Nice story, but not quite true. Couple of general things first
There are two general modes for the engine: Open Loop and Close Loop
* Open loop means that the engine controller (PCM) is ignoring the O2 sensor
and is relying only on the internal fuel curve for its calculations.
* Close loop means that the PCM is looking at the O2 sensor, and is making
adjustments to hold the air/fuel ratio at 14.7:1
There isn't a knock sensor on the Magnum engines.
There are 9 specific modes for the PCM
Ignition switch ON
- ignition is on
- open loop mode
- using MAP, coolant temp, TPS
Engine startup (cranking)
- starter active
- open loop mode
- using bat. voltage, coolant temp, crankshaft position, MAP, TPS,
starter motor relay
Engine warm-up
- engine not up to operating temperature
- open loop mode
- using bat. voltage, coolant temp, crankshaft position, MAP, TPS,
camshaft position, park/neutral switch (auto only), a/c
Idle
- engine up to temp and idling
- closed loop mode
- using bat. voltage, coolant temp, crankshaft position, MAP, TPS,
camshaft position, park/neutral switch (auto only), a/c, O2
Cruise
- engine RPM steady and at operating temp
- closed loop mode
- using bat. voltage, coolant temp, crankshaft position, MAP, TPS,
camshaft position, park/neutral switch (auto only), a/c, O2
Acceleration
- engine demand for power increased via rapid change in TPS, up to
temp
- open loop mode
- using bat. voltage, coolant temp, crankshaft position, MAP, TPS,
camshaft position, park/neutral switch (auto only), a/c
Deceleration
- engine under hard deacceleration (via TPS), up to temp
- open loop mode
- using bat. voltage, coolant temp, crankshaft position, MAP, TPS,
camshaft position, park/neutral switch (auto only), a/c, vehicle speed
sensor
Wide open throttle
- engine at WOT, up to temp
- open loop mode
- using bat. voltage, coolant temp, crankshaft position, MAP, TPS,
camshaft position, park/neutral switch (auto only), a/c
Ignition switch OFF
- engine off
The full list of PCM inputs is:
* A/C request
* A/C select
* Auto shutdown
* Battery temp
* Battery volts
* Brake switch
* CCD bus + circuits
* CCD bus - circuits
* Camshaft position sensor
* Crankshaft position sensor
* Data link to DRB
* coolant temp
* fuel level
* generator output
* ignition switch position
* intake manifold air temp sensor
* leak detection pump
* MAP
* oil pressure
* output shaft speed sensor
* overdrive switch
* O2 sensors
* park/neutral switch (auto only)
* power ground
* sensor return
* signal ground
* throttle position sensor (TPS)
* transmission governor pressure sensor
* transmission temp sensor
* vehice speed from ABS
Note that some of these are simply relayed to the instrument cluster and
don't affect PCM operation.
Craig
-----Original Message-----
From: Markram123@aol.com [mailto:Markram123@aol.com]
Sent: August 5, 1999 11:36 PM
To: dakota-truck@buffnet.net
Subject: RE:Subject: DML: How does the Dak monitor intake air
quantity/volume?
th magnum series of engines uses a very efficient and much more complex
computer than the "ford type maf system"
the way our computer works is it reads off the various sensors while under
different loads and rpm ranges...below 2500 rpm and at part throttle the
computer primarily relies on the oxygen sensor and the map sensor..above
2500 rpm at part throttle the computer relies on the oxygen sensor and the
throttle position sensor..at wide open throttle the computer goes into a
closed preprogrammed program and doesn't rely on the sensors other than the
knock sensors...it constantly makes air fuel adjustments off of these
sensors
and takes into account intake air temp coolant temp etc. among others..hope
this goes a little to explain how things work....
This archive was generated by hypermail 2b29 : Fri Jun 20 2003 - 12:15:40 EDT