Excessive cap/rotor wear on S13; timing; failed emissions.

[slipnfall]

1992 240sx KA24DE engine cap rotor wear

Hi Folks, I am consistently getting signs of arcing inside my distributor cap. I guess wear isn't the right term, because the contacts themselves aren't actually abnormally wearing. They were replaced about two months ago, with OEM units. The auto-store brand 'wore' the same way. There are about 1/2" white marks after each post in the cap. Is this a sign that my timing is being advanced too far? I have my timing set at 20-21*. I timed it by pulling the TPS *and* using the consult tool. I should note that I got inconsistent idle results between those two methods at first.

The main reason this bothers me is this: I have been working on a buddies '93 240sx, on an unrelated problem. He has had an OEM cap/rotor on for well over a year. There are *no* white arc markings in his cap at all. Could this be a small vac leak causing the ECM to muck with the timing? FWIW, my vac at idle is roughly 19-20"hg.

Also I just failed my emissions test, with a new magnaflow cat. O2 was replaced in March '05 with an OEM unit(although the engine was broke in durring that period, so I suspect it may be oil-fowled). I always run 91 octane. I failed the idle test, *not* the high idle test. Over the limit on Carbon Monoxide and Hydrocarbons. Sorry I don't have the exact numbers at my disposal, but will try to get them this weekend.

Thanks for reading.Jamie

PS - I havn't seen much of NISTECH lately. Hope everything is ok.

[Silvia2NR]

Well, obvious advice I would give you is to check your oxygen sensor. Perhaps swap out sensors with your friends and see if you pass.

[slipnfall]

I just picked up an O2 sensor today. I was suprised to find that the local auto part store brand sensors were the same as the OEM units, at 1/2 price. Hey if Nissan uses Bosch sensors, then I'll buy Bosch. I'll post back tonight.

[slipnfall]

Here are the emission results w/a new O2 sensor:

High Speed 2379rpmHC: 94 (limit = 180)CO: 0.42 (limit=1.20)CO2: 14.3O2: 0.68

Low Speed 819rpmHC: 296 (limit=180)CO: 2.34 (limit=1.2)CO2: 13.1O2: 0.47

[slipnfall]

bump for some help - I know there are some emission guru's out ther!

[vancouverbc]

unplug the o2 sensor and measure the dc voltage . one probe on ground and one probe on the lead coming from o2 sensor. do this after the car is fully warmed up. if you get something like .9 volts your are rich.

check your codes in computer. there are a zillion things that cause a rich condition.