thanks. this is the kind of stuff I like to read. most of the carbage on this
list gets deleted by me.
-=Mike
Ronald Wong wrote:
> Ok, sorry, pardon my ignorance. What I said before is not entirely true. I
> know, Steven, you hate it when I do that. Let me respond before you figure
> it out or at least before you can respond. E-mail server's from @home still
> suck so timing is not always correct on these responses.
>
> "Open loop" occurs during the following times:
>
> 1) Ignition switch (key-on) mode
> 2) Engine start-up mode
> 3) Engine warm-up mode
> 4) Acceleration mode
> 5) Deceleration mode
> 6) Wide open throttle mode
>
> "Closed loop" occurs during the following times:
>
> 1) Idle mode
> 2) Cruise mode
>
> It is true that there are fixed tables in the PCM for air/fuel ratios and
> emission controls. There are also engine timing tables. These tables are
> used in both open and closed loops in different ways. In all cases, there
> are many input sensors that supply information to the PCM. The only sensors
> that are ignored in "open loop" are the O2 sensors. That's because the
> emission controls are not used during this time because enriched mixtures
> are generally needed. This means that the data tables and programming is
> used in all cases based on input from a lot of sensors, O2 just being two or
> three of them depending on the engine you're running. When in "closed loop"
> the PCM attempts to adjust your air/fuel ratio to 14.7/1. This is supposed
> to be ideal for emissions. The assumption by the automotive engineers is
> that you're in "closed loop" most of the time. This is probably not the
> case with DML people.
>
> This is getting long, huh? Well, I'm not done yet because it's not fair to
> just tell part of the story. Each of the six "open loop" modes causes
> different things to happen. It's not just "open or closed" Those different
> modes in the "open loop" have different effects on your engine and the PCM
> responds accordingly. Since not too many people are interested in any mode
> that doesn't have to do with performance I will only go into that detail.
>
> Acceleration mode: The PCM recognizes this by an abrupt increase in MAP
> pressure or throttle position. Injector pulse width is increased in
> response to this condition.
>
> WOT mode: The PCM receives input from the following:
>
> 1) Battery voltage
> 2) Crankshaft Position Sensor
> 3) Engine coolant temp
> 4) Intake manifold air temp sensor
> 5) MAP sensor
> 6) TPS
> 7) Camshaft position sensor
>
> The PCM increases the amount of fuel by adjusting the pulse width ignoring
> the O2 sensor readings. Timing adjustments are made by the PCM at this time
> also.
>
> Basically, what all this boils down to is this. The PCM tables are still
> used, Jet or no Jet. It seems the Jet or Hypertech, fools the PCM by
> presenting different or false sensor inputs to the PCM. Based on the
> instructions for the Jet module, it is installed on the plug that has the
> inputs to the PCM.
>
> In my quest for information I am trying to get a hold of the timing tables
> that are in the PCM, both stock and HP. I will let you know when I get it.
>
> Great reading, huh?!
>
> Ron
> 00 SLT QC 4X2 5.9 46RE 3.92 LSD
> For modifications see my DML Profile
>
> -----Original Message-----
> From: owner-dakota-truck@buffnet.net
> [mailto:owner-dakota-truck@buffnet.net]On Behalf Of Jack Hilton
> Sent: Tuesday, October 24, 2000 2:04 PM
> To: dakota-truck@buffnet.net
> Subject: Re: DML: Re: Re: Jet Chip Group Buy
>
> Well, all the JET does is intercept and modify readings from the sensors.
> When the truck is at WOT it goes into Closed-Loop and reverts back to the
> static data tables burned into the SBEC , so it doesn't even look at the
> sensors.
>
> Jack
>
> "Steven T. Ekstrand" wrote:
>
> > | Yeah, but the biggest problem with a JET module is that it only effects
> > | Part-Throttle performance , *not* WOT.
> >
> > Jack-
> >
> > I didn't know about this one? It only works in "open loop" operation???
> >
> > -STE
-- -=Mike Kuriger 1991 Isuzu Impulse RS 1.8 2000 Dodge Durango SLT 4x4 4.7 http://www.isuzu-mods.com http://www.twistedbits.net/WWWProfile/dakota/NgFQdD9vkNHNg
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