jgeorger

Subject says it all - today I passed the Mass IM240 emission after failing
badly 2 months ago. I owe many thanks to LJ in particular and the Internet
in general as they both said reducing timing reduces HC emissions, which is
what I failed on. Here are my old numbers:

HC 2.11 limit 0.80
CO 0.66 limit 15.00
NOX 0.71 limit 2.00

Today's numbers:
HC 0.72 (-66%)
CO 0.08 (-88%)
NOX 0.37 (-48%)

All units are GPM (grams per mile?)

What I did was halve the main spark table, 400 - 2400 rpm, 25-75 map. I
also halved the closed tps advance table up to 2400 rpm. Finally I raised
the fan turn on to 105 deg C (not quite as high as stock). I also drove the
car a bit before it went up on the rollers - and let it idle over 3 minutes
before the beginning of the test to make sure it was in closed loop. I
really can't remember from the initial test how long after they started the
car before the test started.

To be fair since the last test I replaced the stock TB with a BBK 52
modified for proper IAC operation (drilling the bypass hole in this case).
I also put in the ram-air maf tables after inadvertently running "regular"
f-body tables since my obd-1 conversion. However, while the maf would lean
the car out at wot, the computer should have learned around it by now, so I
don't think it would have affected the test.

I drove to work today on my regular tune - long commute - and I flashed the
emissions program in the parking lot. After the test I flashed it back.

So, as long as I leave the plates on the car, I won't have to take emissions
again til Aug 04. Hopefully by then the obd-2 **** will be figured out.

So, I'm pretty happy with the car. Now I gotta do something about that
damned coolant leak/smell.

Joe

quicksilver97ta

Cool, so basically you retarded the timing and raised the operating temp? Thats a big drop in your emmisions. I guess they looked the other way since you changed the loaction of the drivers side cat?? Also, they didn't plug into your OBD2 terminal under the dash?? PCMforless told me OBD1 conversions wont pass the plug in. Man they got issues here in Dallas, last week I saw a 'monitoring station' a van with a sniffer and a camera set up on an entrance ramp to I-20. WTF?? Saw it again later on the news. I want a cam and a revolving licence plate.

jgeorger

I did fail the obd plug-in test, but here the treadmill is a backup to it. They *may* make the obd pass mandatory, but then again they may not. Shrug.

These guys really don't care what you did to the car, they just do what the computer tells them to do. I saw that last time I was there. So I even told 'em I had long tube headers and that the car dynoed 375 rw. I swear to god if you could pass the obd test you could pull in with a car with gutted cats and a huge cam, spewing emissions, and as long as the RMV computer told them you passed, then they would pass you. They are removing almost any thought from the process here, that is what I am seeing.