Hello, I recently took my 92 rs 305 tbi to get inspected, and the results were pitiful. At 15 mph the hc was 244(standard is 117), co .67(standard .67), NOx 3236(standard 907). At 25 mph the hc is 244(117), co 1.59(.65), and NOx 2399(821). I've read some of the other emissions posts, and plan on replacing parts I've seen suggested, but where do I start? I had to cut the muffler out to replace the fuel pump and sending unit. I patched it back in with a flex pipe and clamps. My main concern is getting the NOx numbers down. The egr passages in the intake are clear and the engine almost dies if I manually open the egr valve. I've replaced some vacuum lines and the others look good. I don't want this anniversary present to go to waste.

 

Looks like you need a cat.

Try a cat and a cat-back exhaust system, since it sounds like your car needs that too.

 

Thanks for the reply. That is in the plans. I'm either looking at a full flowmaster or magnaflow setup.

 

Just a question/observation.

A 1992 model year is 21 years old.
Why is the state of TX forcing you test the car?

I believe the EPA regulation (which is federal law, not state) says after 20 years the car is exempt.

When they started emissions testing in IL in 1987, the cut off was 1967 and it has progressed from there.


If this is not a daily driver did you opt for the race car / show car waiver ?

I would try to clean up the emissions best you can if it is a mostly "stock engine"

 

That is a lot of HC.... but Before you assume it's the Cat convertor

Have you altered the car / emissions control systems is any way?

Have you checked to make sure the A.I.R. is functioning.. (pump... controller, etc)

Checked the timing?

checked the T-stat?


If you spend more the $700 in repairs and still do not pass you get an exemption, good until the next testing cycle. but the catch is if the car is 1981 or newer, the work has to be done my a certified shop.

SO if you work on the car yourself you cannot qualify for this sort exemption.

best long term plan is try to get the race car / show car waiver.

better yet is find out why your 21 year old car still needs to be tested.

 

Connecticut makes u pass till 25 yrs old or more. Believe a state can be tougher then federal law but minimum is 20 yrs federal.

 

that is probably the case...

I would try to get the race car / show car waiver


or tell them the car is not able to the be tested because it is out of service undergoing restoration.

Park it for a few years, by the next testing cycle it will be an antique.

If this is a daily driver then you don't have than option.

 

State laws can be more strict than Federal, just not less(California is a great example).
In Utah, our testing starts on '67 and later for a vehicle you want to register under standard guidelines.

 

In Texas it's 2-24 years old that require emissions. I didn't see anything about a waiver, but I'll look again. Besides the exhaust, something else is wrong, and I want to make it right. The car cranks, idles around 600-700, cruises, and picks up pretty good. Doesnt overheat, even in houston traffic on a 100* day. Ill have to get a vacuum tester though, because its good to have one. One good thing about the test is it'll let you know if something is wrong.

 

No alterations by the way. I just got it not too long ago, but it did sit for several months.

 

What did the PO do to it? don't assume it has not been altered..

Is the AIR system present and operational ?

with HCs that high something is screwed up, A vacuum leak would not throw the HCs up that high... but yes... test the lines.. especially the feed to the MAP sensor.

The cat converter could have been gutted, since you want to upgrade the exhaust that is easy to check..

If an emissions component was bad, has a vacuum leak or electrical short ( like the MAP sensor, O2, etc) you should have trouble codes. and check engine light should be on.

No codes means you have an issue with something else:

Cat converter
Valve lash
Ignition timing

check the basics... Did you do a basic tune up? plugs, wires, cap, rotor, air filter?

Also before you retest take the car for nice long drive to get the exhaust hot..

 

FRMULA88, in Texas the emissions sticker is also the safety inspection sticker which has to be done once every year here.

some of this has been said already.
saponi1, from the numbers you posted & age of the car, i would say the cat is at the very least weak, its running a little rich, and you have problems with the EGR system.
with everything else working ok, high NOx from a bad cat is seldom over about 1200 ppm or so.
at 25 mph the CO is high even if it did not have a cat.

things i would check are timing set to specs.
you can usually pull 1~2 degrees from the factory spec and normally get a small drop in HC & NOx and sometimes CO. i always saved pulling timing for last if a car was just outside the standards.

2, the EGR system operation. at over 2000 ppm i have no doubt the EGR system is not working.
too much timing advance could drive up NOx to very high levels, but the motor would "ping" badly and i would expect you to have a post about it.
the EGR solenoid must be plugged into the right port on the throttle body, an intake vacuum source will not work.

3, the O2 sensor can be working good enough that the computer won't set a code but still be bad.

4, the AIR injection system. its not unusual for one of the valves to start leaking air. if fresh air is injected into the manifolds when the system is in closed loop, the computer will think the motor is lean & add fuel which will raise CO & HC.

the motor needs to be at operating temp.
engine temp has a big influence on CO & to a lessor degree HC.
engine temp has little to do with high NOx unless it is getting into an overheat condition.

unless its changed from 3 years ago, the amount to get a waiver in Texas is $600.00 for emissions related repairs. if the work is done by a shop certified by Texas to do emissions repairs, then parts & labor are included. if done by a shop not certified or you do it yourself, then only the parts count toward the waiver. things such as ignition components, the cat, AIR system, air filter, oil change, computer system, injectors are all emissions related along with a few other things. there is a time limit on how long repairs were done & when the car was taken in.
there is also a low income waiver that can be used once if you make below a certain amount each year. unless they changed it since i was doing emissions repair, it doesn't matter who the car belongs to. your son could take your car in & qualify for the state to pay up the $600.00 as long as he is in the same household.

you can find the info about the waivers here, http://www.dps.texas.gov/rsd/vi/index.htm

 

Thanks for all the info. All the emission parts are in place. I haven't done any tune-up work yet. The plugs and wires still look pretty good. Last night going home from work, the check engine light came on, when I checked the codes, I got a 32(egr) & 53. I looked up the 53 & it said, charging system failure/egr solenoid. That and the o2 sensor will get replaced first. The guy I got it from has 2 chevelles and a 57 Chevy so he didn't mod this car. (Why bother?)

 

You can get a new cat on it but most likely your testing facility has a problem,, I found out the hardway that the dyno testing facilities when they get old will read too high on Hydrocarbons most places don't even do it anymore. I would just find a place that will pass it. I know I'm in Houston too.

For the rest of you guys the Houston area is almost as bad as LA on smog regulations. We got forced into a special agreement with the EPA

Also you can red tag it if the repairs will run more than $173.00

 

Oopps I forgot about the EGR system..

Looks like your ECM threw the code for that now.

Test the EGR solenoid and check the vacuum line, it could be cracked or plugged with debris.

if you did not get an O2 sensor code why replace it ? when it goes bad the ECM will let you know..

Also make sure the PVC valve is working and that line vacuum line is clear..

 

Already replaced the PVC valve. Have to put parts purchases on hold for a couple weeks, but I'll recheck all the vacuum lines, and some other small stuff.

 

sounds like the EG system has an issue but after you service that

remove and inspect the spark plugs too:

if they are worn out replace them same with the cap, rotor, wires , air filter, etc.

A basic tune-up will go a long way and should be the first thing you do with a used car, especially if the PO has not touched it.