Hello,
I wonder if any of you kind folk can help shed light on an ongoing problem please..
Ive had my car a year now, when i first got it I neeeded to replace a coil pack, did so then it ran fine.. Also Changed the plugs to Champion Eons, all fine for a couple of months then started missing under load again, changed the other coilpack (for second hand one, still has no cracks)all seemed fine. Fitted an induction filter, dawes valve and a gauge, boost seemed low but could increase with dawes to abt 1 bar, it ran fine for a couple of months or so, then it started missing again under boost, changed the wiring loom to the coils as old one looked tatty and changed the plug leads and the plugs again for the same eons not thinking they could be the issue. The problems been getting steadily worse to the point where it was sorta missing on idle, its been driving me mad..
I read my S40 manual and it stipulated the plugs should have a 0.75mm gap the eons had a gap of .95mm (were designed for the T4). I took the plugs out to bend the electrodes in and noticed that on cylinder one it had clear oil with some black cloudy liquid also over the ceramic, thread and electrode, the others were ok with no oil on them at all. I bent the electrodes in, cleaned the plugs up and for the first time in months my car boosted right through with no blips, felt rapid, infact the fastest it ever been reaching 0.9bar without the dawes as opposed to 0.6 when car was running well with the eons in and no dawes on!!! It still felt a little rough on idle but all four cylinders were detonating, changed the plugs yet again for gen volvo plugs( the eons I removed were freshly cleaned the day before and still that first plug had oil on it) and now it was smooth on idle, couldnt tell the engine was running !!! AT LAST !

Untill today ): the car started hesitating again under boost and i bet theres oil on the first plug again.... Its something big isnt it ??????
Funny thing is, it never ever smokes,hasnt lost any oil at all, engines only done 72 k; oil wasn't on any of the plugs with the first two plug changes whilst having the same problems, thats only untill the recent plug change ( changed the plugs now 3 times in 10k)...
Could having plugs in for nearly 10 k with the wrong electrode gaps damage the internals, surely if there was a gasket leak there would be smoke, read something about a valve that allows engine gases into the mix ??
Any advice would be brilliant, at my witts end, Love my S40 dont want it to die !!!! Cheers

 

Is the oil going in by the coil/wire and getting on the threads when you take the plug out?
Oil cap seal leaking?
Can you see oil in the top of the plug well?