can't pass emissions inspection (NOx)

[notsonic]

i have a 95 3.4l v6 camaro, auto. it has a magnaflow/carsound high flow cat, with a flowmaster american thunder catback. stock manifolds. its also got a cold air intake.

i went to inspection in early january. my NOx emissions were 1575, and it says the standard is 879. i went again today, my NOx emissions were 1428, standard 907. it passed the HC emissions both times by a large margin (35, with 117 standard.)

the first time i took it it was on 87 gas and no egr valve. today it was on 93 gas and i put the egr valve back on.

since ive put the egr valve on im noticing better fuel economy. but the valve itself leaks and makes a lot of noise.

do i need a new egr valve or is something else wrong? also im almost positive i've passed inspection before with this exhaust setup, but at that time my egr was on and working fine.

[cam98aro]

Re: can't pass emissions inspection (NOx)

your egr gasket may be leaking

[zpwn06]

Re: can't pass emissions inspection (NOx)

obivously your egr, thats what theyre designed to do, but here are some other things you can try: sometimes if you drive one the highway a long time you can heat up the cat alot though not sure if that'll help with NOx. You could probably also take off your cai, and tape your IAT sensor to your radiator. If all that doesn't work, put a sock over your tb and secure with a hoseclamp. To avoid NOx you want the fuel burning at as low a temperature as possible, so warm, dry, restricted air.

[bigbrian442]

Re: can't pass emissions inspection (NOx)

The EGR's sole purpose is to reduce NOx by lowering combustion temps. Better fuel mileage is a by product of it. Start with that. Make sure you take a long drive at highway speeds before your car is tested.