B235R spark plugs - warning distressing image included

[carrera]

Well, after spending so much time rescuing 9-5's over the past few months my daily has been running a bit rough on light to moderate throttle. Full  is OK.

The car has been dealer maintained from new, but it missed on a service at the time of the last MOT, it would have been due only on time, not miles. I have been getting occasional 1312, 1334 and 1391 error codes which went along with a 1310 which was easily solved by fitting a new piece of hose that wasn't perished

As progress with the green rescue is now halted waiting for paint and body panel painting, I finally got round to giving some love to the blue car.

For once I decided to look at the easy stuff and pulled the plugs out. (the genuine DI is fairly new and in good condition)  PFR6H 10 are fitted

Oh my



I will clean them up for now so I can drive home, but what is all that build up that looks like lead ??

I have checked the gaps and they seem to be consistent at 0.9mm

Are these what the long life plugs look like when the finally get replaced ?  Any other thoughts ?

[sgould]

They do look a bit cruddy.  Do you use the same filling station? 

I have this photo of the plugs removed following a DI failure and a whole week of bad misfiring and engine lights.  I was on holiday in Italy and tried to keep the car going until I got home, but in the end it got too bad and I had to unload the boot and get the spare DI out...

[carrera]

Well, they look quite nice to me.

The car definitely seemed to run better with clean plugs, this was particularly noticeable at lower revs, say 1300 to 2000 where I could feel it running a bit rough before.

After cleaning I rechecked the gaps and they were 1.0mm, the residues were clearly coating the electrode on all sides

I have looked back over the service history. plugs were changed when the DIC was changed at 307,000, and mileage is now at 326,000 so 19,000 miles when the service interval is 36,000.

I thought all was OK, but after following a particular pattern of driving the flashing EML came on (fully warm engine, idle at lights, accelerate at medium throttle changing at around 3000 rpm) which I believe indicates a misfire which is so bad raw fuel is being dumped from one or more cylinders. That flashing light remains on for 5 or more seconds even when the engine is on overrun,i.e no fuel is being provided at all.  A period of WOT or idle / minimal throttle turns the flashing light off. Occasionally a code will be stored as above.

The blue car needs an engine refresh, she's consuming oil and is still on the original piston rings. Valve guides are probably worn too. I was suspecting a build up of oil in the head at idle then gets pulled down the valve guides when accelerating and the engine management system sees the oil resides as unburnt fuel.

Could the build up on the plugs be burnt oil residue ?

[fka]

Just given mine it's annual service today. About 8k on the below and only a very slight gap increase on 2 plugs (BCPR7ES)..
All good but I have just discovered, whilst warming up to do a final check on the oil level, that I still have an occasional misfire 

[phoenix]

Do they resemble any of these?

https://www.verrill.com/moto/sellingguide/sparkplugs/plugcolorchart.htm

[carrera]

That's a good chart, similar to the old Haynes coloured one I carry round in my head

They looked like the ash fouled photo, which makes a lot of sense. Cleaning the plugs opened the gaps up to normal and the light fluttery misfire I was having is now gone. The engine is consuming oil too, which I assume is entering the combustion chamber by the valve stems, but no blue smoke unless going for