Dodge 2006 Sprinter, Manual

Page: 1713 / 2315

posit ion a ga in st t h e open in g for ces a pplied t o it s
pr essu r e st a ge (F ig. 11).
Injector opens (start of injection)
Th e solen oid va lve is en er gized wit h t h e picku p
cu r r en t wh ich ser ves t o en su r e t h a t it open qu ickly.
Th e for ce exer t ed by t h e t r igger ed solen oid n ow
exceeds t h a t of t h e va lve spr in g a n d t h e a r m a t u r e
open s t h e bleed or ifice. Alm ost im m edia t ely, t h e h igh -
level pick-u p cu r r en t is r edu ced t o t h e lower h oldin g
cu r r en t r equ ir ed for t h e elect r om a gn et . Th is is possi-
ble du e t o t h e m a gn et ic cir cu it ’s a ir ga p n ow bein g
sm a ller. Wh en t h e bleed or ifice open s, fu el ca n flow
fr om t h e va lve con t r ol ch a m ber in t o t h e ca vit y sit u -
a t ed a bove it , a n d fr om t h er e via t h e fu el r et u r n t o
t h e t a n k. Th e bleed or ifice pr even t s com plet e pr es-
su r e ba la n ce, a n d t h e pr essu r e in t h e va lve con t r ol
ch a m ber sin ks a s a r esu lt . Th is lea ds t o t h e pr essu r e
in t h e va lve-con t r ol ch a m ber bein g lower t h a n t h a t in
t h e n ozzle’s ch a m ber volu m e wh ich is st ill a t t h e
sa m e pr essu r e level a s t h e r a il. Th e r edu ced pr essu r e
in t h e va lve-con t r ol ch a m ber ca u ses a r edu ct ion in
t h e for ce exer t ed on t h e con t r ol plu n ger, t h e n ozzle
n eedle open a s a r esu lt , a n d in ject ion st a r t s (F ig. 11).
Injector opens fully
Th e con t r ol plu n ger r ea ch es it s u pper st op wh er e it
r em a in s su ppor t ed by a cu sh ion of fu el wh ich is gen -
er a t ed by t h e flow of fu el bet ween t h e bleed a n d feed
or ifices. Th e in ject or n ozzle h a s n ow open ed fu lly,
a n d t h e fu el is in ject ed in t o t h e com bu st ion ch a m ber
a t a pr essu r e a lm ost equ a l t o t h a t in t h e fu el r a il
(F ig. 11).
Injector closes (end of injection)
As soon a s t h e solen oid va lve is n o lon ger t r ig-
ger ed, t h e va lve spr in g for ces t h e a r m a t u r e down -
wa r ds a n d t h e ba ll closes t h e bleed or ifice. Th e
a r m a t u r e is a 2–piece design . H er e, a lt h ou gh t h e
a r m a t u r e pla t e is gu ided by a dr iver sh ou lder in it s
down wa r d m ovem en t , it ca n “over spr in g” wit h t h e
r et u r n spr in g so t h a t it exer t s n o down wa r ds-a ct in g
for ces on t h e a r m a t u r e a n d t h e ba ll. Th e closin g of
t h e bleed or ifice lea d t o pr essu r e bu ild u p in t h e con -
t r ol ch a m ber via t h e in pu t fr om t h e feed or ifice. Th is
pr essu r e is t h e sa m e a s t h a t in t h e r a il a n d exer t s a n
in cr ea sed for ce on t h e con t r ol plu n ger t h r ou gh it s
en d fa ce. Th is for ce, t oget h er wit h t h a t of t h e spr in g,
n ow exceeds t h e for ce exer t ed by t h e ch a m ber volu m e
a n d t h e n ozzle n eedle closes. In ject ion cea ses a s soon
a s t h e n ozzle n eedle com es u p a ga in st it s bot t om st op
a ga in (F ig. 11).
STAN DARD PROCEDU RE
STANDARD PROCEDURE - INJECTOR CLASSI-
FICATION
NOTE: Fuel Injectors have different flow rates.
When ALL injectors are removed, re-enter all injec-
tor six digit codes.
Th e cla ssifica t ion of in ject or s in t o 3 cla sses
descr ibes t h e qu a n t it y ch a r a ct er ist ic of t h e in ject or.
Th is will m a ke it possible in t h e fu t u r e t o m a t ch t h e
en gin e soft wa r e t o t h e t oler a n ces of t h e in ject or
wit h in a m or e n a r r owly gr a du a t ed r a n ge. Cla ssifica -
t ion ca n be clea r ly r ecogn ized, a n d a ssign ed on ly by
m ea n s of a DRBIII
! .
Cla ssified in ject or s ca n be r ecogn ized by t h e six-
digit a lph a n u m er ic code or pa r t n u m ber a n d iden t ifi-
ca t ion on t h e m a gn et ic h ea d (cir cle wit h a n u m ber
bet ween 1 a n d 3 in side) (F ig. 12). Th e n u m ber cor r e-
spon ds t o t h e cla ssifica t ion st a ge.
Th ese gen er a l con dit ion s equ a lly a pply if, a s a
r esu lt of r epla cin g a n en gin e, ca r r yin g ou t r epa ir s t o
t h e cylin der h ea d et c., t h e cylin der select ive a ssign -
m en t of t h e in ject or s or t h e en gin e con t r ol m odu le
a ssign m en t m a y h a ve ch a n ged. If pr oper a t t en t ion is
n ot pa id t o t h e cla ssifica t ion on t h ese veh icles dr ive-
a bilit y a n d sm okin g con cer n s cou ld r esu lt .
If a n in ject or is r epla ced, it is t h en n ecessa r y t o
a ssign t h e cla ssifica t ion n u m ber t o t h e cor r espon din g
cylin der wit h t h e
D RB III ! in t h e con t r ol m odu le.
Fig. 12 INJECTOR CLASSIFICATION MARKINGS
1 - ELECTRICAL CONNECTOR
2 - SIX-DIGIT ALPHANUMERIC CODE
VA FUEL INJECTION 14 - 37