Hey,

My S has been suffering from a slight misfire for the past month or so. I have done all the usual things, map whack, cleaned TB, IACV etc etc but it still happens on occasion. It is only ever when the car starts, doesn't matter if it is from hot or cold. It idles a little rough and you can clearly hear a misfire, but after sitting for about 15-20 seconds it smooths out and sounds perfectly normal. It drives perfectly once going too and I have no warning lights on the dash.

Any ideas?

Someone suggested coil pack to me? I am not really sure what I am checking for there or how to test them? I took these photos earlier, the only very slight difference I see on one is a little gunk where there is a white seal on the others, could this be an issue?




Any help appreciated.

Thanks

 

With a problen that intermittant there is only one sure way to tell, beg or borrow a spare pack from someone and try it one cylinder at a time if it fixes it on one cylinder then thats your villan, if not then its not a coilpack. Tappet adjustment is a possibility as things will change as the engine warms up.

 

Hmmm ok, suppose it should maybe be plugged in to check for fault codes or something. The tappets were all done about 6 months ago, so I would hope they are ok?

Is there any way to test a coil pack one by one for example to see if one is faulty?

Thanks

 

I dripped some oil down my #4 coil once, and that caused a misfire. Wiped it off and it was fine. Is the gunk oil?

But I also had two fail, and they didn't look any different from normal, so I'm not sure you can tell. Presumably if it fails completely you can tell with a multimeter, but whilst it's intermittent you can only change things and hope.

I can tell you that I'm at least 60% sure my misfires at idle were caused by an injector, and the coil caused misfires were generally under load in the mid range.

 

 

Thats what I posted. You will need a spare pack.

 

That oil is negligible really, wouldn't cause a misfire like you're describing.

The rocker gasket failed on my old Astra coupe turbo without me knowing... 4" deep in oil! and that never misfired!

 

I always thought coil packs contained "oil" to help dissipate the heat - is it possible that the gunk on the end of that coil pack has come from the coil pack itself ?

I'd scan for fault codes, check which cylinder has the misfire, swap coil packs with a different cylinder then try again. If the misfire moves/doesn't move then that will help you track down the culprit.

Found a nice checklist here that might help you out.

 

You can't always trust the codes some have found they indecate the wrong clninder but it will give some idea.

 

Same has just happened to me! My plugs need replacing and I need a cool pack, had to limp to Honda from work and it can't be done till Monday!