables in open loop and i didn't see a change, until it went into closed loop! (Which was very brief by the way!).. So, the bottom line here, from what I understand, is that with my current situation, getting a 3wire O2 sensor, and tuning in CLOSED LOOP is the best way to do it?

Thanks..!

In OL BLMs show you nothing of value. I dont believe they ever change off 128. Do you see OL flag and changing BLM? I think not. I think in OL the NB02 still reads out in mvolts but that is of little help. I am SD not MAF so I hope this is correct!

you can tune in OL but it requires a WB. there is a specific OL table that is rpm vs vac/map and it is in A/F(14.5/1) for commanded values. I believe that table is used to tune OL with WB.

Stickies above are helpfull in learning more.

Wow.. I've read every sticky, every post related to 6E or MAF tuning and I've never seen that before.. Damn.. I was confused as to why it was not moving from 128.. Maybe it's cuz it goes into closed loop, so I started making changes and then the OL flag would go on and off at random! So this is what's making tuning the BLM's weird! Thanks for shedding some light on this one, 3 wire O2 sensor AND WBO2 sensor it is!