there is a thread running called "strange lean condition". it was suggested that a possibility was the NB02 sensor cooling off.

Quote: "With headers (sensor mounted down at the collector, not up by the outlet ports), a high-flow cat, and 3" cat-back, the ONE-WIRE sensor isn't kept hot enough at low load and low rpm. When the sensor cools off, the voltage drops, and the computer sees "lean." So it starts dumping in more fuel, trying to compensate."

as you are aware my VE tables have a ton of fuel in them 2400-3000 rpm and 35-50 map. VE learn kept adding fuel. ended up fudging/increasing BPW to keep under 100 in VE table. my NB02(bosch 4years old) is just behind header collector flange in ext pipe. ceramic headers. dual ext. other ext pipe is a mirror image with WB02 there.

think a change to heated GM 02 might show a diff VE table?

also, i just noticed in my EBL logs that i am falling out of CL cruising at 65-70 mph(14.5/1 on WB) with no load on engine. periodically the "CL flag" goes out and come back to CL in about 30 secs. what might cause that? happens past 3 logging sessions about 15 minutes into commute. no flag for DE-AE resulting at that point.

i will look at my EBL logs again. what specifically should i be looking at in regards to NB02 readings in log?

 

Dropping in and out of closed loop like that is the classic indication that you NEED the heated O2 sensor.

 

thanks. might that explain my VE tables needing megga fuel? i think my BPW is now 120-125 or so and should be 80-85.

funny i popping out of CL started just recently in my EBL logs?

car is stored now. will install the heated 02 and the fresh fuel filter to kill 2 variables.

 

Sounds like a good plan.

 

Ron,

I think you need a heated O2 sensor. However, if the ECM is going out of C/L, then (correct me if I am wrong RBob), EBL will ignore that particular
sample if you are using BLM to tune. Now the sensor may be cooling off but not enough to exit C/L. You might try widening the mv window for the O2 sensor exit in and out of C/L. Maybe they're too tight. But if the sensor is 4 years old, I would take the opportunity to just replace it with a heated one.

 

You can check the closed loop AFR against the WB sensor. This will show whether the NB O2 is skewing the learn results. With the dropping out of closed loop check that it is not from lean cruise (highway) mode. There is an indicator for that status.

If the O2 is becoming inactive that will drop the ECM out of closed loop. The NB O2 needs to transition below or above the 'stay in closed loop' values. This is either below the lower value, or above the higher value.

If it does not do this within the timeout period (typically around 20 seconds), the ECM will drop out of closed loop.

Ronny, I sent you an updated BIN. Let me know if you didn't get it.

RBob.

 

bin received thank you. wont run it till next season.

not highway mode. i believe it is disabled. is there a flag in whats up for HM? i dont recall seeing it? i think 02 is transitioning as you stated. i dont believe it is differrent than stock? but now that i think of it did i not change it to enrichen CL operation from 14.70 to around 14.30 or so? i think i did. i will look at the values in .bin later and post them with the WU values in log of when it fell out of CL.