Mass air flow sensor trouble
 

ok to give some background on this. My engine has been running rough when idleing. it is really shaky and the rpms are at about 500 it varies. I have replaced o2 sensors, idle air control, tps, and mass air flow sensor. a buddy of mine works at local parts store looked at it and told me the mass air flow was bad so i unplugged it and engine leveled off and ran great at idle. it was idleing at about 12 13 hundred rpms. still not good that was to high so i put a new mass air flow back on it and as soon as i go the new one on it still doing it anyone have a clue what is makeing the mass air flow sensor read wrong. the codes my computer give me are bank 1 and 2 are lean.

Re: Mass air flow sensor trouble
 

Where on the fuel map are you running lean? Your fuel trims are likely postive % indicating that fuel is being added to the factory calibration at some level of load. If the trims are positive under low or no load (idle) that the likely solution is that you have a vacuum leak. Under high load (for example, highway driving) your throttle plate is open, which is a vacuum leak by itself. A minor vacuum leak will not contribute to increasing the fuel trims at high load because the throttle plate itself is open. You will see the fuel trims level off at this high load. You can observe that with a live data scanner. I suggest checking your fuel trims, and checking for a vacuum leak with a nice stethescope.

Re: Mass air flow sensor trouble
 

well in reality it's not running lean it's running way to rich that is why it's idleing rough and blowing raw gas out you can smell it i was going to replace the intake air temp sensor next cause i was told that it helped control the same as mass air flow sensor. I am really lost and when it comes to vacum leaks i am even more lost i have checked those about thirty times cause that is what i kept thinking