black95z0122

i live in mass and have to do the treadmill type test and just failed. It failed on the HC portion of the test. Any ideas why? I have all my emissions stuff still on the car and i have new 02 sensors and spark plugs.
Reading limit Pass/fail
HC grams per mile 1.99 1.2 fail
Co grams per mile 4.62 20.00 pass
NOx grams per mile 1.49 2.50 pass

Any ideas? What should i do? i have 60 days to fix.

faded93bird

How many miles are on the cat? If a few I would say get a new one, ebay a cat-co is like 40 bucks.

If new..... are your fans on too low the car needs to be nice and hot when you go threw.

faded

black95z0122

its the cat that came w/ the car and i have 72000. I was wondering if that might be it. this is the second time that i failed. i failed two days ago and i figured it was because i only drove it for 10min before but this time i drove for at least a half hr on the highway before.

i also wonder if its the station because i went to a different one this time. when these guys did it they back the car up these fairly steep ramps and did the test with the car at an angle like that. two years ago the place i did it at just had the rollers built into the floor.

If i end up replacing the cat should i go w/ a aftermarket one or do those ones put out a little worse emissions than the stock one for proformance?

thanks alot

Z06Z28

do you remember what your coolant temp was? and when did you put those spark plugs in (your sig)...in reference to you failing emissions.

black95z0122

i can't remember exactly but it was right where it goes when its all warmed up. around 185, 190 i'm guessing by the gauge it was a hair above the second line from the bottom

black95z0122

i changed the plugs after my before this test after the last one. their ngks gapped at 35

Z06Z28

So after the first time you failed, you have new 02's up front and new spark plugs. Your temp around 180-200 is fine. Might wanna double check your plug wires for any burns and make sure their snug on their good...also see what your A/F ratio reading is. Check for exhaust leaks. I noticied in your sig you have some kinda modification to your MAF and fuel press reg...try putting the stock MAF and screen back in if you swapped it out.

Evilfrog

Change the Cat. It is more than likely what the problem is.

The car isn't missing is it?

black95z0122

i don't have the old maf the previous owner changed it out. how to i find what my a/f readings are? Do i need and scanner tool?

sorry if i wasn't clear i put in new plugs and o2s before i failed for the first time and after i passed two years ago.

Also i my HC numbers went bad during the deceleration part of the test. the numbers up to there were fine

FULLSLP1

just went through this.... double check your fuel press. and clean out the mass air sensor....mine was a dirty MAF and IAT .
check anything that could make you run rich...air intake elbow torn ect. all the little stuff.....

black95z0122

ok so i changed the oil bc i heard that that could help, it was about time anyway. i also check the MAF and IAT. They were clean. i checked the plug wires they were all on the plugs all the way and they wires didn't look burnt. i'm gonna go again tomarrow and give it a shot. i also put 1 gallon of denatured alcohol in the tank and i'm gonna pull my fan relays before i start the car to go drive around and warm it up. I'm also going to a different shop this time to get it done. the same place where it passed two years ago. hope it works.

i also noticed somethig. the shop that failed me didn't have a big fan blowing on the car when it did the test and the shop that passed me before did. do u think my HC levels could have been a bit high because of the stagnant air in the shop?

black95z0122

failed again. tried 1 gallon of denatured alcohol in 3/4 tank of gas (93).HC counts were even higher this time

2.63 grams per mile limit was 1.2 grams per mile

BlownF1

I'd check/change the cat. That's a lot of miles, especially if you drive the car aggressively. As far as aftermarket cats, the GM one scrubs the best, but my car passed beautifully with a Carsound hi-flow cat, so they do a decent job.

black95z0122

i just called this local custom exaust shop and he told me that the cat really only helps NOx emissions????

Z06Z28

I'm trying to think why your HC levels are up there. Try this, you said you changed your 02's and you mostly likely dropped out the y-pipe. I would check to make sure that the flange bolts on both sides is nice and tight, you may have a leak but double check them. I would probably find someone off the board in your area that has a scanner for your car like... AutoXray I beleive is the name of one. Check out this thread if you need help with reading parameters since Injuneer explains a few things and has a link of understanding some sensors. If you decide to go that route, you can post your readings and guys on here will be able to guide you. I hope this helps.