A friend of mine just put a 1.6 sohc from a 99 dx hatch into a 96 hatch. and the idle is not stable it starts from 1.5 then jumps to 2. when he starts the car the car is fine when it heats up thats when it starts the unstable idle and i can smell antifreeze after that but the temp of the car is right in the middle not overheating..


Any ideas?

 

This should help
https://honda-tech.com/zerothread?id=2019247

 

thanks also when unplug the map sensor the surging stops

 

so did u fix it yet? im having the same problem

 

Try cleaning the IACV. This has coolant running through it and can alter your idle to an extent. There also may be a leak in the hoses connecting to it and when the car warms up, it could leak onto the hot intake manifold causing the coolant to burn off... which would be why your smelling it. This is just an idea however.