Hi, I'm new. I have an 89 civic that I've started having some misfire issues with. It basically started when the ECU threw a water temperature sensor code. I reset the ECU and the code hasn't come back for about 600 miles, but it started misfiring. It will only misfire once it's completely warmed up, and it will only misfire at low throttle positions (maybe 10%) and it's worse when accelerating. Sometimes the idle is pretty rough too. I cleaned out the IACV (EACV) but it didn't seem to solve the problem. I've also put in a can of Sea-Foam, but it hasn't really fixed it either.

Please help, I'm driving to Nevada next week (2000 miles) and I want the car to make it.

 

Could be a few things:
[ul][*]Spark plugs need changing[*]You need new plug wires[*]Vacuum Sucks- not literally[*]Timing is off[*]Bad compression
[/ul]

 

I didn't think of it until just now, but we had the valve cover off just before the car started having issues. Is there a potential for a vac. leak through the valve cover? I know on my other car (1984 CJ7) the valve covers don't have much to do with manifold vac., but not sure on the B15.

 

Breather hose. The only thing that is related to vaccum. But I don't think it would be a problem. You might accidentally damaged/disconnected something else. Worth checking for loose plugs/hoses around the engine I think.

 

I decided to buy a new coolant temperature sensor for $30. I'll put it in tomorrow and see how it goes.