Rep Power: 0

I have a 98 EX 1.6 vtech. It had a blown head gasket. I replaced head gasket, rebuilt the heads and valves. Ran great for a few days but now it drives sluggish when engine is cold and shakes a bit. It will occassionaly stall when idle to a stop. **Timing light shows in perfect time. It starts immediately. I have checked every hose for vacuum leak and there are none to be foundd. I pulled the IACV and cleaned, no problems there. It does not idle up and down, it is just sluggish and hesistant until warm.

 
Rep Power: 189

Did you replace the cap, rotor, plug wires and plugs as well as fuel filter when you did your head rebuild? also make sure that the battery terminals are tight and clean, same for the engine ground and in the engine bay fuse panel the 2 Philips head screws that hold the battery wires down are tight.

 
Rep Power: 0

Yes. All New.

 
Rep Power: 189

hmmm run some fuel injection cleaner through the system then, also it is possible that it could be a intake manifold vac leak warming up could seal it up tight. Where does the idle sit when cold at first start and when warm.

 
Rep Power: 0

Idle at cold is around 500 and the same when warm. However when it's cold and you go to accelerate it's just a dog with no power. While coasting to a stop (not in gear, foot on or off the clutch, not on accelerator) rpm's will drop and die. Again, once at operating temp it will take off as quick as you could expect a little 4 banger to do and it will run like a top.

 
Rep Power: 189

idle should be around 600-700 at idle when warm, when cold it should be around 1200-1300. it sounds like you have a faulty coolant temp sensor, its a 2 wire sensor around the thermostat area, however it should not be stalling out on you unless the iac valve is not functioning properly.

 
Rep Power: 0

I have watched the coolant temperature with two different diagnostic machines. It operates properly.

Wanted to ask a question. I read in a post somewhere that the FITV (Fast Idle Thermo Valve) controls idle until the engine reaches normal operating temp, at which point the IACV takes over. In this case the FITV is built onto the throttle body and cant be serviced without drilling out brad rivets. I talked to Honda Parts and they said the entire throttle body has to be replaced in order to replace the FITV. So, the question is, is this something that could be caused the by FITV?

 
Rep Power: 189

the idle air control valve is what controls idle when both hot and cold, the ecm tells it to open/close the port via a linear actuator in that valve. I would go back to basics and check/clean and lube that iacv again, also replace the gasket while your at it, a small vac leak can make a big difference at cold temps for idle. Just because you see it on the diagnostic machine does not mean it is in specs for where it should be, it could be reading low or high, unless you are using an infrared thermometer to tell what the real temp is I would not trust it.