92 VX failed smog too high HC
 

Anyone have readings from their o2 sensors? Either stock or otherwise?

I used this post to get my readings:
https://www.gassavers.org/showthread.php?t=2427

This is with the CA ECU on it.
(edit: went back and did my readings again, got a bigger differential)
During warm up it's random between -1.9 and 1.0
At idle it's at 0.3
Under light accel -0.5
Under heavy accel -1.9
Decel it goes to 1.9 then quickly back to about 0.3

I get a CEL of 48 for the LAF sometimes. I also failed emissions due to high HC. Actual around 180-220 when allowed is 140.

The code says I need an o2 sensor, but my readings show a good differential which means it's probably working right? Smog guy said it needs a cat, but that wouldn't effect HC much right?

I've done the usual oil, plugs, cap rotor, filter already. Ran some seafoam through the tank, intake, and oil and changed oil again, haven't retested yet though.

Cat CAN help HC. one test of a cat is O2 storage capacity, reason being it's supposed to store O2 to oxidize the unburnt HC. unfortunately I only know how to test it with an oscilloscope.

*disclaimer: the following may or may not work for you. it can fry your cat or cause other damage up to and including death and considerable destruction*
start the car, warm it up: drive around the block a few times. get the engine warm and the cat warm. stop, open the hood, hold the throttle open to rev the engine to 3k and pull a plug wire (best with individual coils cause you can pull the primary wiring to less than all the cylinders) the idea being to dump unburnt fuel and air down the exhaust (see where the death/destruction/burnt up cat can happen?) to get the cat really hot to burn off any deposits like carbon from internal oil leaks. you want to do this for 5-10 seconds. too little and it won't help, too much and bye bye cat.

usually if you get a code for a sensor being bad and the sensor itself tests A-OK, it's a wiring issue between the sensor and computer. the other possibility is that something else is the problem, resulting in the engine running badly, which is picked up by the computer on said sensor but the computer doesn't know the difference so it says the sensor is bad.

how are the injectors? This seems like a really overlooked item that while expensive to replace, can use a good cleaning and or rebuilding of.

I've read about the burning stuff off the cat idea.
I might give it a try. Also it looks like adding some denatured alcohol to the gas tank can help lower hc as well. My registration is due, so at this point the car is worthless unless I can get it to pass. The engine has 260k on it, so if it explodes from trying something on it, it was going to die soon anyways.

Having the injectors cleaned is something I've been wanting to do. Just don't have the cash, it's already costing me hundreds to try and get it to pass emissions so I can register it. It drives perfectly fine, so this is all just to pay my taxes to california. It seriously makes me want to move out of state.

I ran seafoam in through the vacuum line which should help the injectors.

Current plan is try it tomorrow after the seafoam and fresh oil, then try the denatured alcohol, then a cat.

Had one guy that hooked it up manually and told me it wouldn't make it, and didn't charge. Went back but the boss says $35 for a pre-test, each time I do it. Won't even let me pay, hook it up, test it, let me change the timing in place to see the effect, and test again. I would have to pay, unhook and take it home to adjust, then pay them again or pay them $120 to set the timing on it. Guy said 'the boss is kind of an *******' and gave me some other places to try.

Tried another place and they wanted over $50 to do a pre-test. I asked for just the tail pipe test without all the checking timing, pcv, gas cap, etc, and they wouldn't do it. "got to keep the guys busy with work" Well, I offered you -some- work for them. Guess he expected me to just agree and pay it even though I didn't need all of it. I bet his 2 guys he had working there probably spent the rest of the day sitting in their chairs in the waiting room without any work at all. He was just generally an *******, if he hadn't of been he would have got my business if I end up needing a cat since they are also a muffler shop.

I had the timing retarded a bit and that may be why it had the LAF code. Reset it and so far it's not back yet.

Also I've pulled out the o2 sensor and can see into the cat, it's grey brown colored and isn't obviously damaged or covered in a ton of crap.

Pass, but barely.

750 rpm
co2 10.7
o2 5.7
hc max 120 meas 101
co max 1.00 meas 0.03

2450 rpm
co2 14.2
o2 0.5
hc max 140 meas 137
co max 1.00 meas 0.19

I know you got it to pass, but take a look at all your vacuum lines to make sure none of them have come off their connection or are cracked. My '88 Escort maxed out the emissions testing machine on tail pipe test in NC once and all it was was a leaking vacuum line.

A pass is a pass....

Good going, happy for you. One thing, you can see into your cat? Unless you're using some kind of optical or video equipment I don't think you're looking into your "cat". Perhaps your exhaust manifold? How likely is catalytic damage when running w/o an O2 sensor? (uh, yeah, guilty as charged)

He won't be so lucky next time.. Also failing a smog is a great way to hurt resale value of a car and if it fails again, it means the car wasn't properly fixed in the first place which is a trend in of itself. Also you don't want a high HC output because that means you're wasting fuel which hurts your fuel economy.