Technical assistance is currently receiving calls after the engine has been disassembled with no trouble found before completing SI diagnostics for DTC P050D,
Please be sure to first follow SI diagnostics then, if DTC P050D flow chart does not isolate the concern, the following may be helpful
Code P050D DescriptionDuring a cold start, the engine control module (ECM) commands dual-pulse mode during Open Loop operation to improve cold start emissions. In dual-pulse mode, the fuel injectors are energized twice during each injection event. As with misfire diagnosis, in dual-pulse mode the ECM monitors the crankshaft position sensor and the camshaft position sensor to calculate crankshaft rotation speed.
In normal operation, optimum fuel delivery during dual-pulse mode produces a steady crankshaft rotation speed. If the variations of crankshaft rotation speed exceed a calibrated value, the code P050D will be set.
Misfires on start up only, with high rates always on one cylinder, can be suspect for coolant entry at the liner to deck face casting or the casting line in the intake port of the cylinder head.
To inspect for this concern, add coolant dye to the system, run engine through warm up, pressurize the cooling system after warming the engine to operating temperature (let the engine cool overnight) and inspect the suspect cylinder with a borescope for coolant dye evidence.
At times it may be necessary to remove the head for inspection.
If the head casting line is the concern the intake port will be wet with a coolant oil mix.
This could be the cause of a running rough warn concern with or without codes.
The location of where the coolant is running down in the port will also look washed down.
If this is found the cylinder head will need to be replaced.
For coolant entry at the liner to deck face casting of the cylinder bore.
It is hard to see the actual source (pin hole) but it usually streams down the liner so that you can see it with a borescope.(Sometimes) The top of the piston will be steam cleaned.
Do not confuse residual fuel on the piston crown / surface as coolant. Some fuel residue may be present and can be mistaken as coolant (reason for the cooling system Dye to be added). Use black light to confirm the liquid is coolant. If this concern is present, do not replace the cylinder head because that will not repair this concern. Call PQC per the latest version of 16-NA-338, if required, reference this PI and replace the engine.
Small surface pock marks or pitting appearance on the deck surface is normal and engines should not be replaced for such appearance as they do not connect to coolant passages and cause a leak path that generate engine misfires. During engine warranty analysis studies, engines are being replaced for small pitting in the deck face as described above, when the subject cylinder / piston is saturated with fuel and not coolant
Engines replaced for light / shallow pitting conditions will be returned to the dealership as non-defective.