subaru_dadeo

Thanks for the responses. I discovered in an old Readers Digest car repair book that the red color can come from manganese additives in unleaded fuel. Regarding the knock sensor, we changed that yesterday with a "white" wire model, as we've heard the same story about the older knock sensors. Timing at idle is at 19 deg BTC now which is within spec.

My daughter pulled two one-month-old spark plugs from her '92 Legacy sport sedan, and the tip and ground electrodes were rust red. Coating doesn't rub off. I've never seen this before. Any ideas why this has happened? Plugs are Bosch Plus 4's. Engine idles fine, but she's noted some loss of performance. Also, I put a timing light on the engine, and the timing was about 29 degrees BTC. She thinks the knock sensor is bad & has another coming tomorrow. Could this be the cause of the (1) spark plug color, (2) performance loss, and (3) really advanced timing? Thanks!