Okay, I had this problem before, but it occured infrequently. It's happened twice in the last 5 days now. (I just installed my turbo setup this week). Anyways, the car will throw a check engine light sometimes, so I'll shut the car down and pull over, and try to pull the code, but the moment I restart the car, the check engine light disappears. Anyone have any idea what it could be. I think it might be the o2 sensor. I know on the dyno the wideband could barely read my a/f ratio. The car was running pig rich 10:1 or better, the bosch wideband could only read above 10:1.

 

How much boost?

You realize that you're not supposed to start your car to check a CEL right? You just turn the key to the position just before you turn it on with the paper clip in the connector and then count the flashes... you don't start the car.

 

.5 bar
Hmm, maybe that's part of the problem, either way the code is gone.

 

Does it go on when you hit boost?

 

nope, not yet anyways.

 

do you still have your cat?

 

ahem...no

 

Do you have check valves for the MAP sensor? If so, you may need more.
I've heard MISSING LINK works well.missing link

 

No, I don't need a missing link. I'm not running an FMU or the "Hack". As I stated before it does NOT throw the code under positive pressure.

 

without a cat, I have sometimes heard of a very random CEL during longer drives and on the freeway. the CEL's you got weren't at those times were they?