Let me rephrase something to make it a bit more detailed...(and yes, you're
correct on the "not ALWAYS at 140-150" statement. The 140-150 range is a
general temperature that is required (among other variables) for Closed-Loop.
The reason for this is that an engine running at 90-100 degrees is still too
cold for reaching the proper 14.7:1 A/F ratio. Remember, colder engines
require more fuel (basically like a choke on an old Carb). Once the
temperature is within a certain range, and all other variable are also within
their range, Closed-Loop is enabled.
Yes, the O2's have to heat up but when you hit Open-Loop, even on a normal-temp
engine (warm), if you hit Open-Loop, the O2's are ignored.
Heheheh...we better slow down a bit Shane...I think we're getting some people's
brains to the point of no return. ;)
- Bernd
> Thanks Bernd - and I echo the same for you. Have to admit that I might have
> trolled a bit with the "bet" thing. I've had a customer piss me off already
today
> and shouldn't let those frustrations out here.
>
> > On the data, I have mine as well. From all the trucks i've played with
> > (tested), the O2 was not the determining factor for OPEN-LOOP. MAP, TPS,
and
> > Coolant Temp are the deciding factors. There's no way around that.
> >
> > ** Cold engine (cold temperature) = OPEN-LOOP
>
> Mostly agree here as cold is relative. For example, I can start my truck in
10
> degrees F on one day and on another day I might start it in 110 degrees F.
When
> the truck first starts - it will be in Open-Loop regardless of whether I
started it
> in 10 degree F or 110 degree F weather.
>
> > ** Warm-Up (driving to warm up the engine) - at 140-150 degrees, it kicked
into
> > CLOSED-LOOP
>
> This transition from Open-Loop to Closed-Loop may have actually happened - I
am not
> challenging this. A transition from Open-Loop to Closed-Loop ALWAYS
occurring at
> 140-150 degrees IS EXACTLY what I'm challenging. For example, if I started my
> truck in 10 degrees F one day - do I have to wait until the motor gets to 140-
150
> degrees before the transition? I think NOT. Compare this to if I started my
truck
> in 110 degrees F - it should transition very rapidly. This is NOT the case
though.
>
> My findings indicate that both trucks will transition at almost the EXACT
same time
> - give or take a couple of seconds. This is due primarily to the fact that
our O2
> sensors are of the self-heating variety. I can even tell you within a second
or
> two EXACTLY when it will transition by looking at O2 sensor voltage ONLY.
This
> works every time with NO exceptions.
>
> > ** Warm Engine (cruising) = CLOSED-LOOP
> >
> > ** Warm Engine (WOT) = OPEN-LOOP (starts at about 3/4 throttle to boot when
MAP
> > is right about 2"hg.)
>
> It looks like you have found the delta-TPS transitions - I agree they are
there.
>
> > I can simulate the TPS and MAP signals using some test equipment I have but
the
> > easiest test i've done is at a warm-idle (CLOSED-LOOP). I forced the MAP to
> > 3.8v and low-and-behold...OPEN-LOOP. (Didn't touch the TPS, IAT, CTS, or
O2.)
> > I also disconnected the rear O2 and checked the status (still warm-
> > idle)...check engine light but CLOSED-LOOP.
>
> It is true that a rapid change (delta) in TPS or MAP will induce a transition
from
> Closed-Loop to Open-Loop (and vice-versa). This is due to "driveability"
> concerns. Think of it like a carb's "pump-shot". Without that rapid delta-
TPS
> transition to Open-Loop (richer mixture) the truck would bog. There are lots
of
> these driveability transients happening all the time. When I talk about the
O2
> sensor causing the transition from Open-Loop to Closed-Loop - I am referring
ONLY
> to the cold-start condition and the FIRST transition from Open to Closed-Loop.
>
> You are right that there are lots of other transitions that are related to
> delta-TPS and delta-MAP (among others?) but I've only noticed an extremely
> consistent behavior at the initial cold-start transition.
>
> > Sure the FSM's have their definitions of OPEN/CLOSED-LOOP, but from what
i've
> > seen/tested...the O2's have little effect on switching to OPEN-LOOP.
> >
> > - Bernd
> I think Bernd and I can demonstrate how
> much info can be gleaned from a positive argument 8-)
>
> Latr,
>
> Shane
>
This archive was generated by hypermail 2b29 : Fri Jun 20 2003 - 11:58:47 EDT