Don't get me wrong here, I don't disagree with Bob that custom PCM
programming is the best route, but consider that it's for your specific
vehicle, the Dyno time, and cost of the PCM programming...and you can
hit $800+ in a one-day tuning session (easily). $400+ for PCM
programming + Dyno Time (minimum 2-4 hours with A/F).
If you modify the MAP signal (as in this case), yes...the PCM will try
to correct itself to keep itself within factory parameter. Under Closed
Loop operation, the PCM wants to keep things at a 14.7-15.0:1 ratio.
However, if you're running larger injectors, bigger cam, modified heads,
etc., the MAP input signal (vacuum signal) and fuel output (O2) is
altered already and the PCM will try to compensate...sometimes too much
and can go out of range. This is where the APEXi unit (and a few others
similar to it) comes in handy. You can modify the signal to the PCM and
get it close to 14.7-15.0:1 again without having to reprogram. This
way, and under Closed Loop operation, the PCM stays happy. Sure, there
will be a little adjustment on the PCM's side, but this is just to keep
things ratio within the 14.7-15.0 ratio. In general they work very well
but there are cases where compression, cam profile, vacuum and other
custom engine build-up factors put you out of the realm of readily
available (and budget oriented) fuel tuning devices and you may need to
consider either aftermarket programming and/or aftermarket programmable
piggy-back (or stand-alone) systems.
Another simple way of looking at things:
Input = What the PCM is "reading" from the sensor(s).
Output = What the PCM is "telling" the fuel/timing to do based on the
inputs
Under Open-Loop operation, O2 is ignored and reverts to a baseline. You
can adjust things without any problems at all.
This was verified with a Dodge Master Tech (and not just some paper-work
certified tech but also a fellow racer with a modified '01 Dodge Ram),
with an internal (PVO) Dodge source, and two "Chip" manufacturers (one
being a Superchips tech).
- Bernd
-----Original Message-----
From: owner-dakota-truck@bent.twistedbits.net
[mailto:owner-dakota-truck@bent.twistedbits.net] On Behalf Of Bob Mankin
Sent: Thursday, May 29, 2003 11:53 PM
To: dakota-truck@dakota-truck.net
Subject: RE: DML: Re: RE: Re: Re: Re: Re: Superchips Dyno Results
Ron, if you'll retrace the thread, I was asking that you dyno before and
then a few weeks after so we all might learn something from the
exercise, myself included. Trying to be objective here.
Not sure why Bernd feels the need to so strongly defend the product
based on his word alone. I'm simply looking for hard data. As I said, I
personally believe there are better options out there but I won't make
assumptions on your motivations for the purchase decision.
Good luck with the box.
Bob
This archive was generated by hypermail 2b29 : Fri Feb 06 2004 - 11:46:22 EST