91 DOHC KA Failed Smog High HC

[jesse5150]

So i went to smog my car today, its a 91 KA24DE with about 120,00 miles. I recently changed my oil, oil filter, air filter and PCV valve but i still Failed at idle with too high of HC and timing was 30 BTDC. What should i set my timing at to help pass and what can i do about having to high of hydrocarbons??

[yarou]

stock timing is 20 btdc

[jesse5150]

do you think being off by 10 could make me run so rich i would fail by around 100 in the HC's?

[Pacman]

When doing timing, have the engine fully warmed up, turn off, unplug your TPS, restart and set to 20BTDC. Timing could be causing that but with numbers that low, your cat may be getting slow at converting.

[joshy240sxxx]

new o2 senser as well that helped me

[jesse5150]

Ok, i fixed my timing and i'll hit up autozone tommorow for the O2 sensor. My brother gave me an extra cat he put on his civic to smog and took right off after passing, so my next question is where could i put and extra cat? I was thinking maybe cuting off the pre muffler (idk if thats what its called) but do i need that and how far back can i put a cat??

[Pacman]

Adding another cat will make you fail visual emissions. Believe it or not. The car doesn't call for two cats, just one. It'd be considered tampering. Things like the coolant temp sensor can cause it to run rich by tricking the ECU to think its too cold (not allowing closed-loop operation). Leaking injector o-rings, fouled plugs (or other secondary ignition componets), O2 sensors, exhuast leaks (pre O2 sensor) among others. Pull codes to check for faulty sensors, then test if not finding (or finding) things. Please, as someone money savey and as a tech, don't just throw parts at it. How far are you off?

[jesse5150]

So if i cut of the stock cat and weld on the other one i'd be ok visually right? because i could probably still cover it with the heat sheild... and i failed timing @ 30 BTDC and my HC measured @ 260 with the limit being 120 but only at idle

[Pacman]

You can remove the one and replace it, yes, but remember that 240's use 3-way catalytic converters. I don't know what Honda uses. Check the CTS and the replace the O2. Won't hurt and S13 O2 and CTSs are cheap.