CYL # 2 MISFIRE

[mekanika]

Hi All,My K12 1.0 engine has cyl #2 misfire fault. Removed cyl-head and found cyl #2 valves are leaking. My question is how does ECU/ECM engine control unit/module picked-up misfire fault from cyl #2 which is mechanical fault and how/why there is no spark on cyl #2? Thanks.

 

[frank]

i think the ecu can only flag a defective coil, you would need a knock sensor for each cylinder otherwise eh

 

[mekanika]

i think the ecu can only flag a defective coil, you would need a knock sensor for each cylinder otherwise eh

All fuel injectors,coils & spark plugs are O.K,.....i have swapped them from other cylinders to cyl #2 and they did not work....they work fine on other cylinders but not cyl #2......valves leaking,mechanical fault and not electrical fault. How does ECU/ECM pick-up the misfire?

 

[frank]

All fuel injectors,coils & spark plugs are O.K,.....i have swapped them from other cylinders to cyl #2 and they did not work....they work fine on other cylinders but not cyl #2......valves leaking,mechanical fault and not electrical fault. How does ECU/ECM pick-up the misfire?

i think the ecu can only flag a defective coil, you would need a knock sensor for each cylinder otherwise eh

the 3rd wire on each coil is for feedback, so without 4 knock sensors or 4 lambda,s i cant see how the ecu can flag a mechanical missfire

 

[mekanika]

o.k,how does the coil feedback wire pick-up a misfire....that is mechanical,.......insufficient compression/valves leaking!!

 

[frank]

o.k,how does the coil feedback wire pick-up a misfire....that is mechanical,.......insufficient compression/valves leaking!!

the 3rd wire senses the induction from the windings in the coil i guess ? so it can tell if a spark was generated
did you do a compression test ? any pic of the valves and seats ?

 

[plmval]

All fuel injectors,coils & spark plugs are O.K,.....i have swapped them from other cylinders to cyl #2 and they did not work....they work fine on other cylinders but not cyl #2......valves leaking,mechanical fault and not electrical fault. How does ECU/ECM pick-up the misfire?

Misfire monitoring by ECU

ECU constantly monitors instantaneous engine RPM acceleration due to each cylinder as it fires. Cylinder RPM acceleration below average of the cylinders or below program parameters, red flags a misfire for that cylinder.

May I suggest you check the number two ignition coil power supply and wiring continuity all the way back to the switching source?

 

[frank]

Misfire monitoring by ECU

ECU constantly monitors instantaneous engine RPM acceleration due to each cylinder as it fires. Cylinder RPM acceleration below average of the cylinders or below program parameters, red flags a misfire for that cylinder.

May I suggest you check the number two ignition coil power supply and wiring continuity all the way back to the switching source?

on a random or multiple misfire yes, but how can it detect a specific cyl#2 misfire ?

 

[plmval]

on a random or multiple misfire yes, but how can it detect a specific cyl#2 misfire ?

By OBD11 control system comparing acceleration due to each cylinder at the moment of ignition.

Reference; http://www.underhoodservice.com/tech-feature-detecting-misfires-in-obd-ii-engines/