Just removed my heads from my VG30ET after the timing belt incident occured. Just with 2k miles on the car, the pistons have a black coating on them. I did some research, appears to be indicative of running too rich. This is possible even though I have an A/F guage. Of course I hear the simple Autometer electrical guages are not accurate. I maintained a lean reading when running. I will be going with a better way to meter my A/F.

Just wanted to check in about piston appearance and see if this is consistent with what I've learned or should I be worried about something else? Thanks for input.

 

Lean mixtures cause high combustion chamber temps, if your lean enough you could have detonation, which could be leaving the marks.

 

You need a wideband o2 and a good guage to get an accurate a/f reading. You are running rich if you have carbon build up (black stuff) on your pistons but that's not necessarily a bad thing. Turbo cars should be tuned a little bit rich anyway. You might be running too rich, but there's no way to tell without a wideband o2. How did you tune your car in the first place?

 

I tuned it on by the "feel" of the car. How it was idling, running, accelerating, returning to idle after acceleration, smootheness through rpm band, and smoking. My Autometer guage I thought was okay, but it seemed to run lean regardless of how high I bumped up the fuel pressure.

Simple response to how I tuned...I guessed. I'm running Live Edit and installed a program that ran the car best through the above mentioned criteria. I will be getting a Wideband, looking at the new NGK unit. Not sure if best or cost effecient though. I'm posting pictures on my Cardomain page tonight. If anyone's got a moment, take a look. It's low res though. Black coating doesn't seem too thick. Once I get everything back together, I hope to be able to do a better tune. There's just no one around me who knows anything about Live Edit or has a dyno to really get me where I need to be. It's like I've got all the tools I need to produce the power, just no way of "accessing" it. Thanks for feedback.

http://www.cardomain.com/ride/329804/5

 

Pics are up using the link provided in last post.