Hi, I am currently looking at a Corsa C 1.2 Twin port. The vehicle starts and runs fine for about 20 seconds then the eng man light starts to flash and the engine misfires.
Fault codes stored are P0300 Random / Multiple misfire, P0301 Misfire Cylinder 1 and P0304 Misfire Cylinder 4. Switch the ignition off, restart the vehicle and it runs fine again for about 20 seconds then the fault reoccurs.
On my initial look, I attached a vacuum gauge to the inlet manifold which displayed good vacuum with a steady needle so the engine mechanically seems good.
I decided to look at the ignition primary voltage and current and injector voltage and current, it was obvious that their was no command form the ECU or current for injectors 1 + 4, then I remembered that the ECU can turn these off when a misfire is detected . Ignition off then restart the engine all 4 injector command and current are visible, engine seems to run fine, no misfire that I can notice then injectors 1 + 4 are turned off and a misfire is obvious. It looks like the ECU is detecting a misfire then turning off the injectors for the relevant cylinders.
On returning to the vehicle the following day looking again at ignition primary their were 2 and sometimes 3 saturation events for each cycle. This looked very odd to me, zooming in on the first event I noticed a very brief high spark line voltage, I removed the plugs, they were worn out so I replaced them and the spark line voltage lowered but still had more that one saturation period. After quite a while this did return back to one event.
I am wondering if the captures show a fault to a more experienced eye, if anyone can explain what is happening in the captures and may be suggest some further tests to try get to the bottom of this fault. I was considering looking at fuel quality next before doing too much more, thank you for your time, kind regards, Andy
(Looks like some of my files are too big to upload)
- 05 corsa misfire. crank sensor.psdata
- Coil current ramps and crank sensor, more than 1 coil saturation period
- (515.85 KiB) Downloaded 245 times
- 05 corsa misfire inj current.psdata
- Ignition primary and injector before and afetr fault, normal coil saturation
- (7.38 MiB) Downloaded 209 times
- 05 corsa misfire..psdata
- Ignition Primary and Coil current, 1 and 2 coil saturation events
- (4.35 MiB) Downloaded 217 times