failed emissions this morning.

[EagleMark]

I'd have waited for the right plugs. Not sure about the EGR? Your 8476 is just as good as 7747 plus has an IAT.

Do you have an Air Pump?

[one92rs]

No air pump

[Fast355]

The last time my 1983 G20 had to pass emissions in DFW it was a TBI injected, vortec head 8.9:1 350 with long tubes and no cats. Running without EGR and tuned with the EBL. On the loaded emissions dyno it ran cleaner than a 2006 ULEV Honda Civic that had the then new CAN databus that would not communicate with the state machine and had to be run on the dyno.

Low Speed Test (15 mph)

HC.... Standard...332 ppm....Reading.....50 ppm
CO.....Standard....1.89%.....Reading.....0.10%
CO2....Reading 14.5%
02......Reading 0.0%
NOX...Standard...2490 ppm...Reading....72 ppm

High Speed Test (25 mph)

HC.... Standard...326 ppm....Reading.....42 ppm
CO.....Standard....2.62%.....Reading.....0.03%
CO2....Reading 14.5%
02......Reading 0.0%
NOX...Standard...2320 ppm...Reading....47 ppm

The secret.....Disconnected timing connector and massively retarded ignition timing although you could burn a .BIN that had the timing map level at 10*BTDC and accomplish the same thing. It makes the exhaust hotter and the cat function better, burning up the CO and HC and at the same time lessens the cylinder pressure and therefore NOx emissions. In all honesty it was not much dirtier running with timing advance. I just wanted to make sure it would pass easily though. When it was carbureted, I disconnected the vacuum advance hose every year prior to testing (timing was advanced nearly 10* over stock). Retarded timing + leaner air/fuel ratio = pass every time with ease. It was a little dirtier with a Q-Jet on it, but not much. One year I tried to get it tested with a box stock Edelbrock 1405 on it and it was a gross fail. The HCs were 2x the limit and C0 was through the roof. Even jetted to a 1406 it failed. I pulled the Q-Jet off the shelf, tossed it on and instant pass.

[one92rs]

Im hoping to be able to log it when i get home. Then i can post it
On here for yall to see what you can find. Actually hoping something sticks out like a sore thumb.

[EagleMark]

Maybe? That is what we want to rule out. But from what Fast is saying it's probably all the spark I have in your chip... or that and as Buzz mentioned a non efficient CAT. It's amazing how much a CAT can clean up and for the little bit of HP lost it's really just a good thing for the air!

[one92rs]

here is the log I did today. popo everywhere and 5 oclock traffic. got a good freeway run in there. and a couple small full throttles.

yeah but that chip runs very well. I like all that it does.

[Fast355]

Maybe? That is what we want to rule out. But from what Fast is saying it's probably all the spark I have in your chip... or that and as Buzz mentioned a non efficient CAT. It's amazing how much a CAT can clean up and for the little bit of HP lost it's really just a good thing for the air!

Are you using your 14.1:1 stoichiometric trick in that chip? Also have you tried lowering the 02 voltage cross points about 10%. Leaner will reduce the HC/CO but increase the NOx. Leaner than 14.7:1 can also reduce the NOx by reducing combustion temps but go too far and it will pickup random misfires that will increase HC. Retarding the timing will further cut the HC and at the same time lower the NOx. How old is the 02 sensor? If it is a non-heated sensor GM once recomended to replace them every 30K. A sensor that is starting to fail will run the engine richer and richer, causing emissions to increase.

Changing the oil seems to help as well. You could also block off the PCV vacuum hose internally as that will help lower HC.

FWIW the california .bins were always richer with the timing more retarded and almost always had an air pump. The richer mixture and retarded timing decreased NOx and the air oxidized the HC and CO.

[one92rs]

I got this chip from EAGLEMARK. that 02 sensor is less than 2 years old and is the casper electronics heated 02 sensor kit. no air pump on her either. was going to change the oil right before going back to inspection. I can block off the pcv valve. the inspector is really cool. he wouldn't even care if the pcv wasn't on there. is there a way to retard the timing manually?