Suzuki WagonR+ RB310 Service Manual page 2429

6-70 ENGINE DIAGNOSIS
DTC P0300 RANDOM MISFIRE DETECTED (Misfire detected at 2 or more
cylinders)
DTC P0301 CYLINDER 1 MISFIRE DETECTED
DTC P0302 CYLINDER 2 MISFIRE DETECTED
DTC P0303 CYLINDER 3 MISFIRE DETECTED
DTC P0304 CYLINDER 4 MISFIRE DETECTED
Ignition switch
Relay box
Main
fuse
CIRCUIT DESCRIPTION
ECM monitors crankshaft revolution speed and engine speed via the crankshaft position sensor and cylinder No.
via the camshaft position sensor. Then it calculates the change in the crankshaft revolution speed and from how
many times such change occurred in every 200 or 1000 engine revolutions, it detects occurrence of misfire.
When ECM detects a misfire (misfire rate per 200 revolutions) which can cause overheat and damage to the three
way catalytic converter, it makes the malfunction indicator lamp (MIL) flash as long as misfire occurs at that rate.
After that, however, when the misfire rate drops, MIL remains ON until it has been judged as normal 3 times under
the same driving conditions.
Also, when ECM detects a misfire (misfire rate per 1000 revolutions) which will not cause damage to three way
catalytic converter but can cause exhaust emission to be deteriorated, it makes MIL light according to the 2 driving
cycle detection logic.
Ignition coil assembly
for No.1 & No.4 spark plugs
Fuse box
Main relay
To ignition switch
Ignition coil assembly
for No.2 & No.3 spark plugs
No.1 injector
No.2 injector
No.3 injector
No.4 injector
CMP sensor
CKP sensor