Who here reads spark plugs?

[orange150]

Pulled the plugs today on the 4.2 and there was a fair bit of ash build up on them. Is this from running too lean? I JUST went through the 2150 and cleaned as one of the squirters was clogged.

I think I got these in order:

Plug #5

#4

#3

#2

#1

I did not get a pic of 6. I started at six and worked forward and it was perfect looking.

 

[YOUNGBLOOD13]

The light colored ones look lean. The ones with the heavy, chalky deposits are most likely poor fuel, fuel additives, and/or oil in the cylinders with high temps. Try fresh fuel, check for vacuum leaks/go up in jetting, try different heat range (colder)

 

[orange150]

Hmmm. Poor fuel could be an issue from it sitting for a few months, especially during the rain.

The lean condition is funny as I've always thought I was over fueling. I'm already running .50 jets, where most people run 48s or 49s. PV is an 8.5 too which is a little bigger than most.

 

[Jason W.]

I would check compression on cyl 5 and 4, with plugs out of course, just to see

 

[a_kelley]

Coolant in cylinder will also cause deposits...

 

[orange150]

Wouldn't that cause the plugs to look "wet"? Similar to too rich

 

[tsconver]

2 3 and 4 look fine.

I would compression check 1 and 5. Also check the wires and cap and rotor. Deposits like that are usually misfire.

Plugs should be a ashen brown when all is good. If they are pure white then you are lean and running hot. Dark brown is rich and a bit cold.

Here is a good link Reading 101: How to Read Your Spark Plugs - OnAllCylinders

 

[junkxj]

Coolant in cylinder will also cause deposits...

That's what I was thinking the 2 bad plugs looked like, coolant in the cylinder.

 

[a_kelley]

That's what I was thinking the 2 bad plugs looked like, coolant in the cylinder.

@orange150 it's simple enough to do a leak down test and prove yes/no on compromised head gasket to water jacket. Especially on just the questionable cylinders.

 

[junkxj]

@orange150 it's simple enough to do a leak down test and prove yes/no on compromised head gasket to water jacket. Especially on just the questionable cylinders.

This. Especially with the 2 bad plugs coming from adjoining cylinders.