Vr6 missfire - cylinder 3 not firing - lost a cylinder

[edd 0]

Hi All

 

Need to delve into the knowledge bank for some reassurance please :)

 

I lost a cylinder on the way up the M5 a few days ago, it was late and my RAC had run out so had to carry on and do the remaining 30 miles home

 

I have done some diagnostics this morning and it seems to be cylinder 3 that is not firing (middle top as you look into the engine bay from the front of the car). The spark Plug is wet upon removal. I pulled the plugs off the coilpack one by one and all but one have spark (as my right hand will currently vouch) It is the bottom right coilpack output as you look at the coilpack which has NO spark (which also correlates to cylinder 3) Ive swapped HT leads over etc and the fault remains as i would expect

 

I ordered a new BERU coilpack yesterday (and new HT and sparkplugs etc) as im feeling guilty that she has been neglected but it is a few days until they arrive

 

My Questions are

 

1) I thought the coilpacks always lost two banks of cylinders when they fail. Can they just fail on one. Could the problem therefore be elsewhere i.e. ignition control module or something else

 

2) Will there be any resulting issues from running the car up the motorway after i lost a cylinder. assume unburnt fuel will have got to the lambda etc could this cause any issues?

 

Many thanks for any response

 

Edd

[edd 0]

Edit: I meant I thought the coil pack always lost 2 cylinders if they failed (not 2 banks as stated)

[dr_mat 0]

They do lose two cylinders. There are three coils in the CP. That implies your coil pack has a failed link between that coil and the output. Or, and I've never ever heard of this before, there is an issue with the output from your ECU. But equally there are only three output lines from the ECU so if one cylinder works the other will get fired too.

[Kevin Bacon 5]

You only lose 2 cylinders when the low tension side fails, I.e. a broken wire or failed ignition driver inside the ECU.

[edd 0]

So if I've only lost one cylinder and Correspondingly only lost spark from one coilpack outlet is it most likely to be the coilpack or ecu at fault. It was weird how it went mid drive having covered about 100 miles already that day.

[Kevin Bacon 5]

It'll be the black plastic/resin section of the coilpack that's at fault. Although it's a wasted spark system, it still consists of 6 individual coils and it's not often that 2 go at the same time. Yeah that's the nature of electrical problems, the components either work or they don't, so can shutdown without warning!

 

I suppose you could confirm by swapping the partner cylinder's dry plug into cyl 3 and swap the lead over on the coilpack. If it then fires, it's defo the coilpack, but as you've bought replacement bits already, you may as well slap it all on and call it job done - hopefully!

[edd 0]

new coilpack sorted it

 

went for a BERU in the end due to a price and availability that suited me, the old coilpack was also Beru and looks at though it was from 2009.

 

before rhis is closed down were my concerns regarding running on 5 cylinders for 30 miles up the motorway and the associated unburnt fuel and potential for lambda probe damage way off the mark or could this be an issue?

 

edd

[dr_mat 0]

It could, potentially, cause issues with the cat, but there's nothing you can do about it now.

Just drive it and wait for the MOT to find out ...

[edd 0]

New coilpack sorted all. Running beautifully actually