hello im a newby and honestly don't kno the first thing about turbo'd vehicles but I bought an evo.. well a couple months ago my boost went to about 15 pounds then immediately dropped back down to 11 and held. I found a loose vaccum line put that on tightly now it goes to 15 16 pounds and hold. when I bought the car it was getting higher then that not sure how much. but now my afr when im just normal driving bounces between 13 and 15.5, when im getting on it it goes around 12 or 13. if I completely let off it immediately goes up and all the way in the red and it reads ---. obviously my fuel mileage is ridiculous I need to get it fixed because its my only transportation at this time please help. ill give you as much information I can if need be. thank you

 

While cruising, the AFRs will bounce around the numbers you posted which is normal but as far as being in the 12s under boost is enough to say that I wouldn't push it until I had a Evo specialist shop have a visual look at everything and check out the tune.

 

On cruise, it will bounce alittle, up and down but averages 14.5-14.7. When you let completely off the gas while in gear, it will go full lean due to close loop. When you are WOT, you should see the numbers go down to high 10s to low 11s. Typical is 11.1ish depending on tune really. If you're seeing 12-13, you might be lean. However, its also necessary to know what boost pressure youre hitting. Best bet, as mentioned, is to take it to a good tuner.