So I have a '99 ford escort 2.0 SOHC engine that I just rebuilt the head on (pre-valve seat drop). When I did that I also changed the timing belt, serpentine belt, thermostat, cleaned the intake manifold, have new spark plugs, wires, radiator fluid, transmission fluid, PCV valve, and IAC valve. I also replaced a couple of vacuum tubes that were bad. HOWEVER, I’m still having a odd issue with this car!
I figure I’ve got some sort of sensor or fuel related issue, but here’s a brief description of what I’ve noticed. The car starts and runs with throttle just fine. Sounds good, everything seems ok (except for the thermostat which isn’t seated properly causing the car to run basically cold, but it will be fixed within a day), but when at idle I get random misses or ‘catches’? Basically once the car has been running for a few minutes and i stop at a light that I have to wait for, the car will idle fine, then slow a tad (barely noticeable), ‘catch/lurch/miss?’ and then run fine again briefly and repeat. The frequency of this is not consistent and it happens at random, but increases with engine load. If I have the headlights on and the A/C (defrost) on it happens more often, but again, always during idle only. When sitting parked, in park and the headlights off, it almost never does it.
Anyone have any suggestions? I will attempt to run a fuel pressure test tonight to see if there is anything on that end, I have no check engine light or codes currently so i’m kinda at a loss. Should I try to reinstall my old IAC valve? Does this sound like some sort of other ‘common’ symptom? Injectors? It’s frustrating tracking this thing down, but again, any input/tips you could give me would be useful.