I recently moved back to northern CA from FL. Before when I was in CA the dyno smog test (simulated driving) didn't exist; testing was done while the wheels were stationary. Part of registering the vehicle was doing a smog test. My Connie failed the NO (nitrogen oxides) ppm emission test.
1/05/06 CA NO(ppm) emissions test results:
@15 mph 935ppm (437 max)
@25 mph 678ppm (724 max)
2/06/06 CA NO(ppm) emissions test results:
@ 15mph: 44
@ 25mph: 341
Right away the shop wanted to charge $99 to diagnose the problem. Not fix - only diagnose. I said I would come back later. The smog tech also asked if I had recently changed the battery because the OBD self tests also failed. I said the battery was disconnected before I left FL, but that was over 3000 miles ago.
I did some searches and found that the DPFE (Dynamic Pressure Feedback EGR) sensor was the likely culprit eventhough a CEL light wasn't present. The search also pointed out that the OBD self tests couldn't complete because all the IM (?interval monitor?) tests weren't done. It's possible for a DPFE to be so broken that it doesn't cause a CEL. So here's what I did:
* UIM/LIM rebuild
found 1 injector-to-LIM seal was cracked
cleaned carbon deposits from UIM, LIM, and throttle body
Replaced:
PCV valve, tb gasket, IAC & gasket, EGR gasket,DPFE, spark plugs and engine oil & filter
1)PCV - used clamps to insure PCV valve was secure
2)IAC - bought it long time ago but never put it on
3)plugs - used trusty APP764's
3)DPFE - pricey ($111, ouch)
Things I didn't change:
UIM & LIM gasket - replaced them 2 years ago, gave them a good soap and water bath
injector oil rings - replaced them 2 years ago.
