Omega Owners Forum
Omega Help Area => Omega General Help => Topic started by: Alex W on 18 July 2011, 19:30:16
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I need some help in the best procedure to further diagnose my misfiring V6.
I don't know if its the plugs, leads or Dis/Coil pack.
I have not been able to remove the coil pack but a limited torchlight inspection did not reveal any splitting like that shown in the maintenance guide photos.
I can't afford to just go replacing parts at random until I stumble upon the solution (I've already replaced the crank sensor, the breathers have been cleaned and a split breather pipe resolved).
Fault codes (19 & 21)have not cleared despite 20+ starts.
Can anyone give me some guidance as to the best way to proceed.?
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have you lifted the plug leads from the plugs to check if there is any oil in the plug recesses?
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Cam cover gaskets are OK
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19 is crank sensor...it can cause misfiring when failing...if you have a code 19 you almost certainly have a failing crankshaft sensor...
Is the other code definitely 21?? Or 12 i.e. Start of sequence??
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Take the crank sensor back, tell them it is apparently faulty and you want another one. If its still showing 19 then imo the new sensor is a dud.Wont be the first time its happened. :y
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The Code 21 was caused by my failure to plug in the electrical connector to the throttle housing when I put the plenum back on ( I replaced the HBV as well). That was over 20 starts ago.
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OK, we need to clear the codes manually, and see what comes back. I was desperately trying to save you the journey...
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Thanks Jaime, when would be convenient?
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I now suspect that as my fault codes still refuse to clear, despite many more than 20 starts, the code 19 that caused me to just replace my crank sensor may well have been the same fault code, still in the car from last year, from when the crank sensor really failed.
I have read some other forum posts about misfires and it seems that a misfiring engine would not necessarily generate an engine fault code at all, at least not in a car as old as mine (2000 W).
Can anyone confirm that?
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Correct - misfires on the older engines are not detected, so HT issues often result in misfires, which will not flag codes.
Does it hunt at idle?
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I was getting 19 when I had a misfire , totally baffled me and resulted in a barny at the factors over the pattern c/sensor and the purchase of a completely unnescessary new sensor from Vaux, culprit turned out to be the DIS which looked perfect when removed.
I think the pattern DIS work ok unlike the pattern crank sensors.
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Correct - misfires on the older engines are not detected, so HT issues often result in misfires, which will not flag codes.
Does it hunt at idle?
I'm not sure what "hunt at idle" means, but the revs are not steady at idle, constantly going up and down, you can feel the car vibrate from the driver seat. Sometimes the revs drop down and you think its going to stop but then it picks up again.
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Correct - misfires on the older engines are not detected, so HT issues often result in misfires, which will not flag codes.
Does it hunt at idle?
I'm not sure what "hunt at idle" means, but the revs are not steady at idle, constantly going up and down, you can feel the car vibrate from the driver seat. Sometimes the revs drop down and you think its going to stop but then it picks up again.
Have you checked for vac leaks :question
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Correct - misfires on the older engines are not detected, so HT issues often result in misfires, which will not flag codes.
Does it hunt at idle?
I'm not sure what "hunt at idle" means, but the revs are not steady at idle, constantly going up and down, you can feel the car vibrate from the driver seat. Sometimes the revs drop down and you think its going to stop but then it picks up again.
Have you checked for vac leaks :question
Yep, fixed a split plenum breather pipe, no change. Changed the spark plugs today (they were due anyway) no change.
Looks like it must be the DIS Pack or plug leads.
Is there any way of determining which it is without costly trial and error? I haven't had the dis pack out because of accessibility but a torchlight inspection revealed no obvious splits like in the guide photos.
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You can try getting hold of some known good leads and swapping them in pairs( two longest ones are easiest to do this with) but if the Dis is goosed it will be affecting prob 2 cylinders. If your delving deep you may as well change the DIS, you really dont want to be going in there twice :o
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If I had the cash I'd just swap the lot out and be done with it, but times are hard and the credit card is already groaning under the weight of my debts.
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You can try pulling one lead at a time and see whether there`s a change in engine idle. Crude way to test the dis is to unplug knock sensor and start the engine, because of the higher voltage then required to start the car it will have a very pronounced misfire, but if the dis is faulty this option could kill it totally
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You can try pulling one lead at a time and see whether there`s a change in engine idle. Crude way to test the dis is to unplug knock sensor and start the engine, because of the higher voltage then required to start the car it will have a very pronounced misfire, but if the dis is faulty this option could kill it totally
I had hoped that changing the spark plugs might give me a clue about where my misfire was and how many cylinders were affected but sadly I could see no real difference between them as I took them out.
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You can try pulling one lead at a time and see whether there`s a change in engine idle. Crude way to test the dis is to unplug knock sensor and start the engine, because of the higher voltage then required to start the car it will have a very pronounced misfire, but if the dis is faulty this option could kill it totally
I had hoped that changing the spark plugs might give me a clue about where my misfire was and how many cylinders were affected but sadly I could see no real difference between them as I took them out.
Won`t make one iota of difference if any of the leads are donald. As suggested, try pulling one lead at a time
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You can try pulling one lead at a time and see whether there`s a change in engine idle. Crude way to test the dis is to unplug knock sensor and start the engine, because of the higher voltage then required to start the car it will have a very pronounced misfire, but if the dis is faulty this option could kill it totally
I had hoped that changing the spark plugs might give me a clue about where my misfire was and how many cylinders were affected but sadly I could see no real difference between them as I took them out.
Won`t make one iota of difference if any of the leads are donald. As suggested, try pulling one lead at a time
I had hoped that the spark plug/s from the non-firing cyclinder/s might reveal the culprit/s.
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You can try pulling one lead at a time and see whether there`s a change in engine idle. Crude way to test the dis is to unplug knock sensor and start the engine, because of the higher voltage then required to start the car it will have a very pronounced misfire, but if the dis is faulty this option could kill it totally
I had hoped that changing the spark plugs might give me a clue about where my misfire was and how many cylinders were affected but sadly I could see no real difference between them as I took them out.
Won`t make one iota of difference if any of the leads are donald. As suggested, try pulling one lead at a time
I had hoped that the spark plug/s from the non-firing cyclinder/s might reveal the culprit/s.
Not if the misfire has been only recent
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If its hunting at idle, sounds like it is, are there any air leaks?
Does it misfire when cruising at motorway speeds? Does it accelerate as expected?
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I,ve had a similar prob.(post /rotten egg smell).
First started to change plug leads and No 4 broke away from plug holder ,it had been failing for sometime as the core was burnt away although outer looked okay.Anyway while i was in there I changed the dis pack and hbv and new plugs /leads.
I did that as I think I have left plenty of skin and blood in there as didn't want take apart again (who needs smart water).Any way mis has gone ,definate plug lead U/S ,dis pack maybe okay,hbv just incase.next check cats and fit new Exh.
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If its hunting at idle, sounds like it is, are there any air leaks?
Does it misfire when cruising at motorway speeds? Does it accelerate as expected?
It misfires at all speeds, especially bad around 50 mph, less noticeable above and below that. Poor acceleration.
As a mentioned on another thread ("running on 5 a day")on changing the spark plugs I noted that the front passenger side plug well had previously at some time had a couple of inches of water in it. The top of the spark plug was very rusty and the bottom couple of inches of the plug lead were covered in rust residue. No actual water was present but I now suspect that the plug lead has been damaged by this water ingress and hence my misfire.
There is no obvious sign of how the water got in there but it is near to the thermostat and a coolant pipe runs along the plenum edge above the cam cover gasket.
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No2 plug :o, thats an unusual one to see wet. Only possible way in is from above.
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No2 plug :o, thats an unusual one to see wet. Only possible way in is from above.
Front cylinder on passenger side needs Spark lead No 2?
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Correct - misfires on the older engines are not detected, so HT issues often result in misfires, which will not flag codes.
Does it hunt at idle?
I'm not sure what "hunt at idle" means, but the revs are not steady at idle, constantly going up and down, you can feel the car vibrate from the driver seat. Sometimes the revs drop down and you think its going to stop but then it picks up again.
Have you checked for vac leaks :question
I fixed a split plenum breather pipe but can't see any obvious vac leaks. Is there a way of checking for such leaks apart from listening for a hissing sound?
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Went to change spark lead No.2 today then lead 6 just fell off the diff pack revealing corroded terminal and lead end.
I decided I must get the dis pack out for a proper inspection and after an epic struggle I have found the culprit. The Dis Pack is split just like in the photos on the maintenance guide.
Hopefully replacing this and lead 6 will finally solve my misfire problem.
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I just wanted to add 'Thank You' to everyone that contributed to helping me sort this out.
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Sounds like you have found the problem :y
I'm still concerned about that 19, see what happens a week or so after the DIS is fixed, and let us know :y
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Sounds like you have found the problem :y
I'm still concerned about that 19, see what happens a week or so after the DIS is fixed, and let us know :y
Will do, thanks.
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Final update, replaced the Dis pack and a corroded plug lead today.
Misfire cured, everything back to normal now. Thanks again to everyone that helped.
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Good new AlexW.
In a week or so, see if that 19 has disappeared :y