US005415145A
United States Patent [19]
[11]
Letcher et a1.
[45]
[54]
[75]
START FUEL DECAY FOR A FLEXIBLE
5,119,671
6/1992 Kopera ................................ .. 73/116
5,142,479
8/1992
Poitier et a1. . . . .
. . . . . .. 123/491
5,150,683
9/1992
Depa et a1. . . . . . .
. . . . . ..
John E. Letcher, Chelsea; Stuart M.
5,163,408 11/1992
Nemoto . . . . . . . . . . .
. . . . . .. 123/491
Davis, Bloom?eld Hills, both Of
5,186,449
2/1993
Kitajima et a1. . . . . .
. . . . . .. 123/491
Mich.
5,205,255
4/1993 Yamagata et a1.
5,289,808
3/1994
Inventors:
_
[73] Ass1gnee:
‘
-
_
Assistant Examiner-Thomas N. Moulis
Attorney, Agent, or Firm—Mark P. Calcaterra
Ma 4 1993
y ’
[57]
[51]
Int. Cl.6 ........................................... .. F02M 41/06
[52]
[58]
US. Cl. .................................................. .. 123/491
Field of Search ........ .. 123/491, 1 A, 478, 179.16,
123/491
_
[56]
..... .. 123/491
Primary Examiner-Henry C. Yuen
[21] Appl‘ NO" 57’247
Filed:
123/417
Takahashi et a1. ................ .. 123/491
Chrysler Corporatmn, Hlghland
Park, Mich.
l 1
May 16, 1995
FUEL COMPENSATION SYSTEM
_
22
5,415,145
Patent Number:
Date of Patent:
References Clted
ABSTRACI‘
_
_
_
_
A ?exlble fuel compensatlon System Including a method
of Start fuel decay- The Start fueldecay method interpo
lates decay rates based on the coolant temperature. The
decay rate is then subtracted from the decayed start fuel
pulsewidth until it reaches a predetermined value.
U.S. PATENT DOCUMENTS
5,027,779 7/1991 Nishiyama ........................ .. 123/491
12 Claims, 12 Drawing Sheets
230
232
/n
Run Fue/
Mode ?
Calculate Run Fue/ _
lnjeoz‘ion Pu/sew/o’z‘h Lie-2.36‘
,
.
Use Percent‘ Of Methanol 7'0
Look Up FFV Fuel C0mpen—__/_Z35
sat/‘0n From Table
,
Run Fuel lnjection Pu/sem'dth
= Run Fuel Injection Pu/se
width *(FFV Fuel- Compensation)
240
U.S. Patent
May 16, 1995
Sheet 1 of 12
5,415,145
10
ENG/NE
"/ 74
/
CONTROLLER
Z7
4
72
/
I
07715?
‘
A C TUA TOPS
FUEL
ENG/NE
SENSORS
"/15
['5
//v./£oro/?s
FLEX FUEL
SYSTEM
‘/ 20
LEI; - J- -
232
No
Yes
Calculate Run Fuel _
lnjecz‘l'on Pu/sew/a'fh --'-Z36
v
Use Peroenz‘ 0f Methanol To
Look Up FFV Fue/ Compen-_/"Z38
sot/‘on From Table
,
Run Fuel Injection Pu/sew/b'z‘h
= Run Fuel Injection Pulse
width *(FFV Fue/ Compensation)
/
v
240
US. Patent
May 16, 1995
Sheet 3 of 12
5,415,145
‘as
547 @
ls
Comb/he 7778 A-CURW
Eng/he Speed
14/70’ B-CURVE FZ/[L
FNR/CHMF/VT MUL 77PL/[RS
Above 28/5
RPM ?
4r
Multlo/y 771a Value By The/55
BARO FNRlCHMFA/T COMPEIVSA 770/V 4101 77/1/55?
‘y
Mu/t/jo/y The Product By _/-53
The [OR HVR/CHMENT
‘90
yes
Execute 77re Sub
rout/he: Inject/on Fuel
Pu/sew/dth Calculation
<
92
\
COMPFMS‘A 770/V MUL URL/ER
70
y
v
-Re—load A Copy Of 771e
/
'Base” Mu/trbl/er From RAM
Multljoly 777a Product By the AIR‘
4,
CHARCF TEMP mn/cnnnvr
Mum-p0, me Page" Mu/t/,'0//'er/94
COMPENSA 77OA/ MUL I7PU£R
_
+
72
Multiply The Product By The "/
771’RO77ZE LEAN-OUT FACTOR
4r
nun/p01 The Product By 777e ~/74
MAP LBW-OUT
\l/ 545701‘?
Mu/tloly The Product By The ._.-75
PART- THROTIZE cnn/cnusnr
By 7776 ,gANK-Z ADAP?l/E '
96 uruonr FACTOR
q,
Mun/p0, 77,9 Product By 7775
BANK-2 OZ CONTROLLER FACTOR
4,
BANK-2
Store ThePULSFMOll-l
?nal Value MUL
To TlPL/ER
1
95
,8
I00
Eng/ne Speed
FACTOR
.
4’
Multiply The Product By lhe ~e-78
HOT FUEL ENR/CHME/VT FACTOR
4,
Store A Copy Of The "Base" "/80
Mu/t/plier To RAM
*lr
Multiply The “Base” Multrbl/er v.82
5y 7778 BANK-l ADAP?l/E
urnonr moron
702
Above 2875
RPM ?
Yes
Execute The Sub-
routine: Inject/‘on C'ue/
Pu/sem'dth Calculation
,
v
( 5w,- )
,04
+
uu/tlp/y n7? Product By The
+194
BANK-4 02 co/vmourn moron
"
Store 777e F/no/ Value To 777e
-’85
BANK-l PULSEMOTl-l MUL 77PL/FR
l________
Eli;
:L
-
US. Patent
May 16, 1995
Sheet 4 of 12
Subrout/ne /n/ect/'on Fuel
Pu/sew/dth Calculation
5,415,145
702
At WOT
I74
708
I
V
Subtract 777a WON-W07 MAP
OfTS‘FT” From 7779 AVERAGE MAP
?6\_ 'MuliIp/y
. 777a t.
DIfference By
. 777a Y
Mu/t/p/y
O/fference By-’- 770
7716* NON-W07’ K-FACTOI?
778
/
Subtract 772a "W07 MAP OFF
SET” From 777a AVERAGE MAP
777a W07 K-FACTOP
‘l,
Malt/Ply 777a Product By 7776'
‘V
Mu/t/p/y 7726* Product By The
NON-W07‘ VOLUME7P/C [WC/[N67
W07’ VOL l/MEIP/C EFHC/E/VQ)’
v
(‘I 72
Add To 777a Product 777a BAPOMFR/C COMPFNSA 770/V PL/L SEM0771’
720
Calculations
For Qmhder Bank
#07 Or #02
p
724
1
*0’
v
728
I
Mu/t/[o/y 772a Sum By 7778 "BANK-
Mu/t/p/y 771a Sum By 777a "BAN/(
7 " PULSEM0771 MUL NFL/5‘?
2" PULSEM0771 MUL IIPUEP
1'
Jr
Store 777a Product To 7776
'25 ‘—' ‘BANK-l” BASE FUEL
Store 771a Product 70 The
'BANK-Z” BASE ma
PULSEMDIH
PUL 5EM0771
[
V
J
,
US. Patent
May 16, 1995
5,415,145
Sheet 5 of 12
768
Calculations
For Cy/nder Bank
$02
ls Engine
766
Speed Below
.3000 RPM
I
Load l77e 'BANK-l"
Load The "BANK-2"
BASE FUEL PULSEW/D77-l BASE FUEL PULSE/W0 TH
From inc Background
From 777e Background
Calculations
Calculations
777rott/e
I
A t W07
754
4'
4/
I46‘
L
740
y
Subtract llle "NON-W07 MAP
OFFSET” From ihe AVE/PAGE MAP
‘’
Maw/Multiply 777a 0/Tference By
l
Subtract ine "W07 MAP OFF
557'” From 77749 AVERAGE MAP
‘
t
742
Mu/tio/y 777a B/Tference By /
inc NON-W07’ /(—FA07'0P
ille W07 l(-FAOTOR
'
4'
Mu/tio/y 777a Product By lne
\l/
Mu/t/p/y lbe Product By 777a
NQN- W07 VOLUME72%‘ EFHC‘lEA/C)’
W07 VOLUMFlP/C [WC/ENC):
/
750
1
I
> V‘
(744
Add To 777a Product 1776 BARO
MEIR/C coupe/v54 no/v PUl5Elll077-L/752
754
Calculations
For C‘Mhder Bank
,{0/ 0r X02
[£102
_?
#107
758
I
v
Malt/ply lne Sum By 777e 'BANK-
Mu/tio/y ine Sum By 7776* "BANK
7 " PULSEM071? MUL llPL/El?
Z" PULSEM0771’ Ml/I. NFL/El?
Z
156
I
><
J,
Temporarily Store Fue/
Pu/sem'dth Value 7'0 RAM
Goto A (Fig. 6)
4’
_
760
5.
US. Patent
May 16, 1995
Sheet 6 of 12
5,415,145
CD
,
Calculate Me Map Acce/eratiom/ 770
Enrichment Pu/sewidth
_
,
Add 7'0 77Ie Value lhe lhrott/e
_
772
Acceleration Enrichment Pu/sewia’th
V
Multiply 777e Sum By lhe
Acceleration Enrichment ‘/ 7 74
Decay Mult/pl/er
V
Multiply 7726* Product By 7726'
Flex-Fuel Acceleration En- ../-775
richmen; Vaporization Com
pensation Multiplier
“
v
Add To The Product
____/775
lire Temporanly Stored
Fuel Pu/sewidth From RAM
/
Add 70 inc Sum lite
.p/jaa
A/S ENR/Cf/MEA/l‘ PULSEM0 Fl
v
Mu/t/ply 77).? Sum 5y
lazy-me Total Hex-Fuel
}'—_'—[
Pu/sewidth Multiplier
'
'
'
784
Calculations
For Cy’inder Bank
786
340
788
I
\
\-.S‘tore lhe Value To 777a
'PA/VK-l" H/EL PULSEM0777’
_
Store ?re Value To 777a
PAlVK-Z” H/EL PULSEM0771’
v
V
( EX/T )-/ '90
U.S. Patent
May 16, 1995
Sheet 7 of 12
( Decay
Start Feature
Fuel )
5,415,145
200
/
Save Last Start Fue/ Pu/se—__/.202
width 00 7st Pass Through
V
Calculate Run _
Fue/ Pu/sewidth /204
205
Set Injector
.
gmer Z'th
ecaye
Start Fue/
.
Eu/sew/dth
/
208
.
Decayed
Set Injector
Start Fue/ Pu/se——
77mer With
Math > Run Fue/
Run Fue/
.
.
Pu/sew/a'th
Pu/sew/dth
,
-
> 1‘
/n terpa
V/ate
Z210
“I. I
Decay Rate
272
v
Multiply
_
Decay Rate
274
\l/
Subtract Decay Amaunt
From Decayea' Start
‘
Fue/ Pu/sewia’th
‘Save Decayea’ Start
Fue/ Pu/sen/idth ‘
D/Isab/e Start Fue/_ fzgg
Decay Feature
V
224% Return )
E- Y‘
U.S. Patent
May 16, 1995
Sheet 8 of 12
5,415,145
Start Of
Initialization
302
ls Flag 7
N
o
/$ 1709 3
Set ?
Set ?
Methanol ) PredeN
emwned Methanol Boll-:91‘
0
303
)
Branch Around
Purge Corruption
58! ,4// Adaptive
Memory Cells <
Methanol Boll-Off
Cap lhreshold To
Predetermined
erature < Predeten
mined Methanol Bo/l-0/f
Methanol Boll-01?
Adaptive Memory
Reset Value
\
Km
V
' Set Hag ,y’lZ
Clear Hag ,fJ
V
V
1
Set Odometer Reading
.378
During Initialization =
591‘ odometer Read/"9
During lnltiah'zation = _ ,1305
Current Odometer
Set Flag ,f’l
Current Odometer
Z
J
326
v
Set All Adaptive Memory
Cells < Methanol Boil
0ft’ Cap lhresho/d l'o
Predetermined Methanol
Boil-Off Adap tive
Memory Reset Value
v
~----3;0
‘328
I
\ J
’ ‘
312
End Of Methanol
Boil-Off lnltialization
Current Purge I
Corruption
‘
\r
LEE-E
US. Patent
May 16, 1995
Sheet 9 of 12
Sz‘arz‘ 0f Run Mode
5,415,145
J30
‘ "/Vorma/ " Purge
Corrup z‘l'on
.
345
v
v
Use Methanol 50/7-
Use Normal
Off Adap five Memory
Adap five Memory
Upa’az‘e Rates For
‘
Upa'az‘e Raz‘es Far._,-335
340
No
< Prea'ez‘erm/nea’
Oxygen Sensor Ric/2 Fault
Maturation Disab/e
Hold O2 Sensor
Rich Fau/z‘
‘,342
Mafuraz‘ion 77mer
End Of 5017-025‘
/n Run Mode
344
US. Patent
May 16, 1995
Shee1_:10 of 12
350
Stan‘ 0f
Shutdown
J52
J54
' Clear F7ag #2
356'
ls (Current
00) — Odometer
Reading wring lnifia/izaflbn >
Mef/lanol 5’0/7-0/7r Feafure
Disa'm Constant
35a.“
350
- Clear Flag ,f/
\_
v
Clear H09 #6’
\
End Of
Shuz‘down
'
.
362
$.11
5,415,145
US. Patent
May 16, 1995
Start Hot Fuel
Enrichment Routine
Sheet 11 of 12
5,415,145
40a
402
LEA-5A
ls Coolant
Temp. At Start-Up
> A Calihratah/e
lrigger Paint
a
40.3
is shut
Off lime x7 >
404
V
405
Charge
Calculate l-lot Eue/
Enrichment Multiplier
Temp. At Start
Up > Trigger
Point ?
’
Disable Hot Fuel
Enrichment For This
408
ls
Engine
No
Speed < Cal/'
Entire Key-0n
hratab/e Trigger
(474
Point ?
470
Yes
ls
Manifold
Absolute Pressure
< Trigger
Point .9
Enrichment At
Minimum Allowed
US. Patent
May 16, 1995
Sheet 12 of 12
5,415,145
H0t Fue/
Enrichment At
Maximum Allowed
Correction
478
426
Have Enough
Cyl/nders Fired T0
Have Enough
Cyhna’ers Fired 7'0
Decrement H02‘
Fue/ Enrich.
lncrement Hot
Fue/ Enrich.
7
Yes
Decrement H02‘ Fue/
lncrement Hot Fue/
Enrichment /‘2{u/t/,'0/ier
Enrichment Mu/t/pher
L420
432
‘
v
»
[428
<__@
‘
430
r
‘
App/y Hot Fue/
Save Va/ue Of Hot I
Enrichment Multiplier
Fue/ Enrichment
70 Run Fuel
Mu/tial/er But 00 Not
Apply 70 Run Fuel
1
5,415,145
2
description ‘taken in conjunction with the accompany
ing drawings.
START FUEL DECAY FOR A FLEXIBLE FUEL
COMPENSATION SYSTEM
BRIEF DESCRIPTION OF THE DRAWINGS
5
BACKGROUND OF INVENTION
FIG. 1 is a schematic diagram of hardware for a
?exible fuel compensation system according to the pres
1. Field of the Invention
ent invention.
The present invention relates generally to fuel con
FIGS. 2 and 3 are ?owcharts of a method of ?exible
trol systems and, more speci?cally, to a ?exible fuel
fuel compensation control for the ?exible fuel compen
compensation system for an internal combustion engine.
sation system of FIG. 1.
2. Description of the Related Art
FIG. 4 is a ?owchart of a subroutine for the method
The automotive industry has been under increasing
of
FIGS. 2 and 3.
demands to develop an automotive vehicle that can
FIGS. 5 and 6 are ?owcharts of a method for execut
operate on different fuels such as gasoline and alcohol.
However, internal combustion engines must have selec 15
tively adjustable parameters for ef?cient combustion
when operating on the different fuels. One attempt to
meet this demand is an optical refraction index sensor
which utilizes the relationship between the percentage
of alcohol in a fuel mixture and the angle of light refrac
tion through the fuel mixture.
Currently, only methanol and ethanol types of alco
hols are viable fuel alternatives to gasoline since both
DESCRIPTION OF THE PREFERRED
It is, therefore, one object of the present invention to
provide a system of ?exible fuel compensation.
It is another object of the present invention to pro
EMBODIMENT(S)
25
Referring to FIG. 1, a ?exible fuel compensation
system 10 is illustrated in operational relationship with
an engine 12, such as an internal combustion engine, and
includes an engine controller 14, a plurality of elec
their current fuel control systems to accept alcohol
based fuels or gasoline/alcohol fuel mixtures.
SUMMARY OF THE INVENTION
FIG. 7 is a ?owchart of a subroutine for the method
of FIGS. 2 and 3.
FIG. 8 is a ?owchart of a subroutine for the method
of FIGS. 2 and 3.
FIGS. 9 through 11 are ?owcharts of a subroutine for
the method of FIGS. 2 and 3.
FIGS. 12A and 12B are ?owcharts of a subroutine for
the method of FIGS. 2 and 3.
are able to create a similar amount of power in spark
ignited, internal combustion engines. Thus, in order to
accommodate the ?uctuating supply of alcohol based
fuels, automotive vehicle manufacturers have to modify
ing calculations of FIGS. 2 and 3.
30 tronic fuel injectors 16, sensors 18 such as a ?ex fuel
sensor, a throttle sensor, a manifold absolute pressure
sensor, a coolant sensor, a charge temperature sensor,
shut off or down timer, etc., a ?ex fuel system 20, and
other actuators 21 such as a purge corruption system.
vide a ?exible fuel compensation system which has a 35 An example of a ?ex fuel system is disclosed in U.S. Pat.
No. 5,119,671 to Kopera and an example of a purge
greater pumping efficiency with gasoline and alcohol
based fuels.
It is yet another object of the present invention to
provide a ?exible fuel compensation system that makes
adjustments based on fuel blend vaporization.
It is still another object of the present invention to
provide a ?exible fuel compensation system that com
pensates for the high percent of oxygen found in alcohol
based fuels.
To achieve the foregoing objects, the present inven
corruption system is disclosed in U.S. Pat. No. 4,821,701
to Nankee, II et al., the disclosures of both patents are
hereby incorporated by reference. Preferably, the en
gine 12 has a plurality of spark ignited cylinders (not
shown) arranged in at least two banks such as Bank-1
and Bank-2 for a V-6 cylinder engine. It should be ap
preciated that the engine controller 14 includes a micro
processing, memory, input/output devices, bus lines,
45
tion is a ?exible fuel compensation system for an inter
etc. It should also be appreciated that the fuel injectors
16, sensors 18 and ?ex fuel system 20 are connected to
nal combustion engine. The ?exible fuel compensation
the engine controller 14 and communicate with the
engine controller 14 in order to control fuel injection
pulsewidths in the duty cycle sent to the electronic fuel
system includes a method that will compensate for the
differences in an engine pumping efficiency between
gasoline and alcohol based fuels. The system also in 50 injectors 16.
cludes a step which will adjust for the differences in
Referring to FIGS. 2 and 3, a ?owchart for a method
intrinsic vaporization characteristics between varying
of ?exible fuel compensation control is illustrated for
the ?exible fuel compensation system of FIG. 1. The
fuel blends. The system will further include a transient
fuel vaporization multiplier which adds extra fuel under
cold engine operation. The system also includes a step
to compensate for the natural lean bias which occurs
methodology starts in bubble 30 and advances to deci
sion block 32. In decision block 32, the methodology
determines whether the vehicle is con?gured for “?ex
with fuels containing a high percentage of methanol,
fue ”. This is accomplished by a de-select ?ag (calibrati
55
due to its high oxygen content.
ble). If so, the methodology advances to decision block
One advantage of the present invention is that a ?exi
34 and calculates a (B-curve) ?exible fuel vehicle (FFV)
ble fuel compensation system is provided for an internal 60 vaporization compensation multiplier to be described.
combustion engine. Another advantage of the present
The methodology then advances to block 36 and calcu
invention is that the ?exible fuel compensation system
allows the internal combustion engine to operate on
different fuels such as gasoline and alcohol or mixtures
thereof.
lates an (A-curve) FFV vaporization compensation
multiplier to be described. The methodology then ad
vances to block 38 and calculates a FFV fuel blend
65 energy content compensation multiplier to be described
Other objects, features and advantages of the present
in connection with FIG. 8. The methodology advances
invention will be readily appreciated as the same be
comes better understood after reading the following
to block 40 and calculates a transient fuel FFV vapori
zation compensation multiplier to be described. The
3
5,415,145
4
factor. The methodology then advances to block 84 and
multiplies the product of block 82 by a Bank-l oxygen
controller factor. The methodology then advances to
block 86 and stores the ?nal value of block 84 as the
methodology then advances to block 42 and calculates
a FFV pumping ef?ciency multiplier to be described.
The methodology then advances to block 44 and calcu
lates a total ?ex fuel pulsewidth multiplier by multiply
ing together the multipliers for blocks 34 through 42.
Bank-l pulsewidth multiplier. The methodology then
The methodology then advances to block 48 to be de
scribed.
In decision block 32, if the vehicle is not con?gured
for ?ex fuel, the methodology advances to block 46 and
sets all ?ex-fuel multipliers in blocks 34 through 42 to a
predetermined value such as 1.0. From blocks 44 and
advances to decision block 88 and determines whether
engine speed is greater than a predetermined speed such
as 2815 RPM. If not, the methodology advanced to
block 92 to be described. If so, the methodology ad
vances to block 90 and executes the subroutine Injec
tion Fuel Pulsewidth Calculation in FIG. 4 to be de
46, the methodology advances to block 48 and calcu
scribed to calculate an injection pulsewidth.
After blocks 88 and 90, the methodology then ad
lates an A-curve “time based” fuel enrichment multi
plier from a table stored in memory as a function of time
vances to block 92 and reloads a copy of the base multi
since start of the engine 12 and coolant temperature.
The methodology then advances to block 50 and multi
plies the value from block 48 by the A-curve FFV
plier of block 80 from memory. The methodology then
advances to block 94 and multiplies the base multiplier
by a Bank-2 adaptive memory factor. The methodology
then advances to block 96 and multiplies the product of
vaporization compensation multiplier from block 36
and temporarily stores the result in memory. The meth
block 94 by a Bank-2 oxygen controller factor. The
odology then advances to diamond 52 and determines 20 methodology then advances to block 98 and stores the
whether a throttle (not shown) of the engine 12 is at
?nal value of block 96 as the Bank-2 pulsewidth multi
wide open throttle (WOT) by a signal from the throttle
plier. The methodology then advances to decision block
100 and determines whether the engine speed is above
the predetermined speed. If not, the methodology re
sensor. If the throttle is not at wide open throttle, the
methodology advances to block 54 and calculates a
B-curve (coolant base) fuel enrichment multiplier from
turns or exits through bubble 104. If so, the methodol
ogy advances to block 102 and executes the subroutine
Injection Fuel Pulsewidth Calculation in FIG. 4 to be
a table stored in memory as a function of coolant tem
perature. If not, the methodology advances to diamond
56 and determines whether the throttle is closed by the
signal from the throttle sensor. If the throttle is closed,
described to calculate an injection pulsewidth. After
the methodology advances to block 58 and calculates a 30 block 102, the methodology returns or exits through
bubble 104.
B-curve (coolant based) fuel enrichment multiplier from
In FIG. 4, the methodology for the subroutine Injec
a table stored in memory as a function of MAP and
tion Fuel Pulsewidth Calculation is illustrated. The
coolant temperature. If the throttle is not closed, the
methodology advances to block 60 and calculates a
B-curve (coolant based) fuel enrichment multiplier from
another table stored in memory at a function of MAP
and coolant temperature.
From blocks 54, 58 and 60, the methodology ad
35
subroutine Injection Fuel Pulsewidth Calculation is
used to calculate the injection fuel pulsewidth for the
fuel injectors 16. Through block 102 of the subroutine
Injection Fuel Pulsewidth Calculation, the methodol
ogy advances to decision block 106 and determines
whether the throttle is at wide open throttle as previ
vances to block 64 and combines the A-curve and B
curve fuel enrichment multipliers from blocks 48 and 40 ously described. If the throttle is at wide open throttle,
the methodology advances to block 108 and subtracts a
either blocks 54, 58 and 60. The methodology then
predetermined WOTMAP offset from an average read
advances to block 66 and multiplies the value of block
64 by a barometric enrichment compensation multiplier
from a table stored in memory as a function of baromet
ing of MAP. The methodology then advances to block
110 and multiplies the difference of block 108 by a pre
ric pressure. The methodology then advances to block 45 determined WOT K-factor stored in memory. The
methodology then advances to block 112 and multiplies
68 and multiplies the product of block 66 by an EGR
the product of block 110 by a WOT volumetric effi
enrichment compensation multiplier from a table stored
ciency from a table stored in memory as a function of
in memory as a function of MAP and engine speed. The
MAP and engine speed. If the‘ throttle is not at WOT,
methodology then advances to block 70 and multiplies
the product of block 68 by an air charge temperature 50 the methodology advances to block 114 and subtracts a
predetermined non-WOT MAP offset from the average
enrichment compensation multiplier from a table stored
reading of MAP. The methodology then advances to
in memory as a function of air charge temperature. The
block 116 and multiplies the difference of block 114 by
methodology then advances to block 72 and multiplies
a predetermined non-WOT K-factor. The methodology
the product of block 70 by a predetermined throttle
lean'out factor stored in memory. The methodology 55 then advances to block 118 and multiplies the product
of block 116 by the non-WOT volumetric ef?ciency.
then advances to block 74 and multiplies the product of
From blocks 112 and 118, the methodology advances
block 72 by a predetermined manifold absolute pressure
to block 120 and adds a barometric compensation pulse
(MAP) lean-out factor stored in memory. The method
width from a table stored in memory as a function of
ology then advances to block 76 and multiplies the
product of block 74 by a predetermined part-throttle 60 barometric pressure to the product of either blocks 118
or 120. The methodology then advances to decision
enrichment factor stored in memory. The methodology
block 122 and determines whether the calculations are
then advances to block 78 and multiplies the product of
for cylinder Bank-l or 2, for example, by looking for a
block 76 by a hot fuel enrichment factor to be described
in connection with FIGS. 9 through 16. The methodol
flag. If the calculations are for cylinder Bank-l, the
ogy then advances to block 80 and stores a copy of the 65 methodology advances to block 124 and multiplies the
“base” multiplier of block 78 to memory. The method
sum of block 120 by the Bank-l pulsewidth multiplier of
ology then advances to block 82 and multiplies the base
block 86. The methodology then advances to block 126
multiplier of block 78 by a Bank-1 adaptive memory
and stores the product of block 124 to memory as the
5
5,415,145
Bank-1 base fuel pulsewidth. The methodology then
returns or exits through bubble 132.
In decision block 122, if the calculations are for cylin
der Bank-2, the methodology advances to block 128 and
multiples the sum of block 120 by the Bank-2 pulse
width multiplier of block 98. The methodology then
advances to block 130 and stores the product of block
128 to memory as the Bank-2 base fuel pulsewidth. The
6
From block 160, the methodology advances to block
170 and calculates a MAP Acceleration Enrichment
pulsewidth value based on rate of change of map and
coolant temperature. The methodology advances to
block 172 and adds a predetermined throttle accelera
tion enrichment pulsewidth value to the MAP accelera
tion enrichment pulsewidth value of block 170. The
methodology advances to block 174 and multiplies the
sum of block 172 by a predetermined acceleration en
methodology then returns or exits through bubble 132.
Referring to FIGS. 5 and 6, a methodology is illus 10 richment decay multiplier stored in memory. The meth
odology then advances to block 176 and multiplies the
trated to execute the run mode of the base fuel pulse
product of block 174 by a predetermined ?ex-fuel accel
width calculations of FIGS. 2 through 4. The method
eration enrichment vaporization compensation multi
ology is a crank interrupt routine that begins in block
plier stored in memory. The methodology advances to
134 and advances to decision block 136. In decision
block
178 and adds the fuel pulsewidth value of block
block 136, the methodology determines if the engine
160 to the product of block 176. The methodology
speed is below a predetermined value such as three
advances to block 180 and adds a predetermined AIS
thousand (3000) RPM. If the engine speed is below the
enrichment pulsewidth stored in memory to the sum of
predetermined value, the methodology advances to
block
178. The methodology then advances to block
decision block 138 and determines if the throttle is at
182 and multiplies the sum of block 180 by the total
wide open throttle as previously described. If the throt
?ex-fuel pulsewidth multiplier from block 44. The
tle is at wide open throttle, the methodology then ad
methodology advances to decision block 184 and deter
vances to block 140 and subtracts a predetermined
mines if the calculations for blocks 170 through 182 are
WOT MAP offset from the average reading of MAP.
for cylinder Bank-l or 2. If the calculations are for
The methodology then advances to block 142 and mul
25 cylinder Bank-l, the methodology advances to block
tiplies the difference of block 140 by a predetermined
186 and stores the value of block 182 to memory as the
WOT K-factor. The methodology advances to block
“Bank-1” fuel pulsewidth. If the calculations are for
144 and multiplies the product of block 142 by a prede
cylinder Bank-2, the methodology advances to block
termined WOT volumetric ef?ciency. The methodol
188 and stores the value of block 182 to memory as the
ogy then advances to block 152 to be described.
“Bank-2” fuel pulsewidth. From either blocks 186 and
In decision block 138, if the throttle was not at wide
188, the methodology enters bubble 190 and exits the
open throttle, the methodology advances to block 146
subroutine. It should be appreciated that the engine
and subtracts a predetermined non-WOT MAP offset
from the average reading of MAP. The methodology
then advances to block 148 and multiplies the difference
of block 146 by a predetermined non-WOT K-factor.
The methodology then advances to block 150 and mul
controller 14 uses the values of block 186 and 188 to
control the duty cycle to the fuel injectors 16.
Referring to FIG. 7, the methodology includes a start
fuel decay routine which operates simultaneously with
the beginning of the methodology of FIGS. 5 and 6.
The start fuel decay routine or methodology begins in
tiplies the product of block 148 by a predetermined
non-WOT volumetric efficiency. From block 144 and
block 200 and advances to block 202 and saves a last or
block 150, the methodology then advances to block 152 40 previous start fuel pulsewidth on a ?rst pass through the
and adds the product of either block 150 or 144 to a
routine. The methodology then advances to block 204
barometric compensation pulsewidth value from a table
and calculates a run fuel pulsewidth, according to
stored in memory as a function of barometric pressure.
FIGS. 2 through 6. The methodology advances to deci
From block 152, the methodology then advances to
sion block 206 and determines if the decayed start fuel
decision block 154 and determines whether the calcula 45 pulsewidth is greater than the run fuel pulsewidth of
tions for blocks 140 through 152 were for cylinder
block 204. If the decayed start fuel pulsewidth is greater
Bank-1 or 2. If the calculations are for cylinder Bank-l,
than the run fuel pulsewidth, the methodology ad
the methodology advances to block 156 and multiplies
vances to block 208 and sets a fuel injector timer with
the sum of block 152 by the Bank-l pulsewidth multi
the decayed start fuel pulsewidth. The methodology
plier from block 86. If the calculations are for cylinder
then advances to block 212 to be described.
Bank-2, the methodology advances to block 158 and
In decision block 206, if the decayed start fuel pulse
multiplies the sum of block 152 by the Bank-2 pulse
width is not greater than the run fuel pulsewidth, the
width multiplier from block 98. From either of blocks
methodology advances to block 210 and sets the fuel
156 or 158, the methodology advances to block 160 and
injector timer with the run fuel pulsewidth. From
temporarily stores the fuel pulsewidth value of either 55 blocks 208 and 210, the methodology advances to block
blocks 156 or 158 to memory.
212 and interpolates a decay rate of the fuel pulsewidth
In decision block 136, if the methodology determines
of blocks 208 and 210 versus the coolant temperature.
that the engine speed is not below the predetermined
The methodology then advances to block 214 and mul
value; the methodology advances to decision block 162
tiplies the decay rate of block 212 by a number of cylin
and determines if the calculations prior to block 136
der events since the start to run transfer has occurred.
were for cylinder Bank-1 or 2. If the calculations were
The methodology then advances to block 216 and sub
for cylinder Bank-1, the methodology advances to
tracts the decay amount from the decayed start fuel
block 164 and loads the Bank-l base fuel pulsewidth of
pulsewidth of block 208.
block 126 from memory. If the calculations are for
From block 216, the methodology advances to deci
cylinder Bank-2, the methodology advances to block 65 sion block 218 and determines if the decayed start fuel
pulsewidth is less than or equal to a predetermined
166 and loads the Bank-2 base fuel pulsewidth of block
130 from memory. From blocks 164 and 166, methodol
ogy then advances to block 160 previously described.
value such as zero. If the decayed start fuel pulsewidth
is less than or equal to the predetermined value, the
7
5,415,145
8
methodology advances to block 220 and disables the
start fuel decay routine of FIG. 7. If the decayed start
fuel pulsewidth is not less than or equal to the predeter
mined value, the methodology advances to block 222
and saves the decayed start fuel pulsewidth of block 216
to memory. From blocks 220 and 222, the methodology
cold/time enrichment pulsewidth which, in turn, modi
ties the base run fuel injection pulsewidth values before
enters bubble 224 and returns.
ology ?rst determines if the methodology for the engine
Referring to FIG. 8, the FFV fuel blend energy con
tent compensation multiplier of block 38 is illustrated.
This subroutine will adjust the run fuel injection pulse
width values for the differences in intrinsic energy con
12 is in the run fuel mode. If so, the methodology calcu
lates the run fuel injection pulsewidth previously de
scribed. The A-curve FFV vaporization multiplier is
the fuel is delivered. The A-curve FFV vaporization
multiplier is the interpolated multiplier from a 3-D sur
face of calibration values stored in memory of coolant
temperature versus the percentmethanol. The method
located from the A-curve three dimensional surface by
using coolant temperature and percent methanol as the
tent between varying fuel blends. The methodology
starts in bubble 230. From bubble 230, the methodology
interpolation parameters. This A-curve FFV vaporiza
advances to decision block 232 and determines if the
tion multiplier value is then multiplied by the run fuel
control methodology is in run fuel mode, for example, 15 injection pulsewidth previously calculated used to cre
by looking for a flag. If not, the methodology advances
ate a new run fuel injection pulsewidth.
to bubble 234 and exits. If so, the methodology ad
In blocks 40 and 176, the methodology will adjust the
vances to block 236 and calculates a new run fuel injec
transient run fuel injection pulsewidth value for the
tion pulsewidth based on FIGS. 2 through 6. The meth
differences in intrinsic vaporization characteristics be
odology then advances to block 238 and retrieves a 20 tween varying gasoline and methanol fuel blends. A
value for FFV fuel compensation from a two-dimen
multiplier term for transient run fuel injection pulse
sional table stored in memory by using a percentage of
width will modify the run fuel injection pulsewidths
methanol from the sensors as the interpolation parame
before the injections are delivered by the fuel injectors
ter. The methodology then advances to block 240 and
16. The methodology will determine the transient run
uses the value for FFV fuel compensation as a multi 25 fuel injection pulsewidth value from a three-dimen
plier to obtain a new value for the run fuel injector
sional surface of calibration values stored in memory
pulsewidth. This new run fuel injector pulsewidth value
is then sent by the engine controller 14 to the fuel injec
using coolant temperature and percent methanol as the
interpolation parameters. ‘The three-dimensional sur
face of calibration values represents the differences in
tors 16. The methodology next advances to bubble 234
and exits back to block 38.
30 vaporization characteristics between varying blends of
In block 42, to calculate the FFV pumping ef?ciency
gasoline and methanol at various temperatures. The
transient run fuel injection pulsewidth value causes the
mines that the routine is in the run fuel mode, for exam
run fuel injection pulsewidths to be increased with both
ple, by looking for a ?ag. The methodology will then
higher methanol content and colder temperatures.
calculate the run fuel injector pulsewidth value as previ 35
In blocks 84 and 96, the methodology determines the
ously described. Next, the methodology will look up
O2 cont-roller factor which compensates for the natural
the pumping ef?ciency multiplier from a 3-D surface of
lean bias which occurs with fuels containing a high
calibration values stored in memory. The 3-D surface is
percentage of methanol. The methodology adds four
based on 17 RPM intervals, 9 percent methanol inter
calibratible constants to the run fuel injection pulse
vals, and a multiplier within a predetermined range.
widths. These constants include the percent methanol
multiplier value, the methodology checks and deter
The pumping ef?ciency multiplier is then obtained from
the 3-D surface and multiplied by the run fuel injector
oxygen biasing trigger level, the rich primary limit
percent methanol bias, the lean primary limit percent
pulsewidth previously calculated to obtain a new run
methanol bias, and the cell mask which will dictate the
primary limit cells to be affected. The methodology
fuel injector pulsewidth. The methodology then returns
back to block 42 of FIG. 2.
In block 34, the methodology calculates the B-curve
FFV vaporization compensation multiplier to compen
sate for the FFV fuel blend vaporization. This multi
plier affects the cold enrichment pulsewidth which, in
45
determines if the percent methanol is greater than the
percent methanol oxygen biasing trigger level. Then,
the methodology applies the rich primary limit percent
methanol bias to the oxygen controller rich primary
limits as specified by the cell mask and also apply the
lean primary limit percent methanol bias to the oxygen
controller lean primary limits as speci?ed by the cell
mask.
turn, modi?es the base run fuel injection pulsewidth
values before the fuel is delivered. The methodology
?rst determines if the methodology for the engine 12 is
in the run fuel mode, for example, by looking for a flag.
Referring to FIG. 9, the methodology determines the
If so, the methodology calculates the run fuel injection
adaptive memory factor in blocks 82 and 84 according
pulsewidth value as previously described. The B-curve 55 to a methanol boil-off compensation initialization rou
component of the cold enrichment pulsewidth multi
tine. The methodology begins initialization in block 300.
plier is then located from a three-dimensional surface of
From block 300, the methodology advances to decision
calibration values stored in memory. The B-curve FFV
block 302 and determines if ?ag one (1) is set. Flag one
vaporization compensation multiplier value is based
(1) arms the purge corruption and MEOH boil-off. If
upon the coolant temperature (CLTEMP), the percent
flag one is set, the methodology advances to block 303
of methanol (PRMETH) in the fuel mixture and a multi
and branches around or disables the other actuators 21.
plier value. This BVAP3D multiplier value is then mul
The methodology then enters decision block 304 and
tiplied by the run fuel injection pulsewidth previously
determines if there are any adaptive memory (AM) cells
calculated to create a new run fuel injection pulsewidth
previously calculated.
In block 36, the methodology calibrates the A-curve
FFV vaporization multiplier to compensate for the
FFV fuel blend vaporization. This multiplier affects the
less than a methanol boil-off gap threshold. If there are
65 any adaptive memory cells less than the methanol boil
off gap threshold the methodology advances to block
306 and sets flag 2 which is the MEOH boil-off under
way ?ag. The methodology advances to block 308 and
5,415,145
sets an odometer reading during initialization equal to
the current odometer reading by the sensors 18. The
methodology then advances to block 310 and sets all the
adaptive memory cells less than the methanol boil-off
run mode.
Referring to FIG. 11, after the run mode routine of
FIG. 10, the methodology performs a methanol boil-off
compensation shutdown routine. The shutdown routine
methodology starts in block 350. From block 350, the
methodology enters decision block 352 and determines
if ?ag one is set. If ?ag one is set, the methodology
gap threshold to a predetermined methanol boil-off
adaptive memory reset value, such as -_|-.50% base fuel
pulse width. In decision block 304, if there are not any
adaptive memory cells less than the methanol boil-off
gap threshold, and after block 310, the methodology
advances to block 354 and clears ?ag two. The method
ology then advances to decision block 356 and deter
mines if the current odometer reading minus the odome
advances to block 312 and ends the initialization.
In decision block 302, if ?ag one is not set, the meth
odology advances to decision block 310. In decision
ter reading during initialization is greater than a prede
block 314, the methodology determines if flag three (3),
termined methanol boil-off feature disarm constant
stored in memory. If so, the methodology advances to
block 358 and clears ?ag one. The methodology then
the MEOH boil-off clean up ?ag, is set. If ?ag three is
set, the methodology advances to block 316 and sets all
of the adaptive memory cells less than the methanol
boil-off gap threshold to the predetermined methanol
enters block 360 and clears flag three. The methodology
then enters block 362 and ends the shutdown routine.
In decision block 352, if ?ag one is not set or in deci
- boil-off adaptive memory reset value. The methodology
next advances to block 318 and clears ?ag three. The
methodology then advances to block 312 previously
20
described.
In decision block 314, if ?ag three is not set, the meth
odology advances to decision block 320 and determines
if the percentage of methanol in the fuel from sensors 18
is greater than a predetermined methanol boil-off con 25
centration arm threshold stored in memory. If so, the
methodology advances to decision block 322 and deter
mines whether the engine temperature, determined by
sensors 18 is less than a predetermined methanol boil-off
arm temperature such as 10° F. If so, the methodology
advances to block 324 and sets ?ag one. The methodol
ogy then advances to block 326 and sets the odometer
reading during initialization, equal to the current odom
eter reading. The methodology, then advances to block
312, previously described.
In decision block 320, if the percent methanol is not
10
The methodology then enters block 344 and ends the
sion block 356, the current odometer reading minus the
odometer reading during initialization is not greater
than the methanol boil-off feature disarm constant, the
methodology advances to block 362 and ends the shut
down routine.
Referring to FIGS. 12A and 128, a methodology is
illustrated which determines the hot fuel enrichment
factor of block 78. This factor will eliminate fuel/air
control deviations which occur following short soak
hot starts and long soak hot starts. The methodology
starts in block 400 and advances to decision block 402 to
determine if the coolant temperature at start-up is
greater than a predetermined hot fuel enrichment en
able coolant temperature stored in memory. If the cool
ant temperature at start up is greater than hot fuel en
richment enable coolant temperature, the methodology
35 advances to decision block 403 and determines whether
the shut off time is greater than or predetermined value.
If not, the methodology advances to block 414 to be
described. If so, the methodology advances to decision
block 404 and determines if the charge temperature at
boil-off concentration arm threshold, the methodology 40 start up is greater than a predetermined hot fuel enrich
advances to block 328 and enables the other actuators
ment enable charge temperature stored in memory. If
21 for purge corruption and resets the adaptive memory
the charge temperature at start-up is greater than the
cells. The methodology then advances to block 312
hot fuel enrichment enable charge temperature, the
previously described.
methodology advances to block 406 and calculates a
Referring to FIG. 10, after initialization, the method 45 fuel enrichment multiplier. The fuel enrichment multi
ology executes the run mode of the methanol boil-o?'
plier is a function of the percent methanol in the fuel
compensation. The methodology begins in block 330
mixture, the charge temperature at start, and the time
and advances to decision block 332 and determines if
from start to run transfer. The methodology then ad
?ag one is set. If ?ag one is set, the methodology ad
vances to decision block 408 and determines if the en
vances to decision block 334 and determines if flag two
gine speed is less than a predetermined hot fuel enrich
is set. If ?ag two is set, the methodology advances to
ment enable RPM (I-IFERPM) stored in memory. If the
block 336 and uses a predetermined methanol boil-off
engine speed is less than the hot fuel enrichment enable
non-idle fuel adaptive memory update rate and a prede
RPM, the methodology advances to decision block 410
termined methanol boil-off idle fuel adaptive memory
and determines if MAP is less than a predetermined hot
update rate stored in memory. If ?ag two is not set, the 55 fuel enrichment enable MAP level stored in memory. If
methodology advances to block 338 and uses predeter
so, the methodology advances to decision block 412 to
mined normal adaptive memory update rates stored in
be described.
memory. The methodology, from blocks 336 and 338,
In decision block 402, if the coolant temperature at
advances to decision block 340 and determines if MAP
start up is not greater than the hot fuel enrichment
is less than a predetermined oxygen sensor rich fault
enable coolant temperature, the methodology advances
to block 414 and disables the hot fuel enrichment for the
maturation disable (MBO2FD) value such as 400 torr. If
so, the methodology advances to block 342 and holds an
entire key-on starting of the engine 12. In decision block
oxygen sensor rich fault maturation timer at its current
404, if the charge temperature at start-up is not greater
value. If not or after block 342, methodology advances
than the hot fuel enrichment enable charge temperature,
to block 344, and ends the run mode.
65 the methodology also advances to block 414 previously
In decision block 332, if ?ag one is not set, the meth
described.
odology advances to block 346 and performs a normal
Referring to decision blocks 408 and 410, if the engine
purge corruption where it will update purge free cells.
speed is not less than the hot fuel enrichment enable
greater than a predetermined methanol boil-off concen
tration arm threshold, or in decision block 322, if engine
temperature is not less than a predetermined methanol
11
5,415,145
12
interpolating a decay rate of a fuel injector pulse
RPM or MAP is not less than the hot fuel enrichment
width in the fuel injector timer versus a coolant
enable MAP level, the methodology advances to deci
sion block 416. In decision block 416 the methodology
temperature;
multiplying the decay rate by a number of cylinder
determines if a hot fuel enrichment value is at a prede
events since transferring from a start mode to a run
termined minimum allowed correction. If not, the meth
odology advances to decision block 418 and determines
if enough cylinders have ?red in order to decrement the
hot fuel enrichment multiplier by a predetermined rate
as a function of engine speed. If enough cylinders have
mode;
subtracting the decay rate from the decayed start fuel
injector pulsewidth;
determining if the decayed start fuel injector pulse
width is less than or equal to a predetermined
. fired, the methodology advances to block 420 and dec
rements the hot fuel enrichment multiplier as above
value;
disabling the start fuel decay method if the decayed
start fuel injector pulsewidth is less than or equal to
described. The methodology then advances to decision
block 422 to be described.
the predetermined value;
In decision block 412 the methodology determines if
this pass is the ?rst pass in the run fuel mode. If so, the
methodology advances to decision block 422 to be de
scribed. If not, the methodology enters decision block
saving the decayed start fuel injector pulsewidth if
the decayed start fuel injector pulsewidth is not less
than or equal to the predetermined value; and
adjusting the ?exible fuel being sent to fuel injectors
of the internal combustion engine based on the fuel
424. In decision block 424, the methodology determines
if the hot fuel enrichment is at a predetermined maxi
mum allowed correction. If so, the methodology ad
vances to decision block 422 to be described. If not, the
methodology advances to decision block 426 and deter
2. A method of start fuel decay adjustment to a fuel
mined rate as a function of engine speed. If not or after
determining if the decayed start fuel injector pulse
injector pulsewidth in the fuel injector timer.
injector pulsewidth in an internal combustion engine
capable of using a ?exible fuel, said method comprising
mines if enough cylinders have ?red in order to incre
the
steps of:
ment the hot fuel enrichment multiplier. If so, the meth
25
beginning a start fuel decay feature;
odology advances to block 428 and increments the hot
determining if a decayed start fuel injector pulse
fuel enrichment multiplier of block 406 by a predeter
width is greater than a run fuel injector pulsewidth;
block 428, the methodology advances to decision block
width is less than or equal to a predetermined
422.
value; and
adjusting the ?exible fuel being sent to fuel injectors
In decision block 422, the methodology determines if
the throttle is at wide open throttle. If so, the methodol
ogy advances to block 430 and saves the value of the
of the internal combustion engine based on either
the decayed start fuel injector pulsewidth or the
run fuel injector pulsewidth.
3. A method as set forth in claim 2 including the steps
hot fuel enrichment multiplier of blocks 420 and 428,
but it is not applied to the run fuel mode equation or to 35
the fuel injectors 16. If the throttle is not at wide open
of:
throttle, the methodology advances to block 432 and
saving a previous decayed start fuel injector pulse
applies the hot fuel enrichment multiplier of blocks 420
width; and
- and 428 to the run fuel equation and delivers additional
fuel to the fuel injectors 16.
The present invention has been described in an illus
calculating a run fuel injector pulsewidth prior to said
step of determining if the decayed start fuel injec
tor pulsewidth is greater than the run fuel injector
trative manner. It is to be understood that the terminol
ogy which has been used is intended to be in the nature
4. A method as set forth in claim 2 wherein said step
pulsewidth.
of words of description rather than of limitation.
of determining if the decayed start fuel injector pulse
Many modi?cations and variations of the present 45 width is greater than the run fuel injector pulsewidth
invention are possible in light of the above teachings.
includes the step of setting a fuel injector timer.
Therefore, within the scope of the appended claims, the
5. A method as set forth in claim 4 wherein said step
present invention may be practiced otherwise than as
of setting the fuel injector timer includes setting the fuel
speci?cally described.
What is claimed is:
1. A method of start fuel decay adjustment to a fuel
injector pulsewidth in an internal combustion engine
capable of using a ?exible fuel, said method comprising
the steps of:
saving a previous decayed start fuel injector pulse 55
width;
' calculating a run fuel injector pulsewidth;
determining if the decayed start fuel injector pulse
width is greater than the run fuel injector pulse
Width;
setting a fuel injector timer with the decayed start
fuel injector pulsewidth if the decayed start fuel
injector pulsewidth is greater than the run fuel
injector pulsewidth;
injector timer with the decayed start fuel injector pulse
width if the decayed start fuel injector pulsewidth is
greater than the run fuel injector pulsewidth or setting
the fuel injector timer with the run fuel injector pulse
width if the decayed start fuel injector pulsewidth is not
greater than the run fuel injector pulsewidth.
6. A method as set forth in claim 4 including the steps
of:
interpolating a decay rate of a fuel injector pulse
width in the fuel injector timer versus a coolant
temperature;
60
multiplying the decay rate by a number of cylinder
events since transferring from a start mode to a run
mode; and
subtracting the decay rate from the decayed start fuel
injector pulsewidth.
setting the fuel injector timer with the run fuel injec 65 7. A method as set forth in claim 2 wherein the step of
tor pulsewidth if the decayed start fuel injector
determining if the decayed start fuel injector pulsewidth
pulsewidth is not greater than the run fuel injector
is less than or equal to a predetermined value includes
pulsewidth;
the steps of:
13
5,415,145
the predetermined value; and
saving the decayed start fuel injector pulsewidth if
pulsewidth.
the decayed start fuel injector pulsewidth is not less 5
than or equal to the predetermined value.
8. A method of start fuel decay adjustment to a fuel
injector pulsewidth in an internal combustion engine
capable of using a ?exible fuel, said method comprising
10. A method as set forth in claim 8 including the
steps of:
I
interpolating a decay rate of a fuel injector pulse
width in the fuel injector timer versus a coolant
temperature;
multiplying the decay rate by a number of cylinder
the steps of:
determining if a decayed start fuel injector pulse
width is greater than a run fuel injector pulsewidth;
setting the fuel injector timer with the decayed start
fuel injector pulsewidth if the decayed start fuel
injector pulsewidth is greater than the run fuel
injector pulsewidth or setting the fuel injector
timer with the run fuel injector pulsewidth if the
decayed start fuel injector pulsewidth is not greater
than the run fuel injector pulsewidth; and
adjusting the ?exible fuel being sent to fuel injectors
14
calculating a run fuel injector pulsewidth prior to said
step of determining if the decayed start fuel injec
tor pulsewidth is greater than the run fuel injector
disabling the start fuel decay method if the decayed
start fuel injector pulsewidth is less than or equal to
events since transferring from a start mode to a run
mode; and
subtracting the decay rate from the decayed start fuel
injector pulsewidth.
15
. 11. A method as set forth in claim 8 including the step
of determining if the decayed start fuel injector pulse
width is less than or equal to a predetermined value
prior to said step of adjusting.
12. A method as set forth in claim 11 wherein the step
of determining if the decayed start fuel injector pulse
width is less than or equal to a predetermined value
of the internal combustion engine based on either
the decayed start fuel injector pulsewidth or the
run fuel injector pulsewidth.
25
9. A method as set forth in claim 8 including the steps
of:
saving a previous decayed start fuel injector pulse
width; and
includes the steps of:
disabling the start fuel decay method if the decayed
start fuel injector pulsewidth is less than or equal to
the predetermined value; and
the decayed start fuel injector pulsewidth is not less
than or equal to the predetermined value.
*
30
35
45
55
65
_
saving the decayed start fuel injector pulsewidth if
*
*
*
*