Sounds like a plan.
I'll get some data logs from the DRB-III (and Co-Pilot).
- Bernd
-----Original Message-----
From: owner-dakota-truck@bent.twistedbits.net
[mailto:owner-dakota-truck@bent.twistedbits.net] On Behalf Of Shane
Moseley
Sent: Wednesday, August 27, 2003 7:42 AM
To: dakota-truck@dakota-truck.net
Subject: Re: DML: injectors (Ron - Now Shane)
Bernd D. Ratsch wrote:
>Shane,
>
>The DRB-III showed a 2003 model going into closed loop at right about 2
>minutes.
>
Very possible depending on how fast the O2 sensor heated up. And it's
within the time spec according to OBDII regs.
> I verified this with our Master Tech (20 years experience on these
>vehicles) and he did state that yes...the variable was changed from 160
>to 140 degrees (ECT) in 2001 for one of the factors determining Closed
>Loop.
>
20 years experience is meaningless in this case since OBDII hasn't been
around near that long. In fact, in many ways it can actually taint the
opinion of someone who has been doing things differently for that many
years.
> O2 sensors also come into play, but ECT is a main factor.
>
Think of it this way - suppose you have a vehicle that someone has
removed all O2 sensors from. You crank said vehicle while cold and
within about 2 minutes it comes up to about 170 degrees coolant temp.
Suppose it goes into closed-loop at this point. Wonder what the
loop-control variable is? The O2 sensor - and you don't have any.
Hmmm, what would it be controlling now? The point is that if the
decision to go into closed loop doesn't revolve largely around the
loop-control variable and it's validity, then its meaningless.
>(You can compare it to the choke on the old carbureted vehicles.)
>
This comment furthur proves my second point above...
>I can try to save some data files (or printouts) for you if you like.
>I've got access to most anything from the late 80's to current (NGC).
>
A copy of the OBDII regulations would have a section that talks about
when the vehicle should be in closed loop and how fast after a cold
start this should occur. Remember the goal - to minimize emissions...to
achieve at or near min BSFC... to be as close to 14.7:1 A/F at nearly
all times... closed-loop control achieves this and the regulations speak
on when this must occur.
Lets make it easy - all we really need is some other individuals to do
some unbiased testing with their scanners. Anyone out there have Alex
Peper's OBD-II scanner? If so - you could upload some logs for everyone
to see (and/or use the free download at obd-2.com to analyze in
real-time). Afterall, data is always better than opinion...
Latr,
Shane
>
>- Bernd
>
>-----Original Message-----
>From: owner-dakota-truck@bent.twistedbits.net
>[mailto:owner-dakota-truck@bent.twistedbits.net] On Behalf Of Shane
>Moseley
>Sent: Monday, August 25, 2003 8:48 PM
>To: dakota-truck@dakota-truck.net
>Subject: Re: DML: injectors (Ron)
>
>
>
>As some will remember, my results differ from these - I don't believe
>that closed loop is determined by temperature. My opinion is that the
>onset of closed loop is determined by the oxygen sensor being at a
state
>
>where reliable readings can be made. I make this assertion after doing
>some testing when I used to live in the mountains around Nashville, TN.
>
>With my scan tool connected and reading all variables in real-time, I
>cranked my truck up and went to work at least a hundred times with the
>scantool logging everything. From this data I learned that when the
>oxygen sensor crossed the 0.45 volt threshold for the first time (or
was
>
>it second, can't remember exactly) this marked the point when the
>system
>
>would transition from open loop to closed loop during a cold start.
>The
>
>data showed that it didn't have anything to do with temperature. I sat
>many times in my driveway in 0-15 degree weather watching the system go
>into closed loop with the ECT still in the "below 100" degree range.
In
>
>fact, on a cold start (any weather condition) by looking at NOTHING but
>an A/F gauge I can tell you exactly (within +- 1 second) when it will
go
>
>into closed loop. Try that with temperature. Someone with a scantool
>in a cold area needs to check this out and report their findings.
>
>Peace!
>
>Shane
>
>
>
>
>
This archive was generated by hypermail 2b29 : Fri Feb 06 2004 - 11:46:54 EST