Function
| Enable Parameter
| Result or Use
|
Decel
Fuel Cut-Off (DFCO)
|
|
| • | The catalyst temperatures may exceed maximum limits during extended
decel maneuvers. |
| • | When the criteria is met, the low pressure lock-off will be
cycled off to shut off all fuel and cool the catalysts.When the criteria
is met, the low pressure lock-off will be cycled off to shut off all
fuel and cool the catalysts. |
| • | DFCO turns off the LPL until mode is exited. |
|
Decel Open Loop
|
|
| • | The vehicle will operate in open loop as soon as a deceleration
is detected that meets the criteria. |
| • | The vehicle will transition into DFCO if this decel time reaches
30 seconds. |
|
Speed Limiting
| VSS > 97 mph
RPM > 3000
|
| • | Speed limiting is achieved by closing the MCV valve at 97 mph
and does not reopen until 94 mph. |
| • | The vehicle operates in open loop while in speed limiting. |
|
RPM Limiting
| RPM > 5500
|
| • | RPM limiting is achieved by closing the MCV valve at 5500 RPM
and does not reopen until 5475 RPM. |
| • | The vehicle operates in open loop while in RPM limiting. |
|
Fuel Switch-Over
|
| • | FSU Voltage < 1.75 Volts |
| • | Wide Open MCV (< 4500 RPM and 0.45 second
at WOT, 100 ms at idle or 2 seconds at crank) |
|
| • | The vehicle will switch over to gasoline if an OBD fault is detected,
if crank time exceeds eight seconds, or if a wide open MCV is detected for
the amount of time noted. |
| • | The FSU will cause a switch-over if voltage (indicating fuel
level) drops below 1.75 volts (4 136 kPa at 21°C
[600 psi at 70°F]). |
| • | The vehicle will not restart on CNG until voltage exceeds 3.00 volts
(7 583 kPa at 21°C [1,100 psi at 70°F]) The
vehicle will not restart on CNG until voltage exceeds 3.00 volts
(7 583 kPa at 21°C [1,100 psi at 70°F]). |
|
Open Loop
|
| • | OBD failure of both O2 sensors |
|
| • | Block Learn and EGO multiplier will both be disabled, and EGO
multiplier will be returned to 1.000. |
| • | Fueling will be based on the block learn table as it exists prior
to going open loop. |
|
Closed Loop
|
|
| • | For the vehicle to enter closed loop operation, the ECU looks
at the ECT at start-up and will hold off closed loop operation for 20-90
seconds, depending on temperature. |
| • | In addition to ECT time, the ECU will look for an HO2 sensor
switch and add an additional 7-35 seconds, depending on HO2 activity. |
|
Start Prime Pulse MCV
|
| • | Must exceed 100 RPM increase every 4 ms in order
to disable the pulse |
| The ECU will deliver a prime pulse after every complete ECU shutdown
(if the criteria is met) by opening the MCV wide open in order to aid
in starting.
|
Lock-Offs
|
|
| • | The ECU will open the HPL for 1 second after a complete shutdown
and a key-on sequence. |
| • | After a 25 RPM signal is received, the LPL and the HPL
will be opened as long as an RPM signal is present. |
|
Warm-Up Cycle
|
| • | ECT at key off > 70°C (160°F) |
| • | Delta between ECT at start and ECT at key off > 40°C
(104°F) |
| For diagnostic use only.
|
Gasoline Starts or Cold Start Strategy
| 10°F or every 100 starts
Will switch to CNG operation when the criteria below is met.
|
| • | Gasoline start strategy used for gasoline injector durability. |
| • | On gasoline start codes 58 and 41 run (while in gasoline operation).
All others are delayed until five seconds after switch-over occurs. |
| - | TPS open > 6% during 500 ms switch-over period. |
| - | % error desired gas to actual gas for 1.5 seconds. |
|
Code Types
| --
|
| • | Type A: Emissions related. One cycle to set the MIL and DTC. |
| • | Type B: Emissions related. Two consecutive driving cycles to set
the MIL and DTC. |
| • | Type C: NOT USED. Non-emission related. No MIL , but the SES
light will turn on. |
| • | Type D: Non-emission related. No MIL or SES light set. |
|
