Hey every one,
i am having some emmissions problems. I have gone three times and faided each time. Between the secon and third try i installed two new magnaflow highflow cats 2.5" because i was failing and also because they were stock as far a i knew and one was blown. on the third test i did wors than the second one with the old cats and one blown. I dont know what i should concider next. my key question is how important are the o2 sensors, thoes are the tubes that stick out of the cats right, because a while back i had a mechanic doing some work installing my cutouts and i dont remember why but he cut the ports off and welded them shut, should this be effecting me, and is there anything i can do. also the guy at the emmissions place said my problem was i there was too much un burned gas in my exhaust. can this be fixed by ajusting the air fule mixture and if so how can i do that. also will a stronger ignition system help mabe larger gaped plugs or an upgraded coil or ignition box. also i was concidering a adjustable fuel pressure regulator, if i got that would i be able to bring down the fuel pressure to solve my problem.

As you can probubly tell i am somewhat new to all of this emmisions stuff, only 17, and i also have a very small budget, but thanks for all of the help guys. i know the answers are out there so help me out, if you need any more info just post and i will reply asap.

Car specs:
1991 Camar z-28 Dual cat
-5.7 TPI (Speed Density)
-nkg plugs
-msd helicore wires
-magnaflow cat back
-flowmaster y pipe
-magnaflow cats 2.5" ( air pipe coming out)
-slp coated shorty headers with AIR
-flowtech cut outs (dual before cats)
-Stock air filter and intake system.. Wil after marcket intakes or filters help to clean up my emmisions?

Thanks again,
Eli Jacobosn
Raptere

 

considering your air/fuel ratio is computer controlled that shouldnt be an issue. Too much fuel can be a couple things. First of all im not sure where your 02 sensor is mine is in my headers but that is one of the key pieces your car uses to determine the air-fuel ratio. If yours was removed that could definitly cause it to run too rich. Also have you done a tune up, ie cap and rotor, new plugs, etc anything that has to do with spark because if youre not getting a complete burn then emissions go through the roof. Could possibly need a new EGR. Ummmm thats the majority of the emissions stuff right there.....oh yeah check for codes on your car. If youre not sure how im sure someone else will chime in i dont feel like remembering but theres a tech article me thinks on the thirdgen.org main page

 

EGR has nothing to do with a rich mixture.

Are you getting the car good and hot before you pull in to the testing station? The cats need to get good and warm to work properly. Same with the O2. It needs to be good and warmed up to operate properly. Usually the O2 is warm enough to work in short order, but if it is a little old and tired it might take longer to warm up - or it might just need to be replaced.

I don't know about those cats, but the factory ones need those fresh air pipes (AIR) to be operational to allow the converter to operate properly. I would put those back on ASAP. Either way it will pump outside air into the exhaust stream behind the O2 and make your emissions *seem* *better* to the emissions testers.

An AFPR can help a bit but if the O2 is tired and the converters aren't hot and have the AIR pipes going into them, it will take a lot of messing with to get it to pass just by lowering fuel pressure.

The bottom line is there is nothing inherent in your vehicle that would make it fail. Something (or thingS) is wrong.

 

where is the o2 sensor and could some one post a picture of this location.

and on the air tubes commign out of the cats how impotant really is that because i just put 100 dollars into these new cats because my my mecanick said emisions would be fine without them and if i were to get the ones with it theat would be even more money and also i think he removed the piping leading to them too so i woulod have to have the whole system redone right?

 

3rd gens have one O2 sensor, in the driver's side exhaust manifold. Sensor in the cat came in later years.

A properly operating O2 sensor can make a big difference. The "failure" mode is to go rich, which can happen w/o any SES light. The sensors have come down in price in recent years, and are a common "tune-up" item. 60k miles is about all you should expect out of one.

The tubes that were cut off the cats were, as mentioned, air injection tubes. They provide extra oxygen to help the cats do their job. Taking them off is silly if you need to pass sniffer (and is an automatic fail in many places with emissions visual inspection). You'd be best served to get them back on (you were given bad advice to remove them).

I'd try to O2 sensor first, though. Also check fuel pressure. Low pressure can actually make it burn dirtier (poor spray pattern).

 

no but on most e-tests they test for NOX and that will have a huge impact on that section of the test.

As far as your AIR tubes if you dont have to pass a visual dont waste your time. People have proven by removing them and doing an e-test that they are more a waste of hard wear then anything else. While they will help a tiny bit your car should pass easily without them.

Replace your O2 sensor it causes a rediculous amount of people to fail the sniffer. Other then that just do a full tune up. MAKE SURE YOUR AIR FILTERS ARE CLEAN. Engines dont burn fuel without air so if your car is choking to death because of clogged up filters your going to have a lot of unburnt fuel coming out the tail pipes. Even if theyre borderline replace the filters just because it will definitly help.

Also can you please post what you got and what youre allowed for each of the different gases they tested for. It will help us out a lot in terms of figuring out your problems.

 

Had he been asking about NOx it would be entirely different, true. But he isn't. High HCs has no correlation to NOxs and thus no relation to EGR. Just eliminating things to check.

I don't know who told you the AIR system does nothing, but they are wrong.

First, read this (it's a few pages, does a pretty good job):
http://auto.howstuffworks.com/catalytic-converter.htm

Thirdgens were still pretty new to the fuel injection game and have things like a non-heated O2 that create situations where the mixture is likely not ideal and thus the oxygen content of the exhaust is also not ideal. The addition of fresh air being pumped into the middle chamber of the cat to provide more oxygen is part and parcel of our control systems.

As I mentioned, if the aftermarket converters he bought have more effective materials in them and thus don't need the additonal oxygen, he likely does not need the pipes for them to operate. I would be very wary when using aftermarket converters that don't have any AIR input on them at all as they may be designed with a much more advanced fuel management system in mind that is running the engine and providing adequate oxygen in the exhaust to do its job.

However, with the AIR system opeational, it will be pumping fresh air into the exhaust stream regardless of all of that since the AIR pumps on our cars are mechanically driven with full flow diverted to the converters after initial startup - which can only make the HC level lower by volume. That would be like..... a good thing for him . But if I understood correctly, there are tube fittings sticking out of his converters in which case they can accept and will need that additional fresh air....

I do agree that it is quite possible that something else like a lazy/dead O2 or dying fuel pump is the culprit as, if the catalytic converter is nice and hot, it might still get him through the inspection if the tune in the PROM is in the ballpark even without the AIR system operational.

 

i am starting to get a gist of what is goign on, thanks a lot guys.

for the cats i am running two Magnaflow Carsound 2.5" the 4000 series i believe and they are concidered high flow about 16"long if that is important. for the emmisions numbers i am getting:

Hc- Standard .8/ Reading 1.17
Co- standard 15/ reading 14.2
Co2- standard na/ reading 380.9
nox- standard na/ reading na

Also i found my o2 sensor and it looks fine but mabe if they are cheep that would be a good thing to try to pass. also not seeming too cheep i hope you were saying bad air filters can cause bad combustion, what if i were to stop a block from the testing place and take the two filters out totally then put them right back in when i was done.

Also i am tacking an automotive service class through my highschool, very cool, and on of the other guys suggestes using octane buster, some kind of "make you pass emmesions aditive for the fuel, or just rubbing alchahol in the tank. What have you heard about these posibilites and if they are supposed to work what combination shoud i use of them and how much? also can they hurt the car?

Again thanks a lot for all of the help this is taking a lot of burden off of me,

Eli Jacobson
Raptere

 

he never really said what category he failed in so that info would be helpful.
EDIT: he was posting while i was writing this

Id still be willing to bet money that his O2 sensor is the main culprit.

And as far as the AIR i dont know enough cats quite honestly to comment (i dont feel like reading that article right now great site though ive learned a lot from it) but i have heard of a lot of people with third gens in good working order that have removed their system and gotten through the sniffer with ease.

MASSIVE EDIT:
o2 sensor ran me 45 bucks canadian but you need a special socket to take it out which they should have in your auto class.

You could completly take your air filters out but it puts your engine at more risk then id be willing to put it at even a tiny piece of dirt can mess things up real bad. If you need new air filters just get new air filters, paper ones are cheap, and K&N's filter better and will last the life of your car.

As far as you putting one of the "guaranteed to make you pass" emissions things you can buy at your local auto store its probably not a bad idea. Or you could take it to a mechanic and have them run an engine vac on it. Basically just think of it as fuel injector cleaner for your whole car it removes a large amount of the carbon that builds up inside your engine. Shouldnt cost you more then 40-50 bucks....heard of some people paying like 150 for the job but theyre getting ripped off.

 

on the topic of air filters how restrictive is the origional air intake set up i have the tpi dual filter set up would it be best for me to get two new ones of thoes or a cone filter to go strait onto the throttle body. also what have you heard about k&n vs Accel cool blue or even the sponge filters that accel makes they are supposed to be like there arent any filters even there resriction wise of course.and for the cone filter i know engine heat can hurt this but how much will it really and also i am concidering an ss hood with the cunctional scoop so that would supply much cooler air. Right?

 

Hi,

I've done a lot of research on emissions as of late:

1) Change your O2 sensor, its a good idea anyway. I do mine every 2 years
2) Change your plugs for a hotter plug. An Ac-delco 45RTS should provide a nice hot cyl temp and will aid the entire process.
3) Ensure your timing is stock. You don't want the ecm compensating for your advance, or worse, being retarded.

If this doesn't cure the problem, you have something else more serious somewhere. Perhaps a failed cat from backfire, etc. In closed loop the car should toggle 14.7 afr, which is passing with flying colors. As long as the cyl temps are high, and cats are working you shouldn't have a problem filtering the highs out.

-- Joe