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[Lizzie_Zoom]

Whilst servicing my miggy, a plug lead (the shortest , right at the back of the engine; yes that one!!) fell apart whilst changing the plug. Tried to repair, but the engine was lumpy and the engine management light came on.

Bought a set of replacement leads from a local Vx breaker (just £15!) and fitted the replacement lead.

Engine management light now has gone out, but engine runs still lumpy. Also once becoming hot blue smoke appeared from under the car, and there was a smell of burning; electrical perhaps.

Any ideas from you guys please?

[dbug]

Firstly welcome back Lizzie 

Sure its electrical - possibly leaking cam cover gasket?

[Lizzie_Zoom]

Thanks dbug

Yes, that's a good thought.  I will investigate, yet again, tomorrow.

[Entwood]

Welcome back

Blue smoke is usually oil, electrical cable burning is usually black smoke, but sometimes white

Lumpy running + blue smoke ... as said possibly cam covers, would also fit with the plug lead disintegrating if its been sat in a puddle of oil for a long time. New lead may well not work correctly if the plug well is that full of oil .....

Time to check those plugs wells methinks ..

[Lizzie_Zoom]

Thanks Entwood

All the plug wells were perfectly dry. But of course I suppose an oil leak could be elsewhere

[symes]

check the connector inside the plug cap is a tight fit on top of plug-that was problem on mine also check you havent split a vacuum pipe at the back of engine when you pulled the leads out-(done that before)

[Lizzie_Zoom]

check the connector inside the plug cap is a tight fit on top of plug-that was problem on mine also check you havent split a vacuum pipe at the back of engine when you pulled the leads out-(done that before)

Thanks

You have given me some fresh ideas

[symes]

Thats from my problems on silver shed

[robson]

Sorry cant help much Lizzie but good to see you are still with this group.I thought that you may have changed to a BMW or something. Ron

[feeutfo]

Hi Lizzie, any oil in that pot?

New leads needed, at least.

[Lizzie_Zoom]

Sorry cant help much Lizzie but good to see you are still with this group.I thought that you may have changed to a BMW or something. Ron

Thanks Ron

BMW? No way.  It is an Omega................or a new Merc E Class!

[Lizzie_Zoom]

Hi Lizzie, any oil in that pot?

New leads needed, at least.

No oil in spark plug holes Chris.  Already replaced one lead that was broken.

Thanks.

[Entwood]

I wonder if there are two other possibilities .. both of which would point to the DIS pack ....(I guess you must have a DIS pack as you have leads !!)

Failure of the lead may have caused a problem to the DIS pack which has now failed, so giving the misfire

DIS packs are known to fail due to corrosion of the cores .... if the DIS pack had a problem would that in turn possibly cause the lead to fail ??

Having checked leads/plugs/plug wells my next check would be DIS pack....

[Lizzie_Zoom]

I wonder if there are two other possibilities .. both of which would point to the DIS pack ....(I guess you must have a DIS pack as you have leads !!)

Failure of the lead may have caused a problem to the DIS pack which has now failed, so giving the misfire

DIS packs are known to fail due to corrosion of the cores .... if the DIS pack had a problem would that in turn possibly cause the lead to fail ??

Having checked leads/plugs/plug wells my next check would be DIS pack....

Thanks. Will do

[Kevin Wood]

A couple of points. If it's running with a misfire one of the cats is going to get extremely hot. Maybe this explains the smoke from underneath.

It could well be that the coil pack has died as well. The extra stress from firing into an open circuit might well have done for it. Worth checking for a spark at cylinders 3 and 6.

It might be that the spark plug on the misfiring cylinder was soaked with fuel. I'd expect it to have cleared but might be worth drying it out over a gas ring - or just replacing the plugs if they are not new. (I guess they are if you were disturbing the lead?) If you've got the old one it might be worth swapping that back in just to be sure you've got a dry plug in that cylinder. Of course, removing the plugs and checking which ones are wet might be useful, just in case it's not the cylinder you think it is that's mis-behaving.

Also worth double checking that the leads are really on the right connectors at the coil pack. You wouldn't be the first to get the leads on @rse about face, because the correct connections are not how the leads go on logically (until you think about how a wasted spark setup works).

Finally, it's worth a paperclip check just to find out why the EML came on. A misfire doesn't normally do that on the non-DBW cars, so there might be a clue there.