First Spark Plug Check (~2000 miles) [big pic]
 

Well, the weather is nice and so I took the chance to pull the plugs to give them a looksee after around 2000 miles, maybe less. It's been over a year of driving since the engine was rebuilt and I figured I'd give it a look.

http://www.theexitwound.com/944/plugs1to4.jpg

The gaps look neat and clean, but there is something of concern on cylinders 2 and 4 that I'd like some input on.

http://www.theexitwound.com/944/plugs2and4.jpg

There seems to be either a layer of decay that's peeling away, or it's a layer of gunk caked on. I couldn't get it off though by scraping. What does it look like to you?

The car was run with presumably the original Oxygen Sensor for the first 500 miles or so, then it was changed with a new Bosch universal.

thoses cylinders are hotter then the others. air pockets not bled properly.

I don't think its related to the O2 sensor because the plugs would all be similiar. It is a heat issue as mentioned. When you had the engine rebuilt, did you send the injectors out to be cleaned and balanced? You may have a "lean" issue on cyl 2 & 4 and causing overheating.

Try a higher octane gas or switch octane level at each fill-up.

I've been using a couple of ounces of Lucas fuel treatment ever so often. It lubricates the fuel pump, cleans and improves mileage.

GL
John_AZ
1988 924S 59K + 1987 924S 113K DD