ok i just bought a 93 civic lx from a guy because he thought the head gasket was blown, im almost positive its not. it runs very smooth when in gear but is creating alot of white smoke and the idle when warm is very weak and sometime cuts out on me. also uses as much fuel as a V8 right now. my friends camry had the same problem and she said a mechanic replaced her egr valve to fix it. im fairly experienced but i have no idea what and egr valve is or if this should fix my problem. please help, i need to get this car running properly within the next month!! also i have alot of records for repairs and maintenece on the vehicle and its been very well taken care of.

 

Unless it's a California car, there will be no EGR valve on that model.

Does the white smoke smell like antifreeze? Does the coolant go away? If it's not the head gasket (head gasket denial can run deep), it could be a leak from one of the parts on the intake manifold that has a coolant circuit. That won't affect gas mileage though. How sure are you that the mpg is low? Don't count on the gauge to read proportionally.

You could also idle for a while then stop let it cool off and take the spark plugs out to inspect. If one or two of them are wet and / or super clean it's almost certainly a head gasket leak into those cylinders.

 

i think the gas mileage is down cause i bought the car only an hour away and it killed more than a quarter tank, then again it is only an 11 gallon tank. the oil and coolant are definitely not being mixed, the radiator was just replaced less than a year ago and the fluid is still prestine, the oil is very black but not milky. and i did pull all the plugs (which were dry and still looked ok) cause i had to drain the first plug chamber of oil cause whoever did the plugs in april for the guy dropped the plug chamber/valve cover o-ring IN the valve cover. luckily it wasnt torn up, but do you think that could have caused damage and created the current issue?

 

Were the plug real clean? White smoke is water or antifreeze. All it takes is a few drops every stroke. Just because you do not have water in the oil or oil in the water means nothing. A bad head gasket between the water port & combustion chamber will cause white smoke. I'm betting a head gasket or broke or warped head.