vauxhall corsa c

[radiosolutions]

1.2 petrol, 2003 reg, z12xe. problem is it has a misfire, fault codes stored p0300. p0302, cylinder 2 misfire, i have confirmed misfire on cylinder2 by disconnecting injector. which doesnt alter engine at all. moved injectors around,changed coilpack,sparkplugs, checked injector pulse with noid, compression test ,all fine and read the same. i puzzled now has anyone come across this before, thanks

[racin-snake]

sticking valves ?

[grimmer]

ecu?, quite common on vauxhalls to show missfire codes when ecu goes faulty

[radiosolutions]

thanks ,if it was ecu fault, would i lose injection pulse or spark, as its only on 1 cylinder

[racin-snake]

thanks ,if it was ecu fault, would i lose injection pulse or spark, as its only on 1 cylinder

yes it could manifest as one cylinder miss if not swithcing one coil earth or injector earth or v + power

can you scope the outputs ? of inj and check the wiring to ecu from both coil and injector on the failing cylinder ? remember 12v might show on a noid light but the wire to component might not be able to carry the current (due to a cracked wire or corrosion ) and not either snap the pintle of injector or in fact give a decent coil charge time so check the wiring and plug on ecu for firm connection and volt drop the wiring too

[smokey08]

I think a valve spring has broken, Seen it happen a few times.

[teuton]

You can "diagnose" this with old fashion vaccuum gauge, no big deal at all. basicaly a 4stroke engine is a mechanic device, don't forget it.
Otherwise scope the primary ignition circuit during WOT snap and you'll see if it is a fuel or ignition miss

[radiosolutions]

done a lot to this vehicle now, had head of engine,sent for recondition put back on still the same, what we found is happening is injector 2 cuts out after about 30 secs of being started. plug 2 is always wet with fuel, changed ecu, checked wiring from coil to ecu. just dont no what else to do now.

[teuton]

"injector 2 cuts out after 30 sec" means it won't get pulsed anymore? I guess so. As this happens with 2 ecus did you check wether the pulse is sent from the ecu and simply doesn't arrive at the component (injector2) or wether the ecu is not grounding the injector at all?
I can't imagine how the plug would be wet if the injector wasn't pulsing...
Supposed you loose injection pulse on #2,do you loose spark as well at the same time? If so, you may wanna scope the crank signal as there might be a problem with the sensor/reluctor
Otherwise if you do have spark and simply miss the injection pulse then you MUST have a wring issue or your 2nd ecu came with the same fault as the original which would be against the odds.

HTH

[MJRVR]

How do you know the injector 2 is cutting out?

Are you just disconnecting it and notice no difference in idle?

Surely if the plug is wet the injector is supplying fuel?

Sounds more like the cylinder is not firing for some reason other than lack of fuel.

Martin

done a lot to this vehicle now, had head of engine,sent for recondition put back on still the same, what we found is happening is injector 2 cuts out after about 30 secs of being started. plug 2 is always wet with fuel, changed ecu, checked wiring from coil to ecu. just dont no what else to do now.

[Liteace]

As Teuton said the only way you are going to solve this is by scoping injector 2 (or scope them all) and primary \ secondary ignition to see whats going on, you can set your scope to 5 or 10 secs per division or even faster, then set the trigger and you should see where and why the problem occurs

[radiosolutions]

all sorted now finally, thanks for all info, superb. it turned out to be the head, it was not recon right, put another head on all fine. the injector was cutting out as the ecu recognised misfire on 2 , it stops the injector as a safety issue so the bore doesnt fill up of unburnt fuel. super info everyone. thanks