Can someone read my old spark plugs?

[19jacobob93]

Just changed my 40,000km old Bosch iriums for factory motorcraft (really denso) ones.
Some of them had a hard shiny black coating on one side, and a white powdery coating on the other.
Some only had the white powdery stuff
A couple also had a bit of oil on the thread of the plug

I shone a light through the hole and it looked like there was a lot of carbon buildup on the top of the pistons. I thought I've been hearing the engine pinging under acceleration recently so maybe this is why?

 

[Revving2Redline]

Without looking up solutions my guess is too low octane and maybe a clogged fuel part. Alot of black is probably excess carbon or a valve guide/seal leak. Iridiums run a bit hotter which may give better mpg, but would cause burn prematurely too. Make sure to run quality spec oil and maybe a fuel cleaner with PEA to get it back in order.

 

[xnicke]

I wouldn't worry about it. It could possibly be a slight oil leak from the valve.

 

[19jacobob93]

Originally Posted By: Marco620
Without looking up solutions my guess is too low octane and maybe a clogged fuel part. Alot of black is probably excess carbon or a valve guide/seal leak. Iridiums run a bit hotter which may give better mpg, but would cause burn prematurely too. Make sure to run quality spec oil and maybe a fuel cleaner with PEA to get it back in order.


Thanks! Sounds quite accurate actually, I've been running caltex 91 for the past year as I get discount on it but I've been advised against using it by someone who told me it's not very good stuff. I've put some bp 91 and a bottle of valvoline injector cleaner in today and I'll fill it with shell vpower 98 when fuel prices drop in a few days.

As for the clogged fuel part, spot on again! I changed my 14 year old fuel filter the other day and when I opened it up it was in very bad shape inside. It was clogged with black sludge and I'm surprised fuel could pass through it!

If the iridiums burning hot, they could be causing predetonation and the pinging noise I hear

Just gave it an oil change today with durablend and half a bottle of mos2

Thanks again for your accurate reply!
I might try something stronger to clean the engine out soon

 

[Rolla07]

Only 40k kms on a set of iridiums??!!! Im at 182k kms and still on original set...i think you could of run them 100k or more...are u instructed to change them more often?

 

[19jacobob93]

Originally Posted By: Rolla07
Only 40k kms on a set of iridiums??!!! Im at 182k kms and still on original set...i think you could of run them 100k or more...are u instructed to change them more often?


Haha I know they're good for quite some miles but I heard Bosch spark plugs can cause the ECU to throw a code out in this engine.
They seemed to be working fine but I had a look at them and they looked pretty nasty. Found some factory OEM ones at $16 for 6 so I thought I'd just get some anyway!

 

[Rolla07]

Great deal..true bitog'er just wanting to find something to work on am i right? LOL

 

[bulwnkl]

How much oil does the engine use?

In the spirit of throwing out whatever comes to mind,

--
The black is from the oil you're burning. The white is, too; it's the organo-metallic additive package.

 

[asand1]

Looks like it's burning lean and using some oil.

 

[19jacobob93]

It does use a bit of oil which I think is because of the after market metal pcv valve I installed. It never used to use a drop with the factory plastic one, and someone asked me if it's started using oil now and I said no it never does.
Checked my oil and it had used quite a bit!

 

[circuitsmith]

OEM plugs are almost always the right way to go.
The Bosch might look bad simply because they are not really the right plug for this engine.
I would take a look at the OEM plugs after they have 10,000km on them before worrying about an engine problem.