Need some help sourcing a problem with a W reg new beetle. Car drives, but misfires and drives "lumpy".
Scanned with vagcom and these came up
6 Faults Found:
17536 - Fuel Trim: Bank 1 (Mult): System too Lean
P1128 - 35-00 - -
16556 - Fuel Trim: System Too Rich: Bank 1
P0172 - 35-00 - -
16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 35-00 - -
16687 - Cylinder 3 Misfire Detected
P0303 - 35-00 - -
16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 35-10 - - - Intermittent
16687 - Cylinder 3 Misfire Detected
P0303 - 35-10 - - - Intermittent
According to rosstechwiki
17536/P1128/004392 - Fuel Trim; Bank 1 (Mult): System too Lean
Possible Symptoms
Malfunction Indicator Light (MIL) active
Possible Causes
Mass Air Flow (MAF) Sensor faulty
Oxygen Sensor Control faulty
Oxygen Sensor(s) faulty
Fuel Injector(s) faulty
Possible Solutions
Check Mass Air Flow (MAF) Sensor
Check Oxygen Sensor Control
Check Oxygen Sensor(s)
Check Fuel Injector(s)
16556/P0172 - System Too Rich, Bank 1
Possible Symptoms
Irregular behaviour
Possible Causes
Fuel system
Excessive fuel pressure
Leaking or contaminated fuel injectors
Leaking fuel pressure regulator
Low fuel pressure or running out of fuel
Vapor recovery system
Air leaks after the MAF
Vacuum leaks
Improper seated engine oil dipstick
Stuck EGR valve
Oil overfill
Cam timing
Cylinder compression
Exhaust leaks before or near HO2Ss.
Any ideas? How do I check MAF, O2 sensor and injectors separately? I did had a quick look under the bonnet and found and fixed a big old vacuum leak behind the intake manifold, it was a hard plastic pipe which I managed to repair and it's not leaking anymore, car does run smoother but still misfires.