[zman]

I've seen a few other threads and attempted to diagnose the fault but to no avail, so until i can get my car to my mechanic next week, perhaps you guys could help!

Symptoms
- idles rough. Upon start up it'll idle normally but as soon as i touch the throttle or turn on the AC, the idle will sounds like a WRX
- its down on power, i'd estimate its down roughly 25%. maybe more.
- i've removed all 4 plugs, all covered in dry black soot. The plug closest to the radiator was the blackest. whereas the last 3 plugs were black, but the tips were greyish.
pic of plug no 1 https://imgur.com/a/9wVMc
- theres definitely an odd smell. running rich i guess.
- no CEL warning

so far i've tried:
cleaning the ICAV unit, no change
cleaning the MAP sensor, no change
replacing the spark plugs, no change
i've lifted the coilpacks individually. each time the car's idle would dip so i'm guessing they're all working ok?
i've put my ear against a screw driver which was placed against each injector. all 4 seem to click consistently.
the first (upstream?) o2 sensor is covered in dry black soot.
the rear o2 sensor is light greyish.
Australian spec so no OBD2 port.
new tank of fuel

have not done a valve adjustment, but i'm assuming the problem would not come on so sudden?

have not done a leakdown test or compression test yet.

the other thing is the car was not driven for 5 months but i've driven it for 2 weeks since then. All was well, plenty of power, until one morning it just started to play up.

Any ideas?

windhund116

You aren't getting any CEL errors? Or if no OBD-II = no CEL light?

What is the oil consumption? Looks like an O2 sensor issue. ( WAG).

s2000Junky

The plug looks oil fouled to me.

How many miles on this engine?

Is it an F20 or f22?

Oil consumption rate?

Id probably start thinking about a comp and leak down test.

windhund116

BTW... what spark plug heat range did you put into the car? Maybe, too cold?

Thanks.

[zman]

Nah no engine check light comes on at all.
My 1999 model doesnt have the OBD2 port from what i've read.

F20, 247,000 km!
yeah i'll do one soon.
although the issue came on very suddenly so i'm guessing its probably electrical?



BKR7E-11
similar specs to the platinum ones i took out but made no improvement.

s2000Junky

The comp and leak down test is definitely worth doing, certainly with the mileage on your motor, but if you have a friend in the club that is so willing, id be curious to see if your problem goes away by simply swapping in good known coil packs. Its possible they could be tired, enough to combust under low fuel demands such as idle, but under load spark is weak and wants to poop out. Its a theory based on your list and symptom, so definitely worth trying if you can get your hands on a set.

[zman]

turns out it was faulty ignition coil #1
So moral of the story is, test your coils by disconnecting the plug, instead of lifting the coil off the spark plug

Slowcrash_101

If you only replaced one ignition coil, be prepared for the rest to go out.