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[perfferle]

Hi folks,
Please let me know what to check for an engine misfire that started quite suddenly today and is constant from idle throughout tht rev/RPM band.
The 'rotten egg' smell is present so can i also assume that it is not an injector?
Please help.

Thanks,
Stephen

[MutantCav]

Blocked cat could be your culprit??

[Entwood]

Check your plug wells for oil or water, check HT leads are correctly seated.

As you don't mention the EML I'm assuming it is not on ??  but does illuminate before you actually start the engine ??

A misfire with no EML is usually a "spark" problem .. or rather .. a lack of spark !!!

So, worst case ...   DIS pack
or     HT Leads
or Spark plugs

BUT plugs /lead problems can be caused by oil leak from cam-covers ..

HTH

[hotel21]

Standard first question is what fault codes, if any, are available?

If you do a search in the Maintenance Guides section for paperclip test, you will see whats needed....  

[dbug]

Check your plug wells for oil or water, check HT leads are correctly seated.

As you don't mention the EML I'm assuming it is not on ??  but does illuminate before you actually start the engine ??

A misfire with no EML is usually a "spark" problem .. or rather .. a lack of spark !!!

So, worst case ...   DIS pack
or     HT Leads
or Spark plugs

BUT plugs /lead problems can be caused by oil leak from cam-covers ..

HTH

Agreed usually HT issues

[perfferle]

Hi,
Thanks for the suggestions. I just completed the 'paperclip' test and here are the results:
12
135
31
Please let me know if anything is apparent from these codes.
YES There are leaking rocker gaskets BUT this has been for some time now (The job to repair is planned). This misfiring fault started very suddenly today - do you think it can still be HT leads?
Thanks
Stephen

[MutantCav]

The oil leak if left for some time can damage the ht leads, or even the dispack...

Thought the egg smell might be caused by cats...I'm assuming I'm wrong...

[MutantCav]

12 is just the number that comes up at the start and end of the test...ignore it...31 is no signal from crank shaft sensor, I assume you did the test with the engine not running...if so ignore it, or redo test with engine running to make sure it goes away...

135 I would have to look up lol

[Entwood]

The leaking gaskets often slowly fill the plug wells without you realising it, they are VERY deep, eventually they are so full the ignition at the plug breaks down and the misfire starts. As the V6 uses a "wasted spark" system you usually lose the spark to 2 plugs at the same time, so the misfire feels worse.

How do I know this .... you are describing EXACTLY the problem I had over xmas !!! My centre plug drvers side was so deep you could not see the top of the plug    Luckily a breather clean/gasket change (I had the bits to do the job but just hadn't got around to it) sorted things out in time for new year, I was lucky ... plugs / leads were still OK

HTH

[perfferle]

Hi Chris,
Dammit! This does not sound like a quick fix.

Do you figure that once I sort the gaskets and the oil is dried up, the HT leads would be ok?
Thanks,
Stephen.

[perfferle]

Hi Entwood,
Would you happen to have the rocker cover gasket part# for both banks? and what parts would i also require to get this job done?

Thanks,
Stephen

[MutantCav]

Best way to see if leads are fried are to replace them if you have a spare set...or remove the offending leads and plugs with the oil in suck the oil out with a pipette and or some cotton wool buds...then reassemble and see if the misfire has gone...if it has get the gasket sorted quick to stop anything failing!

[Entwood]

All you need is in these 2 guides

http://www.omegaowners.com/forum/YaBB.pl?num=1152598350

http://www.omegaowners.com/forum/YaBB.pl?num=1152564281

There are other guides that might help .. plenum removal, scuttle removal etc etc .. have a good read around

[albitz]

and clean the breathers and change oil every 4,000 ish to stop it happening again.

[Marks DTM Calib]

A sudden change on leaking gaskets is generally a sign of something letting go......shorting the leads out with oil can knacker the leads and puts extra load on the DIS pack