RE: Thought to ponder....

From: Ronald Wong (ron-wong@home.com)
Date: Sat Feb 24 2001 - 23:35:08 EST


This has to be a Zimmer question. He's actually the one that digs into the
programs. Besides he has the source code, at least for the Mopars.

Ron
00 PB SLT QC 4X2 5.9 46RE 3.92 LSD
For modifications see my DML Profile (URL follows)
http://www.twistedbits.net/WWWProfile/dakota/Kw9pV1EkFeOYY

-----Original Message-----
From: owner-dakota-truck@buffnet.net
[mailto:owner-dakota-truck@buffnet.net]On Behalf Of Bernd D. Ratsch
Sent: Saturday, February 24, 2001 8:21 PM
To: dakota-truck@buffnet.net
Subject: DML: Thought to ponder....

Ok...i've had several people ask me what the custom programmed PCM's do (for
Supercharged applications). Otherwise known as a "Blower Flash" or "Blower
Program".

Here's why i'm wondering if they really work:

The problem with the 1-BAR MAP sensor (with a Supercharger) is that it can't
read boost. When you first start your engine, the MAP sensor sends a
initial voltage reference to the PCM which designates "0". This can be
anywhere from 4.3 - 4.7v. What happens to the MAP sensor under boost is
that it sends more than 4.7v to the PCM...literally "freaking it out"
(sometimes up to 4.9v). Since the PCM doesn't understand boost and the MAP
voltage is above "0", it translates this to 30.8" vacuum instead. Anything
above the initial MAP reference is considered high vacuum by the PCM. So
how they get around this is beyond me. Programming wise, it's pretty much
impossible unless they use a 2-BAR MAP Sensor instead...which they don't
do...or have found somehow to add some lines of code to the PCM that watches
the MAP voltage. If it's above the initial reading then how do they add the
logic to a simple reference table that tells the PCM otherwise.
??????????????? Hmmmmmm..........???????????

Mike (Leach), Ron (Zimmer), Marty (KRC)???? Well?

- Bernd



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