Functional Operation; Fuel Control; On-Board Diagnostics - Chrysler Sebring 2005 Service Manual

GEN ERAL I N FORM AT I ON

3.2 FUNCTIONAL OPERATION

3.2.1 FUEL CONTROL

Th e P CM con t r ols t h e a ir /fu el r a t io of t h e en gin e
by va r yin g fu el in ject or on t im e. E n gin e loa d is
ca lcu la t ed u sin g t h e speed den sit y m et h od u sin g
en ign e speed, m a n ifold a bsolu t e pr essu r e, a n d a ir
t em per a t u r e ch a n ge.
Differ en t fu el ca lcu la t ion st r a t egies a r e u sed de-
pen din g on t h e oper a t ion a l st a t e of t h e en gin e.
Du r in g cr a n k m ode, a lon ger pu lse widt h fu el pu lse
is deliver ed followed by fu el pu lses det er m in ed by a
cr a n k t im e st r a t egy. Cold en gin e oper a t ion is det er-
m in ed via a n open loop st r a t egy u n t il t h e O2
sen sor s h a ve r ea ch ed oper a t in g t em per a t u r e. At
t h is poin t , t h e st r a t egy en t er s a closed loop m ode
wh er e fu el r equ ir em en t s a r e ba sed u pon t h e st a t e of
t h e O2 sen sor s, en gin e speed, MAP, t h r ot t le posi-
t ion , a ir t em per a t u r e, ba t t er y volt a ge, a n d coola n t
t em per a t u r e.

3.2.2 ON-BOARD DIAGNOSTICS

Th e P CM h a s been pr ogr a m m ed t o m on it or m a n y
differ en t cir cu it s of t h e fu el in ject ion syst em . Th is
m on it or in g is ca lled on -boa r d dia gn osis.
Cer t a in cr it er ia , or a r m in g con dit ion s, m u st be
m et for a t r ou ble code t o be en t er ed in t o t h e P CM
m em or y. Th e cr it er ia m a y be a r a n ge of: en gin e r pm ,
en gin e t em per a t u r e, a n d/or in pu t volt a ge t o t h e
P CM. If a pr oblem is sen sed wit h a m on it or ed
cir cu it , a n d a ll of t h e cr it er ia or a r m in g con dit ion s
a r e m et , t h en a t r ou ble code will be st or ed in t h e
P CM.
It is possible t h a t a t r ou ble code for a m on it or ed
cir cu it m a y n ot be en t er ed in t o t h e P CM m em or y
even t h ou gh a m a lfu n ct ion h a s occu r r ed. Th is m a y
h a ppen beca u se on e of t h e t r ou ble code cr it er ia h a s
n ot been m et .
Th e P CM com pa r es in pu t sign a l volt a ges fr om
ea ch in pu t device wit h specifica t ion s (t h e est a b-
lish ed h igh a n d low lim it s of t h e r a n ge) t h a t a r e
pr ogr a m m ed in t o it for t h a t device. If t h e in pu t
volt a ge is n ot wit h in specifica t ion s a n d t h e ot h er
t r ou ble code cr it er ia h a s been m et , a t r ou ble code
will be st or ed in t h e P CM m em or y.
Th e On Boa r d Dia gn ost ics h a ve evolved t o t h e
secon d Gen er a t ion of Dia gn ost ics r efer r ed t o a s
OBDII/E u r o St a ge III OBD. Th ese OBDII/E u r o
St a ge III OBD Dia gn ost ics con t r ol t h e fu n ct ion s
n ecessa r y t o m eet t h e r equ ir em en t s of Ca lifor n ia
OBDII, F eder a l OBD r egu la t ion s a n d E u r opea n
r egu la t ion s. Th ese r equ ir em en t s specify t h e in clu -
sion of a Ma lfu n ct ion In dica t or Ligh t (MIL) loca t ed
on t h e in st r u m en t pa n el. Th e pu r pose of t h e MIL is
t o in for m t h e veh icle oper a t or in t h e even t of a
m a lfu n ct ion of a n y em ission syst em or com pon en t .
MIL La m p S tra te g y
I/M Rea din ess OK t o t est = Ke y On En g in e OF F
– MIL La m p will r em a in on u n t il t h e veh icle is
st a r t ed or Ign it ion is t u r n ed off.
I/M n ot r ea dy for t est in g = Ke y On En g in e OF F
– MIL La m p on solid for (15) secon ds t h en MIL
La m p will fla sh on /off for (5) secon ds t h en it will
r em a in on u n t il t h e veh icle is st a r t ed or t h e Ign it ion
is t u r n ed off.
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