Aftermarket header cause EGR not to function?

[modulation]

I've read a few post that says switching to after-market exhaust can lesses the backpressure so much that the EGR no longer works. Is this true?

I recently passed emissions in Georgia with a stock exhaust manifold and after-market 2.5" cat-back.

Fast forward 6 months. I live in California and failed emissions with the same car which now has a Ebay OBX header and same after-market 2.5" cat-back.

My NOx is sky-high "gross polluter" limits. My CO2, O2, HC and CO are all fine (infact pretty low, lower then they were GA.) It was semi-close to passing on the 15mph test but not even close on the 25

NoxMph - Max - Meas15 - 799 - 103225 - 738 - 1859

My timing is set to stock. My car runs great.

[r3v_v3ng3]

I've read a few post that says switching to after-market exhaust can lesses the backpressure so much that the EGR no longer works. Is this true?

yes its true

also is Georgia smog testing the same as California?

[modulation]

CA is of course way more strict.In GA if you pass the sniffer that is all they care about, no visual check, no CARB papers needed for mods etc.

But the actual ASM emissions test are pretty much the same there are just different max values.

For example:The max in Georgia for nox @ 15mph was 945ppm.The max in CA for nox @ 15mph was 799ppm.

So CA just has lower maximums. I got 1859ppm on the CA test so I would have been way too high for the GA one too.

I guess I'll be going to a junkyard to get a stock exhaust manifold and put it back on and try to pass.

[r3v_v3ng3]

this is the reason why i keep most or all my stock parts that i take off specially emission related. it just sucks cause i toss some away on the garbage and later try to buy it. well good luck on your smog.

[Cone Junky]

I just had similiar numbers with my CA smog. I have stock/midas crap exhaust, but the culprit was a small exhaust leak before the cat.

ANY exhuast leak before the catalyst will make your NOx levels skyrocket.Another common problem with these cars is the EGR ports. Might be worth the $5 intake gasket to remove the inspection plugs and check/clean the EGR ports.

[modulation]

I just had similiar numbers with my CA smog. I have stock/midas crap exhaust, but the culprit was a small exhaust leak before the cat.

ANY exhuast leak before the catalyst will make your NOx levels skyrocket.Another common problem with these cars is the EGR ports. Might be worth the $5 intake gasket to remove the inspection plugs and check/clean the EGR ports.

Thanks for the advice.I thought the emissions dude was going to let me slide with the header but he wanted $100.

Since I think it might be the aftermarket header causing the EGR to not work I might as well pick up a stock exhaust manifold at a junkyard and throw them on. It'll cost me ~$70 but at least I can take it anywhere.

When I throw the stock manifold on I'll double check all my gaskets and exhaust for leaks. If I still don't pass after that I'll be cleaning the EGR and crap. My GA tags don't expire for another couple of months so I've got time.

If I still can't get it fixed within 1 month then I'll resort to being hardcore..I've got a nistune and a wideband o2 (the wideband o2 isn't installed yet) and I'll tune the A/F ratio until I pass.. ;-)(I'm not 100% sure this is possible but pretty damn sure.)

[Cone Junky]

I also ran the factory colder range spark plugs and set the timing to the minimum (13 deg). High combustion chamber temps will also contribute to NOx, so every little bit helps.

[modulation]

I also ran the factory colder range spark plugs and set the timing to the minimum (13 deg). High combustion chamber temps will also contribute to NOx, so every little bit helps.

I would lower my timing alot but I can only get away with 2 degrees up or down.

They flagged me the first time I failed since I had advanced my timing by more then 2 degrees.

How'd you get away with it (really high timing) since you live in Cali?

[modulation]

I just had similiar numbers with my CA smog. I have stock/midas crap exhaust, but the culprit was a small exhaust leak before the cat.

ANY exhuast leak before the catalyst will make your NOx levels skyrocket.Another common problem with these cars is the EGR ports. Might be worth the $5 intake gasket to remove the inspection plugs and check/clean the EGR ports.

Dude IM/Message me your paypal address and I'll send you $2 so you can buy a cookie cause you deserve one.

I went back to a stock exhaust manifold and while I was changing it out I noticed some nice black marks on the gaskets that went all the way threw so it looks like I was leaking.

I put the stock manifold back on, new gaskets, and tightned everything really good.

I PASSED! Thanks the car gods..