1993 240sx Almost Failed California Smog Today

[zer0c123]

Long post, so get a beer...

I just passed my smog check today, but after looking at the NO numbers, I almost failed. My car has been in storage since 2006, and has been started every few weeks. I did a minor tune up, but I doubt it would have affected the readings too much. I put about 2 gallons of denatured alcohol with about a ¼ tank of gasoline before the smog check. My HC and CO readings were not too far off when compared to the last 3 smog checks.

Back in 2005, I failed smog twice(TEST 1 and 2), because the EGR system was clogged with carbon. After the 2nd fail, I just left my car at a gold shield station for them to fix the problem. They cleaned out my EGR passages, retested my car and passed it (TEST 3). The problem was that car ran like crap and just didn’t feel right. The car would jerk when I put my foot back on the gas in lower gears. I took the car back to the shop and they said it’s probably EGR now, because it had been cleared of carbon and more air is flowing through. Therefore this would cause a difference in drivability. They a put a restrictor in the vacuum line going to the EGR and this helped a little; however, I noticed disconnecting the vacuum hose to the EGR fixed the drivability issue. The problem with take the vacuum hose off the EGR is that it killed my gas mileage. Eventually I decided to replace the parts to the EGR system.I replaced 1. EGR Valve2. EGR-BPT Valve3. BPT-Pipe4. EGR Pipe5. EGR valve and passage gasket

This solved the drivability issue. Now this is what annoys the hell out of me. I replaced all these parts to find that the NO level is still high. I tested the EGR bu pushing up and the car almost stalls. Also there is nothing wrong with the that small hose that connects the BPT and EGR valve. By looking at the readings, there doesn't seem to be anything wrong with my CAT. I do know that my exhaust system is getting pretty rusty, so mybe a leak before the CAT would cause this high NO level.


Modified by zer0c123 at 6:26 AM 3/25/2009


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