Runs Rough On Deceleration/Backfire - Mazda 121 Workshop Manual

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
N o
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 - 1 1 9
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