kj217

a friend's 996TT is throwing check engine light constantly,, dealer says irs gas issue,,
i checked codes,, please see attached,,
car also idles at 1100 rpm,,
please help me figure out,,

GermanCarSpecialists

Can not see an attachment.

kj217

quota exceeded,,

kj217

there is also a weird humming/whining sound in engine bay,,

neanicu

Are you sure it's a humming noise and not a hissing noise? Maybe the car has a vacuum leak and that's why it's misfiring...
I would remove the serpentine belt and run it very briefly to see if the noise goes away. That would eliminate anything belt driven.

kj217

it misfires in one side of the engine,, weird?

kj217

car aproaches 1.0 bar of boost,, this eliminates vacuum leak i guess,,

Macster

"gas" issue? As in bad gas? Or a fuel supply problem as in too much or too little fuel?

Reads like a vacuum leak. The fact the engine develops boost doesn't eliminate a vacuum leak.

"02996ttx50

+1 on still possible leak in spite of boost

also, increased idle fluctuations along with abs/psm cels often indicate failing maf. though less so actual "misfires". coils crack also

wross996tt

P0507
32 Idle air control at stop - above limit

Possible fault cause
♦ Throttle is jammed
♦ Leaks in intake air system

So as already pointed out...there is a leak somewhere...

When was the last time you did plugs and coil packs?
Does the whining go away when you step on the clutch?

GermanCarSpecialists

You have a pretty decent vacuum leak in the car.

kj217

but why only misfires on one bank?

Macster

The leak is confined to a hose or fitting of one bank or the leak is off to one side and one bank wins the tug of war and gets the extra unmetered air. The other bank could misfire eventually but the car doesn't get used normally and doesn't get run enough for the other bank to misfire.

What are the fuel trims doing at idle?

Less likely is the MAF is acting up. I know of one case in a NA 996 the engine was misfiring on one bank and the cause was a bad MAF. Rare, but it is has be considered, if an intake system integrity test doesn't turn up any leaks.