Mazda 121 - Runs Rough on Deceleration;Backfire

TFOUBLESHOOTING GUIDE F
21
RUIIS BOUGH ON DECELERATION/BAC|(FIRE
DESCfitP.
noN
.Engine
lirns rough w+)ile dec€lerating and abnormal combustion occurc in exhausl system
.Transaxle
in normai condit on
rrRoualEsHooTr
c HtNTsl
O
Ar/Fue{ mxlure
too rich
.Arr
cleaner element
clogged
.Fuel
inieclion
cortro malJunclion
(Fuel
cut control)
.Iniector
fuel leakage
.Throttle
sensor malf
unction
.
Dashpol malfunciion
t]tsPEcTtol{ ACTION
1 ls OO" display€d on SellDiagnosas Checker
with ignitlon swilch ON?
u
p'g'e
F-6'7
IEST SW: SEIF TEST
Go to next step
No llallunctlon Codo No, dasplayed
Check
lor
cause Geter to soeciiied
check sequence)
rt
page
F-70
"88"
tla3he€
Check ECU teminal 1F voltage
cz
page
F-114
Volt.ge: Approx. 12V
(lgnition
swilch
Ol{)
+
lf
OK,
replace
ECU
cz
psge
F-112
4
ll nol
OK, check
wiring beiween
ECU and Self-Diagnos,s
Chsckar
2
ls
there air eal.age at inlake
air system com
3
ls
air cleaner
element
clean?
F
page
F-62
Go lo nexI step
No
Aeplace air cleaner
element
Are ECU terminal voliages
OK?
(Especially
21v1 and
20)
.:7
page
F-112
Ch€ck lof calse .7
page
F-1t5
F-117
F-119
5 ls lhere 0V al ECU
2V leminal above 3,000 rpm
(Engine
signal
monilor
green
lamp illuminates)
Try known
good
ECU and check ii
6 ls lhrotle sensor OK?
Ei
pag6
F-122
Adjusl
(r
page
F-1ZI
F-53