Spark Plug Mystics (Can someone read my spark plugs?)

Cylinders 1-4, bottom to top. They are out of a well running 944 with ~5,000 miles on the plugs. It looks to me that the end cylinders are rich/cold, and the center two are lean/hot? 

The rear one looks a little "burnt oil" contaminated to me. But I agree, the outer two look a little richer than the two center ones.

I'd start with something like this: https://www.onallcylinders.com/2012/12/20/reading-101-how-to-read-your-spark-plugs/

But my first instinct says, if you think they are worn/damaged/not doing the job, just change them. Especially with plugs because they aren't pricey at all.

I'd say the center ones look good and the outer ones look a bit rich.

z31maniac said:

I'd start with something like this: https://www.onallcylinders.com/2012/12/20/reading-101-how-to-read-your-spark-plugs/

 

But my first instinct says, if you think they are worn/damaged/not doing the job, just change them. Especially with plugs because they aren't pricey at all.

Ive tried to read those charts, but couldn't come to a solid conclusion on my own. They will get replaced either way, I just want to verify that this might be something I should look into (why are the outer two more fouled compared to the inner two?). 

I think injectors for cylinder 1 and 4 need to be cleaned/tested they may be leaking.

Swapping injectors between 2/3 and 1/4 can help identify if it is wiring/driver issue or an injector issue (the ECU has been known to have issues with bad solder joints or other problems)

Use new plugs to get a proper indication.

TR7 said:

z31maniac said:

I'd start with something like this: https://www.onallcylinders.com/2012/12/20/reading-101-how-to-read-your-spark-plugs/

 

But my first instinct says, if you think they are worn/damaged/not doing the job, just change them. Especially with plugs because they aren't pricey at all.

Ive tried to read those charts, but couldn't come to a solid conclusion on my own. They will get replaced either way, I just want to verify that this might be something I should look into (why are the outer two more fouled compared to the inner two?). 

Perform a leak down test and a compression test if you're worried about engine health.

But if the engine is running fine now, I suspect it's not a big deal. Sure the plugs don't all look identical, but it wouldn't worry me.

Looks more like oil than richness, and you have crap in your fuel (deposits on center plugs). 

You can't read lean/rich unless it's a gross problem if the engine has run under any condition that you don't want to examine. For wot reading you need to do a pull and shut down and don't let it idle. Then you can read the threads and the ground strap for timing/fueling.

That being said... Plugs that idle near stoich should look almost new with just a light tan color.

In reply to Paul_VR6 :

When I was running 2 stroke motorcycles that is exactly what I was taught with the additional steps of warming it up and then putting in fresh plugs and run hard .

Braden