Hello, I have recently bought a 2012 523i with 3.0 n53 engine , 170.000 kms.
The Car already gave me lots of problems , but I am determined to fix It.
It has Always run Rich with sooty exhaust , High fuel consumption 6-9 km/l mixed Urban and highway with some light towing .
I noticed a very lumpy idle at Cold starts only , found wet plugs and verified that 3 injectors were leaking , so I replaced them and coded .
Also 6 new Spark plugs and coils .
This fixed the idle , checking operational smoothness at Cold start with Ista d returns values around zero for Every cylinder ( between 1 and -1 ) , so I Guess the injectors are now fine .
But I still have High fuel consumption , although a bit Better , managed 11 km/l on a tank of highway diving , but still around 6 km/l in Urban and towing a very light motorbike trailer.
Still sooty exhaust .
I keep getting errors for nox sensor , trying to find the courage to buy a 500 euros genuine sensor , because I fear the errors would persist or the fuel consumption would not change.
I don't have any error regarding nox catalyst .
Has anyone installed a genuine nox sensor and gained normale fuel consumption ?
Don't tell me to buy Noxem , because I had a terribile experience with the Seller.
Lastly , I keep getting the error regarding the intake fuel differential pressure sensor , bought a new Non-genuine sensor from auto-doc (vemo brand) , installed , but the car seems to reject It because when I delete errors memory with ista It stays on permanently without being canceled . Instead , with the genuine sensor , The error disappears after ista deletes It , only to reappear after a short drive .
I tried the test Plan with ista for testing the sensor , and It seams to work as intended , but the error Always comes back ( the program says It occured millions of times !) Could It be a vacuum leak ? I couldn't find any when I recently disassembled the plenum for cleaning intake valves , EGR , throttle body... )
Any input Is very appreciated , as this car Is diving me nuts !!
(Not to talk about vibrations , brake judder , and suspension problem ...)
