Help engine runs bad
 

my 93 civic dx D15B7 is running bad when left at idle for a long period, and smokes white, but it will not run bad on a cold start and no white smoke. i first thouggt this to be a head gasket but it only smokes after 20 min of warm idle. suggestions please

Any CELs? Any loss of coolant? Any oil mixing with coolant and vice versa? Any overheating? Have you done a compression check?

no milky oil or coolant

pulled out plugs

white smoke usually means coolant if i recall correctly, so it has to be getting into the cylinder somehow.

that said, the second pic looks really lean but could be the flash, and the fourth pic looks a bit lean on the very tip, is all I see there.

Sounds like a blown head gasket to me.

I was having the exact same problem with my 88 DX D15, white smoke was pouring out of the exhaust like crazy and idled like crap. Problem was my head gasket, it was letting water pour in on the left side of the block into a spark plug.

My friend who is a mechanic said my gasket and head are fine, it is the cts causing the ecu to not deliver fuel properly, as per the white smoke, no ideas but pressure tests passed.

Did your friend have any evidence other than a 'pressure test' to say it was fine? What 'pressure' did they test? Cylinder compression? I've seen head gaskets blow and not affect compression enough to cause running issues, but will still pour coolant into one (or more) cylinder(s) like a faucet.

White smoke = coolant
Blue smoke = oil
Black smoke = fuel

/story. I agree with Ron. Sounds like a blown HG