I'm going to be replacing my NTK 1-wire o2 sensor for a 4-wire AC Delco afs75 heated o2 sensor in the next couple days.

I was going to datalog and see how long it takes on a cold start for my o2 to start swinging and then change the closed loop timer to around that time.

Is it ok if they o2 is swinging, heated up, to run closed loop, if the coolant temp isn't warm? Lets say it takes the o2 25 seconds to warm up, and the coolant temp is still below 50* F could I just change the coolant temp enable to 30*F but leave the timer to 25 seconds? Or will this cause drivability problems or what?

Anyone know how long it should take a heated o2 sensor to warm up to working conditions??

Also, is there anything else in the bin that needs to be changed because of the heated o2?

Thanks!

-Tyler

 

I would think you would want a richer mixture when engine coolant <160 deg F. Car may not run right being so lean. On a cold motor fuel falls out of atomization so a richer mix is needed. Why not set min temp to enable CL at say 150 deg and see how that works for you? When I changed to a heated NB02 I changed nothng in my .bin. CL is enabled at 160F for me.

 

Did you notice any global changes in your o2 readings when you changed to the heated o2?

I just installed it this afternoon, the 4-wire afs75 AC delco inplace of a 1-wire NTK sensor.

I did a log before, and right after.

My blms and ints never went above 131 or below 123 with the NTK.

After a little burning off of the heated one. My blms went up to 137 and as low as 118 normal cruising. 0-30mph

I'm assuming it's because the delco one is much more accurate and updates at a higher speed?

I guess my tune wasn't as tight as I thought it was.

Stock ARAP puts the temp to enable CL @ 104*F
150* seems a little high, I would think that the sooner it gets into closed loop the better fuel economy will be.

It also has the Hot timer to 158* (50seconds) and Cold timer to 58*(300 seconds)

I'm going to try and lower the Hot timer to 25 seconds and the Cold timer to 100 seconds. Will see how it acts tomorrow morning.


Any thoughts?

 

Update or sampling rate is dictated by ECM - NBO is a passive device as there is no active electronics inside. If you recall voltage response of a typical NBO is a S shaped curve with slope going nearly vertical about 14.7:1 and flattening out as mixture moves away from stoichiometric point. No two manufactures of NBO's have exactly the same shape response curve. I would expect some voltage response differences between NTK and Delco when detecting the same exhaust mixture. 1 or 2 points in BLM is minor - I would not worry at this stage.

//RF

 

Car responded fine with lowering the enable temp to 80 and max warmup time of 100 seconds. Went into closed loop in about 2-3 minutes.