Okay guys I have an Evo8 with AFC version One, AEM Intake, Turbo XS MBC, Walbro 255 fuel pump, Ground Wires, Ralliart Spark plug wires, NGK one step colder plugs(getting ready for 35 shot) and open downpipe... My problem is my check engine light came on and my car hits fuel cut at about 4k and it sounds like my turbo is spooling a lot louder and my car is running rich as hell. I thought it might be my back o2 sensor but even if i reset my ecu the SES light comes right back on... I have been runing open downpipe for a week and the SES light hasnt been a problem until now so i dont think it could be the o2. thanks for anyhelp

 

you need to get a scanner. if you dont have one, go to autozone or pepboys and they will scan your code for free. After you find out what the problem is, then you can find the problem. It is most likely a o2 sensor problem but i would get the code scanned right away. i also suggest that you get a scanner. I am using a auto xray..it is not the best but it gets the job done. i have diagnosed many problems with my cars

 

Those are the patent signs of a loose intercooler coupling. You are running rich b/c air is getting out somewhere between the throttle body and the MAF and there is no air to be burned with the fuel. The turbo is spooling loud b/c there is extra whistiling where the air is getting into or out of a loose connection. Check all of your hose clamps and make sure all your vacuum hoses are correctly attached.

 

My ic piping is all intact any other ideas?

 

bump

 

You lost me on the open downpipe. IF it's open then what the hell does the O2 sensor is obviously setting off a CEL, it doesn't see any exhaust!

 

why would it take a week for the ecu to notice this? and now the ses light wont go away

 

like i said...the only way to diagnose the problem is get it SCANNED by either autozone or pepboys....that will be the only way to find out what the problem is

 

Because inactivity codes for the rear O2 have a certain criteria they must follow in order to trigger a fault and even then it's usually a two step process. as everyone that has a CEL for the rear O2 and they will tell you that it goes away for a while after clearing it.