After replace MAF sensor and throttle body, my car 07 XC70 ran good, smooth, accelerate strongly, but the check engine light still on with message "Engine system need service" OBD II scan said fuel system run rich, and MAF or VAF sensors probelem; Can some one tell me what is the VAF sensor and where it's locate? Thanks

 

The actual code would help.

 

The codes are: P0101- MAF or VAF, P2188 -Fuel system too rich at idle speed; I don't know if these two codes are related? And what is VAF and where it's located? Since air fuel mixture was controled by ECU, what make the engine ran too rich atthe idle speed? I apreciated any help.

 

I've dealt with a similar issue on a 2006 Volvo S60 2.5T. I was getting a lot of correction at the fuel trim because the air mass meter was bad. Basically, the oxygen sensor will true up the fuel being sent by a reference signal from the mass air flow.

You have to have a scan tool that can record a graph of the fuel trims.

 

How do you do the fuel trim? I thought air fuel mixture were control by the ECU? I suspected the turbo is not kick in at idle that's not blow enough air in the engine at idle, but I don't know how to check if the turbo is work properly? Does the turbo need lubricate, if it does, how do you lube it? I apreciated any advise.