Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
I have 2015 chevy cruze lt 1.4 eco boost engine. When i start the vehicle it turns over with a nasty rough start. Once running at idle, idle is really rough. But once im driving vehicle runs fine. And once its heated up rough idle tends to go away. Also as im slowing down at low speeds less than 20-30 mph, the engine RPM spikes up briefly. Causing the weight of the car to drag car weight forward is how i would describe it. I want to believe it could be carbon build up on exhaust valves. I wanted to hear feedback from others tho on this. My PCV is functional as well
The Eco Boost have a known issue with the pcv system built into the camshaft/valve cover and a valve in the intake manifold. Do a google search, but on the drivers side of the valve cover is a diaphragm on the camshaft cover that goes bad due to the sticking valve of in the intake manifold. The diaphragm is not serviceable but the camshaft cover is.
Many articles on how to quickly determine if the diaphragm is bad, but if is, then the valve in the intake manifold is also bad. There are work arounds to fixing this permanently without removing the intake manifold. Replacing the cam shaft / valve cover is very easy. Be careful coil connector breaks easy.
