Definitely car running rich - but you need to advise how the car actually runs in order to pinpoint the circuit that is giving you the problem - what is your warm idle - does the car warm up - does the car bog or hesitate - is your timing correct - are your spark plugs gapped to .028" - is your check engine light on with the key on and off when running, and can you get a code 12 from it?? Etc.
Sorry for the lack of info. It started with a wandering warm idle. Clutch in at a stop light idle stays at 1500-1800 for 5-10 seconds then slowly drops back to 850, then down to 500 rough idle then recovers to 850. thought it was IAC. It's also using a little antifreeze and now I suspect the EGR has internal corrosion and is leaking antifreeze into the EGR flow. Pretty much ruled out head gasket for A/F usage. It's always seemed to run rich. Injectors? Last tankful was 35 MPG imperial and it's always seemed to run quite well. '97 1.6 16v Doug Thorley header, no cat. Thanks all for the help. I'll keep plugging away til I get it! Cheers, Dave
You should start with a compression test (all plugs out, F1 fuse removed, well charged battery, gas pedal floored when cranking) to confirm your engine timing. Make sure plugs are gapped to .028" (.07mm). I don't believe any coolant runs through the EGR system, actually. And regarding drop in coolant, I would first confirm no pin hole leaks etc. in the myriad of 20 year old hoses on the car.
Confirm the operation of the check engine light, as well.
However, 35 mpg imperial, converts to 29mph US, which seems to negate 'running rich', as this is pretty perfect gas mileage.
OK. Here's what I think was causing the black soot; I suspect that the antifreeze it is burning is coming from a crack around one of the intake valve seats. I say this because the fellow at the machine shop said that 16v engines are prone to cracking there. I overheated it really badly a couple years ago and eventually the head gasket went. I had the head surfaced, but I don't know if the guy (different from the one who told me about the cracking) checked for cracks. I tested for HC in the rad and there was none, but always a little smell of antifreeze in the exhaust. I also plugged two cat cons and was told antifreeze is dynamite on cat cons. And I'm losing antifreeze and there's no leaks. Soooo, I cleaned the plenum, throttle body, EGR, IAC etc. and put it all back together but with the EGR blocked off. And that's how it will stay! Seems to run fine. Now I think I'll have a beer and watch some soccer!
That's what I originally thought but there's no disturbance in the cooling system, (pressure, bubbles, contaminants) I'm not saying it's the cracked valve seat is the source, but it's coming from somewhere.