Spark Plug Analysis

[Clip]

Here's pictures of cylinder 5 after 500 miles on 10k mi fresh engine. Cylinder 3 looked similar, but a lot less buildup.

Ran 15 degrees advanced timing with 89 octane. I've returned it to 10 degrees at the moment.

Looks like a ton of (carbon?) buildup and the insulator's chipped slightly (detonation?) but I haven't heard any knocking, just a terribly rough idle. Also looks like the electrode has been worn away at the back but mushroomed up front.

Replaced with six fresh NGK V-powers, all plugs now and previously were gapped at .044.

Can anyone tell me what this is or what's causing it?

Thanks!

 

[kotu100]

http://www.aa1car.com/library/reading_spark_plugs.jpg

that might help. looks like ash deposits.

not sure what your problem could be, espcially since its not in all cylinders.

 

[Clip]

http://www.aa1car.com/library/reading_spark_plugs.jpg

that might help. looks like ash deposits.

not sure what your problem could be, espcially since its not in all cylinders.

already looked at the one in the back of a haynes manual i had laying around

thanks for the advice!

 

[kotu100]

does it still idle rough with the new plugs? any idea why it idles like that?

 

[HommerSimpson]

Id like to see a compression check when cold first thing in morning after sitting.. and after a normal drive.

also after it has sat over night.. id take a look down each cyl see if any wet..

im thinking injectors are washing out clys and thats aluminum ...

 

[jdub]

Clip - that looks like it's been subject to high temps combined with oil contamination.
The high temp can be explained by the advanced timing...what heat range plug are you using?
How much boost?
Did you replace the guides during the rebuild?

 

[HommerSimpson]

what kinda shape are your plug wires in ?

 

[funky_monkey58]

Why are you running such a wide gap? I run a .024 gap and very few spark issues and in high boost I have been known to go to a .022-.020 gap.

How clean are all your injectors?

 

[Clip]

idles smooth as peanut butter with the new plugs right now. no boost (NA) and as for the guides, i bolted down a rebuilt head from cylinder heads int'l. i'm thinking that's where the problem might be.

I'll get back to you guys on the plug model number and heat range, plus compression check saturday. Plug wires are brand new NGKs. as for gap I've just met TSRM specs for the GE, and I'm also guilty of not having the injectors flow-tested during the rebuild (stock GE as well)

 

[Clip]

spark plug is NGK bcpr5ey-11. where can i find the heat range?

 

[jdub]

The "5" indicates the heat range...for NGK plugs: Lower # = hotter
You are running a hot plug compared to the turbo...Yes I know a 5 is stock for a NA. I would give one step colder (6) a try with a 0.038"-0.040" gap.

Keep your timing at stock.

A compression test is a good idea.