Failed Emmissions Again

[jmgtp]

Had it tested this morning, failed again. This test is with the addition of an EGR valve and some more tuning done.

From this morning:
HC (PPM) CO (%) NOx(PPM)
Limit 88 0.47 1029
Actual 153 1.22 825 (@ 2175 rpm)

So, I failed on HC and CO but passed NOx - this is the exact opposite of my last test where it passed HC and CO but failed NOx.

The results of my last test were:

HC (PPM) CO (%) NOx(PPM)
Limit 88 0.47 1029
Actual 28 0.01 1184

Not sure what else I can do. I feel like if we tune to lean it out some and bring down the HC and CO then the NOx is going to go through the roof. The catalytic converter on the car (for both of the above tests) is a less than 6 month old 3 way. The most I can think of doing is adding a second cat inline.

Open to suggestions. If I can't pass the e-test ultimately they will pull my registration and turn my car into a lawn ornament.

[talon2swords]

Had it tested this morning, failed again. This test is with the addition of an EGR valve and some more tuning done.

From this morning:
HC (PPM) CO (%) NOx(PPM)
Limit 88 0.47 1029
Actual 153 1.22 825 (@ 2175 rpm)

So, I failed on HC and CO but passed NOx - this is the exact opposite of my last test where it passed HC and CO but failed NOx.

The results of my last test were:

HC (PPM) CO (%) NOx(PPM)
Limit 88 0.47 1029
Actual 28 0.01 1184

Not sure what else I can do. I feel like if we tune to lean it out some and bring down the HC and CO then the NOx is going to go through the roof. The catalytic converter on the car (for both of the above tests) is a less than 6 month old 3 way. The most I can think of doing is adding a second cat inline.

Open to suggestions. If I can't pass the e-test ultimately they will pull my registration and turn my car into a lawn ornament.

http://www.nichols.nu/tip517.htm

The info. in the above link sounds pretty logical. You CC may already be shot. You need to see why some of your fuel mixture is going uncombusted.

[JustinParcher]

Not sure what engine/engine management this is running, but here's my experience. With other 60V6's, we're able to get almost identical results as your latest test. HC and CO are fine, but NOx is still too high. One thing I've found allows you to pass NOx is to retard the timing a bit for the test. On the older engines, no prob- just turn the distributor some and go back. Of course the majority of these engines don't have distributors, so it would require some tuning.

[Z26-T]

Random question.. When was the last time you changed your oil? I've done some emission tests on cars that failed, changed the oil, then it passed. Too many hcs in the oil. No promises though. I've had to use HEET fuel additive to pass those before. Typically lowers HC and CO, but will raise the NOx.

[Driver_10]

Excessive HC and CO are caused by incomplete combustion, whereas NOx is caused by excessively high combustion temperature.

Lean mixture, closed/clogged/inop EGR= NOx with no O2
Air intake leak after MAF, vacuum leak= NOx with high O2 and sometimes HC (lean misfire)
Lean misfire, clogged fuel injector= HC with excessively high O2 (usually with little or no CO)
Intermittent misfire, dirty air-filter, oil/ fuel fouled plugs, rich mixture, worn oil-control rings, dirty "fuel contaminated" oil, inop cat converter, low compression= high HC, O2 with no CO2 and high O2.

If youre getting excessive NOx, retarding timing or enriching part-throttle fuel enrichment may help. Water/ meth inj can do wonders for cylinder combustion temperatures too. For high HC's, cleaning /tuning up the engine does wonders. Check to see that you haven't fried you cat.

Thats all I can think of...

[60dgrzbelow0]

Hello Ol' Buddy... FWIW... Any chance of "pipe cleaner" cleaning out the entire length of the EGR tube...including getting up inside the manifold casting channel where the free-flow of the re-cycled gases might be blocked? That...and patient Seafoaming of the engine top-end via the vacuum line to the power-brake attachment might just do the trick here. I also concur on a fresh oil and oil filter change suggestion, too.

Mobil 1... 2 the rescue!

[TGP37]

Your catalytic may already be shot. Sometimes an underlying condition will ruin a new product quickly. So one should never rule something out just because it was replaced recently.

I agree with 60dgrzbelow0

It may be possible, bad injector spray pattern. Causing bad atomization of fuel resulting in more fuel needed to be sprayed and more unburnt fuel (liquid) getting dumped into the exhaust where it is furthered burned. The exhaust over heats and the catalytic starts to melt, causing a slight restriction.

I would dump half a can of seafoam into the tank, immediately fill the tank to full. Dump the other half into the crankcase oil. Drive until the fuel tank is near empty, change oil. Then replace fuel filter and oil filter. Seafoam the intake, replace spark plugs and air filter. Besure to confirm proper spark plug gap.

Fuel filters can get clogged and causes fuel pressure loss. Resulting in bad injector spray patterns. A simple test to check is put it in park and floor the accelerator. Let the RPM's bounce off the limiter a few times. If you have fuel press/flow problems, it will be apparent as the engine will bog down. If there is a restriction in the fuel and the RPM's don't bog down after bouncing off the limiter, then this likely isn't your issue.

Good luck