Did you also log rpm, map, coolant temp, and most important A/F (prob
via O2 voltage)? My guess is that a timer is involved both in cold
start and warm/hot start. I'd guess the cold start timer were a bit
longer but both well within the OBDII spec for how soon to go into
closed loop. I'm guessing the way the timer is used is by watching the
O2 voltage for when it moves off of full rich and crosses the 0.45V
threshold, and if the timer expires before this crossing, then flag an
O2 sensor MIL else go into closed loop when it crosses.
Thats my guess - thanks for playing 8) hopefully we'll all learn something.
Shane
Bob Tom wrote:
>
> I finally remembered to hook up the scanner on my 97 5.2
> when I went on an errand today.
>
> Preliminary test on a cold start and hot/fairly warm start showed
> the pcm going into closed loop after a 49 second countdown on
> the scanner. Air temp. was somewhere in the 60-70F. I've noticed
> this while at the track well no matter what the air temp. is or how
> hot/cold the coolant is.
>
> My gut feeling is that it tied to a time period for the heating
> element of the O2 sensor(s) to reach the temp. (figure escapes
> me at the moment ... 600F?) at which the narrow band sensor(s)
> will begin to put out reliable signals.
>
> I'll post if I see any different results.
>
> Bob
>
>
This archive was generated by hypermail 2b29 : Fri Feb 06 2004 - 11:46:54 EST