I hope they don't bet on it...here's the facts:
There are 7 different modes (conditions) that are used (besides Key-ON and
Key-Off mode) and here's the list of what sensors are monitors and determine
the mode:
(1) Engine Start-Up Mode (OPEN LOOP)
Battery Voltage
Coolant Temp
Crank Position
Intake Air Temp
MAP
TPS
Starter Motor Relay
Cam Position
(2) Engine Warm-Up Mode (OPEN LOOP)
Battery Voltage
Coolant Temp
Crank Position
Intake Air Temp
MAP
TPS
Cam Position
Park/Neutral Safety Switch (Automatics Only)
(3) Idle mode (Once at Operating Temp: CLOSED LOOP)
A/C Select (if equipped)
A/C Request (if equipped)
Battery Voltage
Coolant Temp
Crank Position
Intake Air Temp
MAP
TPS
Cam Position
O2 Sensors
Park/Neutral Safety Switch (Automatics Only)
(4) Cruise Mode (CLOSED LOOP)
A/C Select (if equipped)
A/C Request (if equipped)
Battery Voltage
Coolant Temp
Crank Position
Intake Air Temp
MAP
TPS
Cam Position
O2 Sensors
Park/Neutral Safety Switch (Automatics Only)
(5) Acceleration Mode (OPEN LOOP)
A/C Select (if equipped)
A/C Request (if equipped)
Battery Voltage
Coolant Temp
Crank Position
Intake Air Temp
MAP
TPS
Cam Position
Vehicle Speed Sensor
Park/Neutral Safety Switch (Automatics Only)
(6) Deceleration Mode (OPEN LOOP)
A/C Select (if equipped)
A/C Request (if equipped)
Battery Voltage
Coolant Temp
Crank Position
Intake Air Temp
MAP
TPS
Cam Position
Park/Neutral Safety Switch (Automatics Only)
Vehicle Speed Sensor
(7) Wide Open Throttle - WOT (OPEN LOOP)
Battery Voltage
Coolant Temp
Crank Position
Intake Air Temp
MAP
TPS
Cam Position
Under conditions 1,2,4,5,6,7...the O2 Sensor is ignored by the PCM. Y
Yes, even in the FSM's..."During Open-Loop modes, the PCM receives input
signals and responds according to preset PCM programming. Input from the O2
sensors is not monitored during Open-Loop modes."
-----Original Message-----
From: owner-dakota-truck@BUFFNET.NET
Subject: Re: DML: Gas mileage to crap?
> -----Original Message-----
> From: owner-dakota-truck@BUFFNET.NET
> Subject: Re: DML: Gas mileage to crap?
>
> Just a guess but it sounds like the truck is never warming up enough. The
> comp
> is never getting out of closed loop mode.
>
> Doug Fedeli
As I've stated here many times - the tranisition to closed loop has NOTHING
to
do with temperature. I've seen several trucks transition into closed loop
with
ambient/outside as well as block/coolant temperature at less than 50 degrees
F
on many, many occasions.
The key (possibly only) component that the PCM uses is the O2 sensor voltage
to
determine when to transition into closed loop (during cold start).
Anyone want to bet on it?
Latr,
Shane
This archive was generated by hypermail 2b29 : Fri Jun 20 2003 - 11:58:47 EDT