Background:

Back in August I failed emissions and found out one of my injectors was bad. I replaced them all with cleaned ones a couple months later, and failed again. Typically I would fail on HC and CO both at idle and driving. NOx on the driving would be a narrow pass.

Since then I've put in a new O2 sensor, plugs, cleaned my K&N air filter, changed the oil, knocked the base timing from 6* to 2* advance.

This weekend:

The car has been sitting since that last emissions attempt so I filled it with 94 octane Mohawk gas and took it around town for a good long while before trying my luck at aircare. With the new tune-up stuff done, my car felt like it was running very well, and I was suprised how it pulled when giving it some pedal a couple times.

Anyways, I failed again on almost all categories and NOx too. The only category I (BARELY) passed was HC in the driving test. What a disappointment.


I don't really want to "cheat" to pass emissions as I want my car to operate properly. I'm wondering what you guys think I should look into... otherwise I'm guessing that both of my cats need to be replaced. I'm not sure how old they are, maybe they're the originals. My car has 182,000 kms on it.

Thanks for any advice.

 

a higher octane gas will not help you pass emissioins, matter of fact, it will lessen your chances of passin.

Try adding a additive (its not anyone would say your cheating by just trying to clean your injectors, right?)

do a search here, you'll find all kinds of stuff u can do with your set-up to help you pass.

 

Thanks for the reply hydric. My car normally takes premium (92 octane) and around here Mohawk 94 is known to be the "cleanest burning". Maybe changing my timing had more to do with the combustion.

My injectors should be very clean, thanks to Rich at Cruzin Performance.

I tried doing stuff like using isopropyl alchohol to hide the HC's, and raising the idle to pass the idle test easier. I would get better results on the tests but still fail. My car is very close to stock, and if it is running properly I assume it would pass everything easy and not even be close to the maximum limit.

 

High hc's and co's indicate a rich mixture with some misfiring. Is your ignition up to par? Egr plugged(high nox)? Id try pulling the egr and cleaning it and maybe make a small vacuum leak to get it running leaner(which will raise your nox so the egr better be working).

 

Head down to the hardware or paint store and buy a gallon jug of denatured alcohol. Dump that in the tank, I bet you'll pass. That's what I do!!

 

So there's nothing wrong with my car? Except that its from 1989? I'm just wondering if I need to cheat to pass. I hope I can get my car in tune so that I don't need to.

 

Aren't vacuum leaks bad? I just want to know if I should rule out anything else before I change the cats. I havent done the fuel filter in a couple years, but I haven't driven the car a whole lot.

 

Vacuum leaks are definatly bad. Its just a way to make your car run leaner.

 

You shouldn't need to cheat to pass. I've got 78's and 73's that pass, and my 87 IROC with 125K passes the 'high end' test with no problems. What you DO need to find, is your problem/s. And you could have numerous issues. Fouling plugs, bad wires, vacuum leaks, FPR not working right. If your cats were bad, it'd probably RUN really bad. Is the car throwing any codes? Do you hear any hissing noises with the car running and hood open? Ether works great for finding vacuum leaks, just do it in a WELL ventilated area! Or they'll find you nose down in the engine! Make sure your car is getting up to temp, hot cars burn more efficiently, therefore run cleaner. If the car has a performance chip and the 160 thermostat, it may cause you some problems. Is your emissions test static? Or on a Dyno? Dyno tests may cause some performance computer chips to have issues. I could go on and on, but these are some places to start.

 

If they are the original type cats they most certainly need to be replaced. New high flow units will do 2 things: 1 - cleaner emissions and 2 - better exhaust flow (factory style cats aren't exactly known for their high exhaust flow). If you're just barely passing, this will definitely get you to pass the test.

 

I was talking to my Dad and he said to hit the cats with a piece of 2x4 and listen for a rattle. I did that and they both sound hollow. Could they be gutted? I got no history on this car before I bought it and it's always been pretty throaty and a bit loud. I've heard other GTA's around town and they sound a lot more quiet. Hmmm.. :P

 

Gutted is a definite possiblity. They shouldnt sound hollow. One thing about the high flow cats is that they arent as effiecient as the stock cats. However with how close your are to passing(assuming gutted cats) high flow cats should work for you.