Should my EML worry me?

Should my EML worry me?

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Nads02

Original Poster:

120 posts

37 months

Monday 19th April 2021
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So I knew I had a leaking rocker cover gasket since new year. Have noticed a occasional slight misfire when idling but since then it's got worse. I drive about 300 miles a week in my 2004 yaris 1.0 and today my engine was shaking really badly, at all speeds. At 2nd gear doing 15mph throttle flat to the floor doesn't pick up speed for a couple of seconds. Engine light turned on. Not driving (or working) until I get the spark plugs changed with the gasket asap. But could I drive it 1 mile with a really bad misfire? My mechanic is about 1 mile up the road but I'm not too sure about driving it there?

E-bmw

9,105 posts

151 months

Tuesday 20th April 2021
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You SHOULD be OK for 1 mile but with unburnt fuel going into the cat due to your misfire there is always a possibility it could go wrong.

You should also prepare yourself for more of a bill than a gasket & a set of plugs.

Nads02

Original Poster:

120 posts

37 months

Tuesday 20th April 2021
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Mechanic changed the plugs and said they were dripping with oil. Said it'll happen again if I don't change the rocker cover gasket so my cars booked in for Thursday morning. Eml was p0302 I think, cylinder 2 misfire. But it has gone away, hopefully for good.

E-bmw

9,105 posts

151 months

Wednesday 21st April 2021
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Oil in the spark plug well in itself shouldn't cause a misfire.

The HT connection to the plug is normally behind a seal & oil is an isolator rather than conductor of electricity.

aka_kerrly

12,416 posts

209 months

Wednesday 21st April 2021
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E-bmw said:
Oil in the spark plug well in itself shouldn't cause a misfire.

The HT connection to the plug is normally behind a seal & oil is an isolator rather than conductor of electricity.
You seem to contradict yourself there.

Oil in the spark plug chambers and a HT lead/coil pack swimming in oil will NOT help the ignition system at all and will cause a misfire.

Probably a two piece rocker cover with an outer seal and a inner seal that will both need replacing.

Pastie Bloater

694 posts

162 months

Wednesday 21st April 2021
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Nads02 said:
Mechanic changed the plugs and said they were dripping with oil. Said it'll happen again if I don't change the rocker cover gasket so my cars booked in for Thursday morning. Eml was p0302 I think, cylinder 2 misfire. But it has gone away, hopefully for good.
Hopefully but chances are your coil pack(s) are already nackered from having the spark plug to coil connections submerged in oil (this damages the coils, not plugs). Removing the oil helps but longer term you might find it starts misfiring again, at that point change the coils and you should be ok.

I had this on a V8 where after changing gaskets and cleaning out the oil basically week by week a coil pack failed until week 4 where I changed the lot and it was fine after that.

E-bmw

9,105 posts

151 months

Wednesday 21st April 2021
quotequote all
aka_kerrly said:
E-bmw said:
Oil in the spark plug well in itself shouldn't cause a misfire.

The HT connection to the plug is normally behind a seal & oil is an isolator rather than conductor of electricity.
You seem to contradict yourself there.
Not at all.

The connection end of most coil packs is at the top of a closed cylinder, so (like an upturned glass when submerged in water) air pressure will tend to keep the oil out & as the connection to the plug itself is a positive spring loaded connection, even if the oil did get up past the seal it can't get between the plug & coil.

On top of that, I did say "shouldn't" as there may be coil packs I have yet to come across that aren't closed & don't have spring loaded connections.

Nads02

Original Poster:

120 posts

37 months

Thursday 22nd April 2021
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Got the rocker cover changed and my car is running super smooth. Sometimes it feels as though the engine isn't even on then I see the revs at 800! I got a set of 4 coil packs, from another yaris I scrapped. Had a look at the camshaft and timing chain, looks like it's new! Chain is tight and camshaft looks good

Pastie Bloater

694 posts

162 months

Thursday 22nd April 2021
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Nads02 said:
Got the rocker cover changed and my car is running super smooth. Sometimes it feels as though the engine isn't even on then I see the revs at 800! I got a set of 4 coil packs, from another yaris I scrapped. Had a look at the camshaft and timing chain, looks like it's new! Chain is tight and camshaft looks good
Happy days, cheapest misfire fix I ever had was on a Micra using a £5 coil pack from the scrappies. Keep on top of the oil changes and these kinds of engines rarely go seriously wrong.

Nads02

Original Poster:

120 posts

37 months

Saturday 24th April 2021
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Pastie Bloater said:
Happy days, cheapest misfire fix I ever had was on a Micra using a £5 coil pack from the scrappies. Keep on top of the oil changes and these kinds of engines rarely go seriously wrong.
They're great engines, planning to keep it until the engine explodes, if it does. But I change my oil with oil filter every 5k miles and service every 10k so it should be good for a long time