Flooding/Boost Issue

[Zimm]

early last year i was able to run 11 - 13 pounds boost (rb25 turbo) no problem with out hesitation but late in the year it started running more rich and now this year i can only do bout 9psi of boost before it starts hesitating, im wondering if from the car running rich its effecting my boost?

[Skym]

Lean (over 12.0:1 A/F ratio) usually starts to = drop in boost level.

You would need to look at sensors, etc via stock ECU (using Nistune tuning software), as could be a few things causing it.

It could be boost cut (airleak infront of MAF), ECU pulling ignition timing, faulty coilpack or coilpacks (ECU pulls ignition timing and adds more fuel due to it thinks engine is knocking), etc. Or could be worn sparkplugs.

Sometimes the internal wastegate actuator bulb is faulty and the result is it opens wastegate on back of turbo, peak boost level drops. Also get rattling sound on back of turbo (internal wastegate flap / cap for hole moving around at idle).

[Zimm]

so in boost my a/f gauge is at 10.0 - 10.5, is this good or is this to much fuel?? and i can still boost more then 10 but if i do it just hesitate's.. im not to sure how to check for boost cut but im going to check my plugs... what plugs should i be using? and ill check my coil packs

[Skym]

10's is the result of what factory use on main fuel map (also known as high octane fuel map) with stock engine. It can go richer (9's) on knock fuel map (also known as low octane fuel map) and ECU pulls ignition timing. Switch to knock maps is sometimes triggered by a bad batch of fuel (it does happen at some service stations), low octane gas, poor ignition. Sometimes it's as simple as something knocking on engine (creating excessive noise). On modified engines it's usually the ECU tune is not correct and mix with bad batch or low octane gas.

I would suggest you read the FAQ section of NGK sparkplug website -

http://www.ngksparkplugs.com/tech_support/spark_plugs/faqs/index.asp?mode=nml

The info you need to know is the spark plug you use depends on hp (change heat range every 75-100hp). Or if engine is richer (hot sparkplug like PFR5A is used at factory) or leaner (cold sparkplug like PFR6A can be used with intake, exhaust, small turbo upgrade). Heat range (PFR5A, PFR6A) is based on cylinder temps and reading tips of sparkplugs tells you alot about what's going on inside cylinders (see above link for how to read a sparkplug) and if your sparkplug is correct or not.

Sparkplug gap around 0.8mm if missing at higher rpm (usually damages coilpacks x2 or so if it misses at higher rpm, as it did on my car).