Hi guys,

Sorry for the dumb question, but I have a hard start issue with my truck at temps under 15C. It will idle rough and smoke when it misfires, but once I start to drive the truck for 30 seconds or so, it will totally smooth out and no smoke.
I thought it would be a glow plug issue, but when I checked all four with test light to positive bat and glow plug tip, they light came on, meaning the glow plugs weren't burned out. Resistance was at 0.4 OHM all four.
Hence my question, do glow plugs work but loose their efficiency to produce heat?
Any info would be greatly appreciated!!
Thanks in advance!

Ken