PCV

hello. I don't know how often this happens but if you come across PCV problems with fuel trims related issues can you upload them? Thanks.

There's been a couple times I've seen PCV systems cause trim issues, I can go dig up the scan data on my other computer. They were on newer GM 1.4 and 1.8L Ecotec engines with ruptured PCV diaphragms and stuck return valves. Basically, the PCV system fails and puts 20" inHg vacuum on the crankcase. It results in very lean fuel trims and idle problems.

I've also seen a couple vehicles with stuck open PCV valves that produced no fuel trim changes. These were on speed density systems, and the stuck open valve just resulted in lower manifold vacuum, a high idle and IAC codes.