2018 Chevrolet Silverado - P050D Cold Start Rough Idle

Question

Every morning when I start my truck, it idles very rough for about 20 to 30 seconds and then smooths out like nothing is wrong. It threw a P050D code which is 'Cold Start Rough Idle'.

I’ve tried running high octane fuel and some injector cleaner, but it hasn't helped. There is no coolant loss and the oil looks clean, so I don't think it's a head gasket. Once the high idle drops down, the truck runs perfectly all day.

FreightlinerFred · Accepted Answer

✅ Confirmed fix: This is almost always a leaking fuel injector on the direct injection GDI systems. One or more injectors leak a bit of fuel into the cylinder overnight. Upon startup, that cylinder is too rich, causing the stumble. Replaced all 8 injectors (per GM recommendation when several show high balance rates) and the cold start is now buttery smooth.

BigRigBenny · Answer

Check your intake manifold bolts. On the L83 engines, they can sometimes work loose or the gaskets can shrink slightly, causing a vacuum leak that seals up once the plastic manifold and gaskets heat up and expand. Try torquing them to spec when the engine is stone cold.

2018 Chevrolet Silverado - P050D Cold Start Rough Idle

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