1g leaning out at idle and passed 5,000rpms under boost

[GettinPaper]

Too start it off my mods are dejon MBC set at 12psi,a 3" straight pipe exhaust(ported the 02housing and turbo hotside for creep it holds steady boost to redline), dejon hard intake pipe and a walbro 255. I have zero boost leaks also. I have a AEM wideband and it reads 16.5 to --- at idle. And 10.0 under boost until 5,000 Rpms then it shoots up to 12.8-13.5.. What would be causing me to lean out at all?? Any help is appreciated.. Thanks

 

[mercaholik]

Besides everybody else's good ideas just thought I would tell you about the time my intake valve rocker arm was no longer in its home. It was just sitting in the top of the head, I pulled the v/c after chasing a very strange stuttering issue. Turned out one of my intake valves want even opening. Right at 5000- 5500rpm it would stutter every time. I also had a bad lifter that I think may have been the cause of it popping off. Apparently it's happened to others before cause I looked it up on here and that's when I found my answer. Also no that filter sock doesn't look to good, of any fine sediment made its way to the injectors they, or the screen on top off them might be clogged. Easy to pull them and squirt them into a container to see.

 

[mean4g]

if your car misfires the wideband will go extremely lean. The cylinder is pumping out mostly air and causes a spike in the AFR... It is a false lean indication FYI.

 

[mercaholik]

I've heard some not so great things about the aem wideband, but no first hand experience. You can hook up a sniffer to the tail pipe and see what the a/f ratio is, if your sputtering then it has to be mis firing. You need to verify your actual problem, and let's try to get a check list of what you checked and how please.