Failed smog miserably

[Craig 94 TA GT]

Since my last smog, I've added SLP headers, Carsound cat, new EGR valve, new plugs/wires, Dynaspark opti, new timing set, lower gears and PCMforless tune.

Well, prior to those mods, my NO(PPM) reading was ~300 for 15 mph, and ~260 for 25 mph. Max allowable is 689/706. Well I just had another smog test and my NO(PPM) is now 1008 and 855. The numbers about tripled. I'm not quite sure why since my EGR is supposed to be new. One thing I do have is an exhaust leak on the driver's side header, causing the BLMs to go around 145/120. I also had slight leak also with my old manifolds though (last smog check)....so I'm not sure that this can cause the NO to triple.

So my question is, what should I look for? Do I need to repair that exhaust leak, and/or do I have a PCMforless tune that's causing it to fail? I already questioned them to make sure they didn't delete my EGR system, but I'm a to hear a response. Is there a way I can test my EGR system, physcially or scan?

HC and CO are fine.

EDIT Here's the chart


Thanks for any advice.

[SteveH95Formula]

I've heard that your EGR will only work at or near full throttle which I doudt that is will be tested but I could be wrong. Usually aftermarket cats. flow good but usually fail. Its best to stick with stock cats if you need to pass emissions.

[Craig 94 TA GT]

I think it's the other way around - the EGR doesn't work at or near full throttle - it works only under partial throttle, which is why many say you don't gain any hp when you delete it. But I could be wrong

[Christopherrr]

The EGR only works at partial throttle...it's closed at WOT.

Hmmm, have you replaced or deleted your O2's by any chance?

[Craig 94 TA GT]

Yes, the O2s are new when I replaced the headers.

Something has caught my eye though - I'm reading that low CO and high NO may be from high combustion chamber temperatures (from possibly being lean). And the last time I had the PCMforless tune in there - when I got it dynoed - was when the dyno operator said my car is gonna blow up. It was running way too lean and literally melting his equipment. My plugs were super white too. Hmmm, I wonder if this has something to do with the problem??

[Injuneer]

High NOx, coupled with low HC and CO will generally indicate its running lean. Couple that with a low back pressure exhaust, causing low flow when the EGR valve opens, and it may be a combination of the two.

Unfortunately, the OBD-I diagnostic for EGR flow is not very sensitive - you can completely delete the EGR system, and 80% of the time it won't set the code. Might be worth checking the valve to make sure it responds to a vacuum. Make sure the solenoid opens when it gets a ground. Make sure the vacuum lines don't have any holes. Check the EGR valve pintle and the hole in the manifold for carbon buildup. Check the riser tube from #8 to the intake to make sure its not plugged.

NOx increases as combustion chamber temps increase, so hopefully its not running with the coolant on the high side.... worth checking the coolant temp at the conditions it was tested.

On your Carsound cat, is it the correct monolithic cat with NO connection for a line from the AIR pump?

[Craig 94 TA GT]

Thanks for the info Fred.

As far as the temperatures, it's running with the stock fan settings. I may have been mistaken by doing this, but I always thought, the hotter it runs, the less emissions. It has worked in the past, but that's when I was nearly stock. So coolant temps were in the 215-240 range for the stock settings. Should I have turned on the fan switch to keep it around ~160-180?

As far as the cat, I'm using the Carsound universal fit one, model 94109 (I think). It should be this http://cgi.ebay.com/ebaymotors/Carso...spagenameZWD1V

I had the Borla cutout completely closed, to make sure they don't fail me on noise pollution, as well.

EDIT: I just got a response from Bryan..."We may want to try less timing, the EGR is still active. Often with aggressive timing the NO emissions can go up."
Looks like I'm going to switch to stock configuration on the next test. I get 1 retest for free.

[HottestZ28]

Try running it cold, heat on full blast- cooling fans pointed to the nose. You have room for an increase in HC/CO running alittle rich will bring NOx down as well.

[Craig 94 TA GT]

I think the problem may be the tune - I read on cz28, someone with high NOx tried to smog it cold and ended up with the same NOx count. My case may be different, but I tried a few things:
- Pushed the EGR to make sure it's not stuck. It pushed fine, a little firm but seems normal.
- Checked all vacuum hoses and rerouted a few that were very close to the valve cover.
- Cleaned air filter (it was VERY dirty)
- Loaded stock tune.
- Going to add a bottle of emissions passing additive (or alcohol)

But another big difference between 2004 and now is the RPM


1300 vs 1700-1900....I guess the RPM for these gears isn't good at those MPH.

I'm going to try again tomorrow...hope it'll pass

[Craig 94 TA GT]

Well, I did a few more things before the latest smog...
- Cleaned MAF
- Seafoamed the car (1/2 bottle through the brake booster - LOTS of smoke), and 1/2 bottle in the gas tank.
- Drove 15 miles through freeway and city streets to make sure it was really warmed up and hot.

Well, I just barely passed! I'm definitely happy the T/A is legal for 2 more years, but am worried because all the other emissions went up.



Hydrocarbons more than doubled, NO decreased just enough to pass, and CO the same. I'm guessing this was mainly due to the stock richer tune

I know it's definitely time to fix my my exhaust leak at the head, but I'm planning on doing this with ported AI heads, and eventually other things for the motor. I'm really worried that if I can barely pass now, I will never pass with a H/C forged 355 setup in the future. Or pass with just one more mod.