odd smog test results

[Tom Cleary]

Hey folks, I need some help interpreting my test results. When I took my car in to get it checked the first time, I had the following smog test results:

Test rpm %co2 %o2 HCmax meas CO%max meas NOmax Meas
15mph 1687 12.1 0.0 130 190 0.81 4.20 1115 447
25mph 1751 14.4 0.0 105 95 0.61 0.61 945 152

So I failed slightly on HC and was a gross polluter on CO. I got a new catalytic converter, O2 sensor, and undid the AFM mod which had been set to 3 clicks. The only mods I have are homemade cold air intake, rabid chimp intake, thorley headers, 2.25 exhaust. Anyways, after the repairs, I have the following results:

Test rpm %co2 %o2 HCmax meas CO%max meas NOmax Meas
15mph 1705 15.1 0.1 130 45 0.81 0.02 1115 1327
25mph 1711 15.2 0.0 105 22 0.61 0.04 945 143

So what gives? Why am I failing on NO at only 15 mph and totally fine at 25mph? Is this a malfunction/clog in the EGR or should I be looking elsewhere?

Thanks much,
Tom

[pdupler]

Doesn't sound like its clogged since it works at one speed and not another. My guess is the vacuum modulator is screwed up. Follow instructions here:

http://www.celicasupra.com/phpBB2/viewtopic.php?t=3994&highlight=egr

If EGR is functioning properly, retard timing a few degrees, i.e. instead of 10 BTDC, try 5 degrees. That will reduce cylinder temps considerably and lower your Nox at all speeds and shouldn't adversly raise CO or H enough to fail. After you get it to pass, reset timing to stock or advanced as you prefer.

Phil D.

[Tom Cleary]

Ok, having looked at the egr vacuum modulator, it seem as though the connection on the side facing the front of the car is snapped clean off so I'm guessing I should just replace the whole unit. I don't think I can retard the timing to 5, but they might let me get away with 8 degrees. I believe the car is currently sitting at 12 degrees although I had some trouble when I went ot set it to 10 iirc. It looked as though the timing was jumping back and forth between 8 and 12 as far as I could tell.

Additionally, is it a problem if the speedometer no long works? IE, is there a speed sensor or something that goes into the ECU and might have an effect on my emissions? I was driving through the Salt Desert in Utah earlier this summer and I had the car on cruise control. Suddenly there was a loud sort of twang noise and the car jerked as the cruise control cut out and the speedometer stopped working. I don't think I've gained a mile on the odometer since then.

Tom