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Oil fouled sparkplugs

KLA33E
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KLA33E Contributor

KLA33E

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Posted

Hello fellow Skyline owners!

I’ve had my car in the garage for 6 months now, during winter time. 
Before I put it off I had the car remapped.

During the mapping session the car suffered from intermittent missfires on higher rpm. 
Then when I was done and started the car to drive home the car only ran on 5 cylinders. We did some fault searching, narrowed it down to cylinder 3.

Then all of sudden after we swaped coilpack 3 & 1 around, it worked again. 
The coilpacks used at the time were Splitfires (5 years old).

One of the things I wanted to do was to upgrade the ignition system, so I did.
I Installed VR38 smart coils. Also swapped out the sparkplugs (ngk bcp7res) gapped at 0.7mm.

This is when I found out that all of my old sparkplugs were very black and a bit wet. 
I originally thought this was a tuning or fuel realated issue since it was affecting all the of the cylinders.

This week I started her up.
after about 40 minutes of total running (idle) I removed to check my new plugs..

All the sparkplugs have what looks like fresh engine oil on them. The threads are clean, just on the base and half around the center electrode, just as the previous ones too had.

Earlier sparkplugs i’ve had replaced has never looked like this and I find it odd that it’s like this on all the plugs.

Do you guys have any ideas what would cause all the cylinders to have oil in them all of sudden? 🤔

Will upload a picture so you can see too.

 

The car is a R33 RB25DET

Car has uprated turbo,injectors,maf,ebc.. Running a apexi power fc.

Unopend engine. Done about 90000km

4F64955E-B677-4C07-9D05-73C95342FB87.png

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PLYNX Mentor

PLYNX

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Posted

 Hmmmm could be a bunch of things but I would first start with a leak down test.

This will let you know if there is something physically wrong with the engine

You could be looking at valve stem seals, turbo oil seals and even piston rings

Coil packs do fail so get em checked as well as your coil pack loom cause it might of been faulty out of the box.

blind_elk Grand Master

blind_elk

Posted
Posted

I wouldn't be surprised if the "wetness" is actually unburnt fuel. Next to no point starting the engine and letting it idle for 40 minutes - it's unlikely to get up to operating temp, with the result that it runs permanently rich (because it's cold).

Also, try opening out the gap, to around 1mm (factory spec is 1.1mm).

SteveL Mentor

SteveL

Posted
Posted

As above, could be fuel.   Have a sniff of the plugs - oil and fuel have distinctive smells.    If the engine was burning oil I'd expect the plug tip to be black and oily, not largely 'clean' oil.   Also the car would be blowing white smoke at idle with that amount of oil.

I have seen something like this once before on an RB that had leaking rocker cover gaskets.   Oil was 'pooling' in the spark plug wells and when the plugs were removed the oil was making its way onto the threads and the end of the plugs.   

KLA33E Contributor

KLA33E

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On 06/05/2021 at 12:11 PM, SteveL said:

As above, could be fuel.   Have a sniff of the plugs - oil and fuel have distinctive smells.    If the engine was burning oil I'd expect the plug tip to be black and oily, not largely 'clean' oil.   Also the car would be blowing white smoke at idle with that amount of oil.

I have seen something like this once before on an RB that had leaking rocker cover gaskets.   Oil was 'pooling' in the spark plug wells and when the plugs were removed the oil was making its way onto the threads and the end of the plugs.   

Yes, it’s strange that it’s on all the cylinders. 
threads are all clean, it’s just around half of the tips on all the plugs..

Wideband is reading 12.3 at idle when cold, then when warmed up it sits between 14.5-14.7 

i’ve also noticed that since fitting my power fc the fuel pump isn’t priming for as long as it used to, but haven’t given it to much thought. 
I can mention to that the fuel pump is upgraded to a tomei unit.

KLA33E Contributor

KLA33E

Posted
  • Author
Posted
7 hours ago, mlr said:

Is it smokey

Turbo seals?, blocked PCV?

What does your intake pipe and IC look like

I accidentally kinked a PCV  hose once and it pushed ALOT of oil, was really smokey though

No it rarely smokes, only when I cold start it in colder/moisty weather.

the turbo is a HKS GT-RS unit which I replaced 2years I also replaced the Pcv-valve with a new one.                  Intakepiping is clean, looked in my catch can the other day. Not a visible drop of oil.

Im starting to lean towards fuel, it just looked very much like oil in my opinion.

I don’t know if partly combusted petrol can get a orange/yellow look to it?

 

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