Keeps failing emissions

I took my 92 Olds through emissions earlier this week expecting a California car to pass emissions in CT, but it failed  

Here's the reading from my first test

Hydrocarbons (HC) Reading: 64ppm, limit is 53ppm
Carbon Monoxide (CO) Reading .20%, limit is .28%
Nitrogen Oxide (NOx) Reading: 505ppm, limit is 614ppm

So I failed that test on the HC. The tech said it could be ignition related. I did a tune up on it which included cap, rotor, wires, plugs and O2 sensor. Everything was original with 169k on it except the cap and rotor. The plugs looked worn but ok. I gapped everything to .035 per the label on the rad support. Car runs good now, idles smoother. I threw a bottle of that guaranteed to pass stuff in the tank for the hell of it.
This car has always idled high since I bought it, about 900-1000 rpm in park and between 6-800 in drive. I checked for vac leaks, didn't find anything. Lynol, who has a 92 OCC as well said his is about the same and passed NJ emissions.

I took it back to emissions today to get it retested. I took it up on the highway for about 15 miles to get the cat good and hot then took it right to the test center and got right in without waiting. It comes back failed, this time much worse than before!

Hydrocarbons (HC) Reading: 82ppm, limit is 53ppm
Carbon Monoxide (CO) Reading .38%, limit is .28%
Nitrogen Oxide (NOx) Reading: 410ppm, limit is 614ppm

Anyone have any insight of what's going on here? One thing I'm noticing on the test forms is the engine temperature they recorded seems low. My first test was 168 degrees, but I was close to home when I went there. Today it was at 176 degrees after all that driving.

Even though you are passing, that NOx number is high. I would carefully check the EGR. I definitely think your thermostat is not closing all the way. Mine failed on my 92. It would stay open about 1/8". The correct stat for your 92 is 195.

I did the vac test on the EGR (push diaphragm in, cover vac port) and it seemed ok, but I guess cleaning it out can't hurt. So a slightly open T-stat can cause a fail? I guess I'll throw a new one in then, can't hurt.
A friend of mine mentioned a TBI rebuild might help with my idle issues, along with he says the connector for the IAC tend to fail intermittently. I think I'll pickup the kit and do that too, at this mileage it can probably use it.

Yes, slightly open stat makes it run cold, cold engine means higher emissions.

buy a new aftermarket catalytic converter,. it'll probably pass then.
My 93 tbi van was a dooosh to pass emissions,. bought a new cat , all was good.
YRMV
NWEOI
DSAOR
PDCC

Nick

I threw a new temp sensor in there today, got it good and hot and my scanner still shows about 180 degrees. Managed to borrow an IR thermometer and the housing is about 197, so I guess the CTS is a bit behind. I priced out the cat, it's a lot more affordable than I thought. Ill add that to the list, thanks guys.

Rebuilt the TBI and the car runs great now, idles normal and feels a bit more responsive. I have the new cat and a temp sensor, hopefully I can get that in this weekend.

Good luck with the emiision test,FINGERS CROSSED!

Replaced the CTS last night. It's a little better, shows about 185 with the engine hot on my scanner. The t-stat housing shows 195 with in IR thermometer, so the stat is good now.

Is that temp measurement idling with the car warmed up? Check it immediately after driving on the highway.

jayoldschool wrote:

Is that temp measurement idling with the car warmed up?  Check it immediately after driving on the highway.  

That's idling after some light local driving. Now that I finally got it registered I'll take it out for a long drive and see.

I can finally put this one to rest. I replaced the cat with a walker universal one which cost under $40 with coupons from advance   . The old one was a replacement that was literally half the size of my new one. Took some fighting to get the new one in there but its in and did the trick. I got 19ppm on the HC test. Other numbers were very low as well. I also drove in 2nd gear to the test center just to make sure all was running hot   . Thanks for the help guys, I can put this problem to rest now.

Good to hear you are finally legal,glad we still dont have it here but probably will very soon.

i just had some fun with the wifes fancy ford,. 4.6 motor,.sat for 16 months or so,.fixed the a/c, new battery,. then....
P0420 ,. so i dumped 1 gal of lacquer thinners and 1 gal of methyl hydrate into 1/2 tank full of fuel,.
i had to drive it long enough to achieve drive cycle on all systems so i thrashed that poor thing for a 200+ road trip,.no more cel,.

passed emissions,.

10 miles from the test station,. P0420 popped up again,.. haha,. F'em,. trst good for 2 years,.

cleared the code,. its got another 2-300 miles on it,. light still out,.

if i lived 3 miles north i would not have to worry about emissions tests,..aaaaargh!!!

Interesting thing I found about 96 (or at least in my caddy) is that the readiness monitors go green right after a clear. I'd been chasing an evap leak on that thing and though I got it, but as I pulled into the test station the damn light came back on! I said to hell with it and cleared the code in the parking lot, noticed my scan tool (phone) said all monitors were good so I handed over the keys. I was really surprised to be handed my passing paper work after that one.

On the other hand, my 01 Aurora took close to a week to get those monitors all green and ready to go. Took some 3rd gear driving to trick it into thinking the trans wasn't broken   .